Few things to know about Computers

419 Scam
A type of advance fee fraud originating from West Africa, so called because 419 is the section of the Nigerian legal code that covers the crime.

802.11
A standard for wireless networks that ensures interoperability between different manufacturers. 802.11 networks come in three different variants: a, b and g. 802.11b is the most common while a and g are much faster. Usually cards capable of faster speeds are backwardly-compatible to the b standard.

Access point
A wireless hub that links together different 802.11 network cards to form an ‘infrastructure’ wireless network (as opposed to ad-hoc).

Access privileges
The ability of users to read, change or delete files

ActiveX
A Microsoft system that allows reusable software components, especially applied to those downloaded on web pages to make them interactive.

Ad-hoc network
A wireless network that links computers on a peer-to-peer basis rather than routing traffic through a central access point.

Administrator
A user with sufficient access rights to allow them to manage the access rights of other users and carry out other high-level computer management tasks.

Advance fee fraud
Any fraud that tricks victims into paying money up front on the false hope of receiving a large windfall later

Adware
A form of spyware that displays unwanted adverts on a computer

AIM
AOL Instant Messaging, a system for doing instant messaging
Antivirus software
Software specifically designed for the detection and prevention of known viruses.

ASCII
American Standard Code for Information Interchange, a widely used code for digitally representing letters, numbers and punctuation marks

Attachment

Files, such as programs or documents, that are attached to an email
Authentication
The process for verifying that someone or something is who or what it claims to be. In private and public computer networks (including the Internet), authentication is generally done with passwords.


Back door

A loophole in a computer's security systems that allows a hacker access to it
Backup
Copying data and system files in case of disaster
Biometric
Using body measurements, such as fingerprints, irises, as a means of authentication.
BIOS Password
A BIOS is software code that links the operating system to the hardware – it is the most basic piece of software on a computer. It usually includes the ability to stop an unauthorised user starting the machine.
Black hat
A hacker who uses their skills to break into computer systems.
Bluetooth
An industry standard for short-range wireless connections between devices like mobile phones, headsets, computers and PDAs
Boot
To start up or reset a computer
Boot password
A password that applies while a computer starts up and before any operating system can be loaded
Botnet
A collection of PCs which have been infected by a virus and which are under the central control of criminals or evil hackers.
Broadband
Broadband connections to the Internet differ from dial-up connections in two ways. First, they are much faster, typically ten times quicker than a modem. Second, they are normally left connected to the Internet permanently and not just when they are in use. Examples of broadband connections include: ADSL, cable modem and fibre-optic leased lines.
Browser
A program that lets users read and navigate pages on the World Wide Web, such as Mozilla Firefox or Microsoft Internet Explorer
Buffer
A region of memory reserved for use as an intermediate repository in which data is temporarily held before it is transferred between two locations or devices.
Buffer overrun
A condition that results from adding more information to a buffer than it was designed to hold. An attacker may exploit this vulnerability to take over a system.
Bug
A failure, error or flaw in a computer program
Byte
A unit or measure of computer memory, usually consisting of eight binary digits (bits) processed together; usually enough to store a single letter or digit.

Certificate
An encrypted file containing user or server identification information, which is used to verify identity and to help establish a security-enhanced link.
Chat rooms
An online discussion group where you can chat (by typing) with other users in real time
Compact Disc
A CD-ROM is a data version of a music CD capable of storing up to 700mb of data. Using a CD recorder it is possible to create new CD-ROMs.
Computer security
The discipline, techniques, and tools designed to help protect the confidentiality, integrity, and availability of data and systems.
Cookie
A small data file that is stored on a user's local computer for record-keeping purposes and which contains information about the user that is pertinent to a Web site, such as user preferences.
Cracker
A malicious hacker who uses their skills to do bad things.
Cracking
Finding a password by trying many combinations and words.
Critical update
A broadly released fix for a specific problem addressing a critical bug.
Cyberslacking
Wasting time, usually at work, using the internet

Data Protection Act
The Data Protection Act 1984 sets out the legal basis for handling and protecting private information and data in the UK
Decryption
The process of converting encrypted data back into its original form.
Denial of service
Flooding a network with unwanted packets to slow it down.
Denial of Service Attack
By overloading a service hackers seek to make it unavailable to legitimate users. For example, by sending millions of spam emails simultaneously to a mail server, ordinary traffic will get clogged up.
Desktop firewall
A firewall that operates on a user's computer (as opposed to a gateway firewall)
Dialler
A piece of software that uses a modem to connect to the internet
Dial-up Connection
A dial-up connection uses a modem (or sometimes an ISDN terminal adaptor) to connect to an ISP. Usually these connections are quite slow and only open while the user is actually online.
Digital Audio Tape
A tape format used to store and backup data.
Digital signature
Data that is bundled with a message or transmitted separately and is used to identify and authenticate the sender and message data. A valid digital signature also confirms that the message has not been tampered with.
Discoverable
A Bluetooth device that has been set up to broadcast its existence to other Bluetooth devices
Domain Name Server
A server that converts recognisable domain names (e.g. Microsoft.com) into their unique IP address (e.g. 207.46.245.222).
Download
To transfer a copy of a file from a remote computer to a requesting computer by means of a modem or network.
Dumpster diving
A method of social engineering in which criminals raid rubbish bins to gather telling personal information
DVD writer
A device for creating DVDs
DVD-ROM
A version of the DVD format designed to store data rather than video

Easter Egg
An unexpected ‘feature’ built into a computer program by the author
Eavesdropping
listening to the information as it is transmitted over the air
Elevation of privilege
When a user (particularly a malicious user) gains more access rights than they normally have.
Email attachment
See 'attachments'
Email filter
Software that scans incoming email for spam or other unwanted material and filters it accordingly
Encryption
The process of converting data into cipher text to prevent it from being understood by an unauthorized party.
Escrow
When money or other assets are held by a trusted third party pending completion of a transaction

FAQ
Frequently Asked Questions
File sharing
Making files available over the internet to other users, typically music or video files
Filter
A program designed to monitor what is being loaded into a web browser or email program and block certain types of material
Fingerprint recognition
A biometric form of authentication using fingerprints
Firewall
Hardware or software designed to prevent unauthorized access to a computer or network over the internet
Flame
An irate email
Freeloading
where a wireless network is used to share a broadband internet connection, there is a risk that unauthorised users will bogart your connection
FTP
File Transfer Protocol, a method of transmiting data files over the internet
Full backup
A backup where all the chosen files are backed up, regardless of whether they have changed since the last backup
Gateway firewall
A firewall that operates at the point where a private local area network connects to the public internet
Geek
Someone who is fascinated by technology, perhaps obsessively
Gigabyte
1024 megabytes
Grooming
The process by which a paedophile prepares a child for a meeting, especially via the internet, with the intention of committing a sexual offence.


Hacker
Hackers are technical wizards. Most are innocent geeks who enjoy working with computers. However, some use their skills for more sinister purposes: illegally breaking into systems or writing viruses and other malware.
Hard disk
A fixed magnetic disk drive used to store data on personal computers
Hardware firewall
A firewall that operates as a standalone device, such as a router, rather than running in software on a computer
Hoax email
An otherwise harmless email that is designed to cause alarm or get itself forward to other users (or both). For example a fake virus warning or a chain letter.
Honey pot
A system designed to look like a regular network but which, in fact, monitors and traces unauthorised access.
HTML Format Email
An email that uses HTML to make emails look like web pages.
Hypertext Mark up Language
The computer code that is used to describe the contents of web pages.

ICQ
See 'instant messaging'
Identity theft
The crime of impersonating someone, using their private information, for financial gain
IETF
Internet Engineering Task Force is the body that defines the standards underlying the internet
IMEI
International Mobile Equipment Identification: a unique serial number built into GSM mobile phones. *#06# on your phone to find out its IMEI number.
Incremental backup
A backup where only files that have changed since the last backup are stored, making it quicker than a full backup.
Information Commissioner
In the UK, the Information Commissioner is the champion of public openness and personal privacy, in the context of the Data Protection Act 1998 and the Freedom of Information Act 2000
Information security
The art and science of protecting computers and data from misuse
Information theft
Theft of valuable data, such as customer records or engineering designs
Instant messaging
Sending short text messages in real time over the internet. Systems include MSN Messenger, ICQ, AOL Instant Messanger and Yahoo!
Internet Service Provider
A company that provides access to the Internet.
IP Address
A unique address that is used to identify a computer on the Internet. In its basic form it is made up of four numbers separated by dots, called a dotted IP address (for example 192.168.0.1).
IPSec
IP Security: IPSec provides security for transmission of sensitive information over unprotected networks such as the Internet. IPSec acts at the network layer, protecting and authenticating IP packets between participating IPSec devices.
IT security
See 'information security'


Java
A programming language originally developed by Sun Microsystems; now widely used on the internet and on mobile devices
Javascript
A programming language derived from Java that is used to make web pages more interactive

KB article
A technical document in the Microsoft® Knowledge Base accessible through Microsoft.com.
Key logger
A virus that logs a user's keystrokes as they type in order to capture private information, passwords or credit card information. Occasionally, key loggers can be physical devices attached to a PC.
Kilobyte
1024 bytes
Kludge
See Kluge
Kluge
an effective but inelegant solution to a problem

Layer-2 Tunnelling Protocol
Layer-2 Tunnelling Protocol: L2TP provides security for transmission of sensitive information over unprotected networks such as the Internet.
Linux
An open-source, freely-available operating system originally developed by Linus Torvalds
Local Area Network
A local computer network for communication between computers.

MAC Filtering
Each network card has a unique ID called a MAC. A wireless network access point can be configured to give access to specific network cards (and the computers in which they are installed) and exclude others on the basis of these MAC addresses.
Macro
A macro is a script of basic activities created by a user to automate repetitive tasks
Macro virus
A macro virus uses the macro capabilities of common applications like word processors to implement virus-like behaviour
Mail bomb
An excessively large amount of e-mail data sent to a user's e-mail address in an attempt to make the user's e-mail program crash or to prevent the user from receiving further legitimate messages.
Mail relaying
A practice in which an attacker sends e-mail messages from another system's e-mail server in order to use its resources and/or make it appear that the messages originated from the other system.
Malicious user
A person who has access to a system and poses a security threat to it. An example is someone who tries to elevate their privileges to gain access to data they are not supposed to see.
Megabyte
1024 kilobytes
Memory stick
A removable solid-state memory device
Microsoft Base Line Security Analyser
A free tool from Microsoft that searches computers for known security vulnerabilities and suggests remedies.
Modem
A device that links computers over the public telephone network, typically to connect to the internet
MP3
MPEG-1 Audio Layer-3 is a standard for compressing and storing sound files, typically for music
MP3 Player
A device that plays MP3 music files
MSN Messenger
See 'instant messaging'

Network
A number of computers that are connected to one another
Non-repudiation
A method of transmitting information (typically email) where the sender gets proof of delivery and the recipient is certain of the identity of the sender so that neither can later deny having processed the information

Online backup
A backup method in which data is transmitted over the internet to a trusted third party for storage
Open source
Computer software that has been developed in a collaborative way by volunteers on a non-commercial basis
Own3d
See 'Owned'
Owned
When a computer has been taken over by bad hackers


Packet
The basic unit of data transmission on a network
Padlock
A symbol in a web browser that indicates that an encrypted (SSL) connection is being used to communicate with a site that has a valid certificate
Pairing
When two Bluetooth devices establish a permanent, secure, trusted relationship
Patch
A software update.
PDA
A portable digital assistant, typically a handheld computer like a PocketPC.
peer-to-peer
A network in which each computer is capable of being both a server and a client; typically used to share music files over the internet
penetration testing
When trusted hackers simulate an attack on a computer system in the hope of revealing vulnerabilities and finding opportunities for improving its security
Pharming
An exploit in which criminals disrupt the normal functioning of DNS software which translates internet domain names into addresses. The user enters a correct address but is redirected to a fake website.
Phishing
An attempt at identity theft in which criminals lead users to a counterfeit website in the hope that they will disclose private information such as user names or passwords
Ping
A simple program that communicates with another computer over a network to see if it is responsive. Now often used as a form of human communication (“I’ll ping you later”).
Piracy
Illegal use or duplication of material covered by intellectual propery laws, such as copyright
Pop-up
A small window which appears over a web page to display an advertisement
Port
Each network service on a given computer has its own port, like a telephone extension.
Port scanner
Software which scans a given IP address looking for open ports
Port sniffer
A hacker program designed to find open or unguarded ports.
PPTP
Point-to-Point Tunnelling Protocol: PPTP provides security for transmission of sensitive information over unprotected networks such as the Internet.
Premium rate
A telephone number, prefixed by 00 or 09, which costs a lot when dialled
Private key
One of two keys in public key encryption. The user keeps the private key secret and uses it to encrypt digital signatures and to decrypt received messages.
Privilege escalation
See Elevation of Privilege
Proxy server
A firewall component that manages Internet traffic to and from a local area network (LAN) and can provide other functions, such as document caching and access control.
Public key
One of two keys in public key encryption. The user releases this key to the public and anyone can use it to encrypt messages to be sent to the user and decrypt the user's digital signature. Compare private key.
Public key encryption
An asymmetric encryption scheme that uses a pair of keys for encryption: the public key encrypts data, and a corresponding secret key decrypts it. For digital signatures, the process is reversed: the sender uses the secret key to create a unique electronic number that can be read by anyone possessing the corresponding public key, which verifies that the message is truly from the sender. See also private key, public key.
Public key infrastructure
Generally, the laws, policies, standards, and software that regulate or manipulate certificates and public and private keys.


RAID
A Redundant Array of Inexpensive Disks. Instead of using one large, expensive disk, most servers use a RAID array. There are different levels of redundancy, so a RAID level 5 has the highest level of safety. A single disk in the array can fail or even be removed and the data remains safe.
Recordable DVD
A DVD that is capable of storing data when used in a DVD burner
Remote desktop
A system that allows one computer to display the screen of another and to operate it remotely
Removable media
Storage devices that use removable media, such as ZIP drives
Repudiation
For example, buying something from an online auction and then failing to pay for it. Deleting or modifying a file in an untraceable or deniable way.
Rogue dialler
A dialler that is created by criminals to dial premium rate numbers
Root
An administrative user account with special privileges
Root access
Gaining access to a computer as a root user
Root kit
A set of tools used by hackers to get control of a computer
Router
A device that determines the next network point to which a data packet should be forwarded on its way toward its destination. Routers are used to move packets around the Internet and most broadband connections end with a router in your building that connects your LAN to the rest of the Internet.


Script kiddies
Inexperienced hackers who use publicly available tools.
Server
A computer that provides a service to other computers over a network.
Signature
The 'fingerprint' that is used by anti-virus software to detect an infection.
Smart card
A form of user authentication that relies on a credit card-sized card with an embedded chip
Social engineering
Tricks performed by malicious users offline to gain access to secure systems, for example impersonating a technical support agent.
Software firewall
A firewall that runs on a computer as a program, as opposed to a hardware firewall
Spam
Unsolicited commercial e-mail. Also known as junk e-mail.
Spoof
To make a transmission appear to come from a user other than the user who performed the action.
Spoofing
For example forging email messages or scanning internet packets to acquire a valid password, with which to hack into a computer.
Spyware
Unwanted software that secretly monitors a user's activity, scans for private information or gives outsiders control of a computer
SSID
The SSID is the name given to a wireless network which enables users to find it.
SSL
Secure Socket Layer, a public key encryption system that secures world wide web communications over the internet
Strong password
A password that provides an effective defence against unauthorized access to a resource. See Use strong passwords.

Tampering
Altering the contents of packets as they travel over the internet or altering data on computer disks once a network has been penetrated.
TCP/IP
Transmission Control Protocol / Internet Protocol. The protocols, or conventions, that computers use to communicate over the Internet
Technology journalist
A harmless drudge.
Token
A physical object, such as a smart card, used to authenticate users
Toolbar
An add-in for a web browser that adds functionality
Traffic
The transmission of packets over a network, signifying communication between computers
Trojan horse
A computer program that appears to be useful but that actually does damage.

Upgrade
See 'patch'
USB
Universal Serial Bus: a standard for connecting computers and peripherals
Usenet
An internet-based public bulletin board system that allows users to post messages to different newsgroups
User account
A set of rules defining access to files and systems on a computer that is personal to a given individual
Username
A code name that, with a password, unlocks a user account

Virtual private network
A private data network that makes use of a public network, such as the Internet, by encrypting data at one node and using security procedures that provides a "tunnel" through which the data can pass to another node.
Virus
Code written with the express intention of replicating itself. A virus attempts to spread from computer to computer by infecting another file, typically an executable program. Besides spreading, viruses can be used to do harm or for criminal activity. See also: trojan, worm and spyware.
Voice over IP
A technology for transmitting phone-like voice conversations over the internet
Vulnerability
Any product flaw, administrative process or act, or physical exposure that makes a computer susceptible to attack by a malicious user.

War chalking
Using chalk symbols on walls to indicate the presence and configuration of an insecure wireless network.
War driving
Locating insecure wireless networks by scanning for them with a portable computer and special software.
Warez
Pirated software
Webcam
A digital camera that can transmit images over the internet to users who access a given webpage
Webmail
An email system that uses a web browser to read and send emails rather than a standalone email client program
WEP
WEP data encryption is defined by the 802.11 standard to prevent eavesdropping and access to the network by malicious users.
White hat
A non-criminal hacker, who uses their skills legally
Wi-Fi
See '802.11'
Wiki
A collaborative method of developing content for a website
Windows Messenger
See 'instant messaging'
Wireless network
See 802.11
Wizard
A hacker of great ability. Also a high level administrator on a multi-user adventure game.
Worm
A subclass of virus. A worm generally spreads without user action and distributes complete copies (possibly modified) of itself across networks. A worm can consume memory or network bandwidth, thus causing a computer to stop responding.
WPA
WiFi Protected Access: a method of encrypting 802.11 traffic as a protection against eavesdropping

XYZZY
The magic word in Adventure, a game from 1977; often used in other programs.

ZIP disk
A storage device with removable media from Iomega

Video

PAL

Video:
Up to 9.8 Mbps* (9800 kbps*) MPEG2 video
Up to 1.856 Mbps (1856 kbps) MPEG1 video
720 x 576 pixels MPEG2 (Called Full-D1)
704 x 576 pixels MPEG2
352 x 576 pixels MPEG2 (Called Half-D1, same as the CVD Standard)
352 x 288 pixels MPEG2
352 x 288 pixels MPEG1 (Same as the VCD Standard)
25 fps*
16:9 Anamorphic (only supported by 720x576)

Audio:
48000 Hz
32 - 1536 kbps
Up to 8 audio tracks containing Dolby Digital, DTS, PCM(uncompressed audio),
MPEG-1 Layer2. One audio track must have MPEG-1, DD or PCM Audio.

Extras:
Motion menus, still pictures, up to 32 selectable subtitles, seamless branching for multiple storylines, 9 camera angles. And also additional DVD-ROM / data files that only can be read by computer DVD drives.

Total:
Total bitrate including video, audio and subs can be max 10.08 Mbps (10080 kbps)

* Mbps = million bits per second* kbps = thousand bits per second * fps = frames per second

Marpol Annex VI NOx

1. General Aspects
1.1 What are oxides of nitrogen (NOx)?
99% of engine intake air is comprised of nitrogen
(N2) and oxygen (O2). The nitrogen remains
largely unreacted in the diesel engine combustion
process, however a small percentage is oxidised to
form exhaust gases containing various oxides of
nitrogen, predominantly nitric oxide (NO) with
smaller amounts of nitrogen dioxide (NO2) and
minor concentrations of nitrous oxide (N2O). The
term oxides of nitrogen, or nitrogen oxides (NOx)
is used to group both the NO and NO2
components.
1.2 Are oxides of nitrogen (NOx) harmful?
Nitric oxide (NO) is relatively inert and only
moderately toxic but is readily oxidised to form the
more harmful gas nitrogen dioxide (NO2). As an
emission species oxides of nitrogen (NOx) are of
concern for several reasons. They are responsible
for acid deposition, respiratory illness in humans
and in association with sunlight and organic
material, the formation of photochemical oxidants,
namely ozone (O3) and smog.
Ozone in itself has detrimental effects on human
health, vegetation and crop yields, and contributes
in the degradation of certain materials. Ozone is
also a greenhouse gas, controlling the amount of
the sun’s UVB radiation from reaching the earth’s
surface and so contributes to the problem of global
warming.
1.3 How are NOx formed?
NOx are formed during the combustion process
within the burning fuel sprays. At these elevated
flame or combustion temperatures nitrogen is no
longer inactive and reacts with oxygen to form
nitric oxide (NO) and nitrogen dioxide (NO2). The
immediate reaction is the formation of NO. Later in
the process, during expansion and in the exhaust
system, part of the NO will convert to form NO2.
NOx is controlled by local conditions in the spray,
with temperature and oxygen concentrations being
the dominant influences. The higher the
temperature and the longer the residence time at
high temperature, the more NOx will be created.
1.4 When are NOx formed?
The stoichiometric quantity of air is defined as that
quantity of air containing the minimum theoretical
amount of oxygen required to fully convert all the
fuel into completely oxidised products, i.e. for
complete combustion. The ratio of the actual
fuel/air ratio to the stoichiometric fuel/air ratio is
an informative parameter for defining the
composition of a fuel mixture. This ratio is termed
the fuel/air equivalence ratio, φ, and is thus
defined:
( )
( ) φ =
F
A
F
A
actual
stoich
The critical equivalence ratio of the local mixture of
fuel and air for NOx formation is close to 1, i.e.
maximum NOx creation occurs when the local
air/fuel ratio is close to stoichiometric.
The critical time period for NOx creation is when
burned gas temperatures are at a maximum i.e.
between the start of combustion and shortly after
peak pressure. It has been shown that almost all
NO formation occurs within 20° of crank rotation
following start of combustion.
After the time of peak pressure, burned gas
temperatures decrease as the cylinder gases
expand.
The decreasing temperature due to expansion and
due to mixing of high temperature gases with
cooler burned gas freezes the NO chemistry.
NO forms both in the propagated flame front and
in the post flame gases. In engines, however,
combustion occurs at high pressure so the flame
reaction zone is extremely thin ( in the order of
0.1mm) and residence time within this zone is
short.
Thus, NO formation in the post-flame gases almost
always dominates any flame-front produced NO
which effectively de-couples the combustion and
NO formation processes. However, the reactions
which produce NOx take place in an environment
created by the combustion reactions, so the two
processes are still intimately linked.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
2. Control of NOx Emissions
2.1 What engine features control NOx
formation rates?
It has already been shown that NOx formation
rates are primarily a function of combustion
temperature (and pressure) and residence time of
the combustion gases at these high temperatures.
Hence any features of an engine which may
influence these variables will also influence the
emission rate. A list of the most influential of these
features can be summarised as follows:
• Injection and atomisation equipment
• Injection timing equipment
• Compression ratio
• Combustion chamber geometry
• Turbocharger type and build
• Charge air cooler/pre-heater
• Valve timing
• Rated engine speed
• Fuel composition
Fuel injection equipment design, timing and
pressure together with combustion space geometry
and fuel properties all influence the fuel
atomisation, spray patterns and penetration. These
factors are critical to the efficient mixing of the fuel
and air charge, significantly influencing
combustion efficiency. The quality of mixing of the
fuel and air in turn influences the local mixture
equivalence ratio, having a critical value close to 1
for high NOx emissions.
Advancing fuel timing and increasing compression
ratios tend to increase combustion pressures and
temperatures and so increase NOx formation rates.
Ambient conditions, as modified by the charge air
system, also influence NOx production. Increased
intake air humidity reduces peak combustion
temperatures and hence suppresses the formation
of NO in the combustion process.
Lower rated engine speeds increase the time over
which combustion takes place, increasing residence
time of the combustion gases at high temperatures
and so tending to increase NOx formation rates.
2.2 What effect does the presence of
organic nitrogen (N2) in heavy fuel oil
have on NOx emissions?
Nitrogen present in residual fuel is also a factor
affecting nitric oxide (NO) formation via a
different mechanism. Fuel derived NO proceeds
via a series of reactions, a key stage of which is the
formation of a NH compound which may either
progress to form N2 or NO. The nature of the
compounds in which the nitrogen exists in the fuel
is considered to be a factor in deciding the outcome
of the reaction but under certain conditions could
result in a 100% NO yield (amount of fuel nitrogen
converted to NO).
The NO yield is also sensitive to the fuel /air
equivalence ratio. Relatively high NO yields are
obtained for stoichiometric mixtures and are only
weakly dependent on temperature, in contrast to
the strong temperature dependence of NO formed
from atmospheric nitrogen.
In summary, increased nitrogen content in residual
fuels will increase NOx emissions.
2.3 What are Primary NOx Emission
reduction methods? Why not design
extremely low NOx emission engines?
The modified engine design approach can be
thought of as a primary method of controlling NOx
formation rates. As discussed, lowering the peak
combustion temperature is a very effective means
of reducing the amount of NOx formed.
Unfortunately, the amounts of other pollutants,
namely Particulates and Hydrocarbons, will
increase instead and there is also a substantial fuel
penalty as efficiency drops due to poor
combustion. The control of NOx emissions by
design is therefore an optimisation process,
balancing satisfactory combustion efficiency with
acceptable levels of all pollutants.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
2.4 What Primary methods can be
adopted to reduce NOx emissions?
Manufacturers have explored many different
methods of reducing NOx by primary control
methods. Some of the more publicised are listed as
follows:
• Delaying fuel injection. Retarded fuel injection
timing retards the combustion process. Nitric
oxide (NO) formation occurs later and with
lower concentrations.
• Reducing the amount of scavenge air, hence
reducing the quantity of excess O2 available for
conversion to NOx.
• Common Rail control - Common Rail fuel
injection has proven to be a very effective way
in combating smoke problems as well as a NOx
reduction technique. There are two main
ingredients, one being the freedom to choose
injection pressure and timing totally
independently of engine load, the other adding
an element of computerised control making it
possible to consider several engine parameters
and then automatically optimise the injection
and therefore combustion in each load situation
• Injecting water into the combustion chamber
(Direct Water Injection, DWI) Greater heat
capacity is utilised to reduce high peak
temperatures as the water evaporates
immediately upon injection. Rapid evaporation
of the injected water also helps to create a
homogeneous fuel-air mixture.
• Emulsified Fuel or Fuel-Water Emulsions
(FEW) is favoured by some manufacturers
claiming clear reduction in NOx emissions at
low cost with no significant design changes and
with no adverse effect on the reliability of the
engine. Other manufacturers claim that fuelwater
emulsions in a conventional injection
system causes considerable problems.
• Injection of very fine water mist after the
turbocharger using special nozzles
(Combustion Air Saturation System, CASS).
The fine water droplets evaporate fast and
further heat is introduced in the air cooler (now
acting as an air heater) and humidifies the
combustion air.
• Re-circulating part of the exhaust gas (EGR) -
this is one method of adding dilutants to the
intake air, reducing burned gas temperature for
any given mass of fuel and oxygen. It has been
successfully employed in the automotive
industry where good quality fuel is used but
marine diesel engine manufacturers claim that
even when the fuel has insignificant amounts of
sulphur, the practical application of EGR causes
unacceptable operational problems.
• Water Cooled Rest Gas (WaCoReG) -
Developed for slow speed engines, this system
utilises the same mechanism as an EGR system,
i.e. introducing some 'rest gas' into the
combustion space. In an engine with
electronically controlled exhaust valve timing it
is quite easy to leave some of the exhaust gas in
the cylinder. This obviously has a negative
impact on engine performance, however this
can be dramatically reduced by cooling the rest
gas with a water spray, in which case the rest
gas accounts for some of the NOx reduction and
the water spray for the rest.
• Humid Air Motor (HAM). Hot compressed air
from the turbocharger is led to a humidification
tower and exposed to a large surface area and
flushed with hot water. The water can be
heated by a heat exchanger connected to the
jacket cooling system or using an exhaust gas
boiler. The principle is the same as that
described under Combustion Air Saturation
System, CASS previously. One manufacturer
claims considerable success in service in
reducing NOx emissions with the added claim
of increasing the indicated power of the engine
at certain loads therefore reducing fuel
consumption hence proportionally reducing
CO2 emissions
The actual degree of NOx reduction varies from
10% to over 60%, depending on the engine type
and which of the above reduction methods are
adopted.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
2.5 Can the various Primary methods of
NOx reduction be combined?
Combinations of primary NOx reduction methods
are possible. Reduction of NOx in some medium
and high speed engines is achieved by exploiting a
combination of high compression ratio with
retarded fuel injection.
This calls for the engine to inject fuel late in the
cycle and over a short duration without destroying
performance.
2.6 What are Secondary NOx reduction
methods?
Secondary methods reduce NOx in the exhaust gas
by downstream treatment.
Selective Catalytic Reduction (SCR) is such a
system and can cut emissions by well over 90%
with figures of 98% NOx reduction being recorded.
2.7 How does the Selective Catalytic
Reduction (SCR) system work?
In an SCR system the exhaust gas, at a temperature
between 250 and 530°C, is mixed with ammonia
(commonly in the form of a solution of urea in
water). This introduces single atom nitrogen (N)
creating a reducing atmosphere before passing
through a special catalyst. The NOx is reduced to
harmless gaseous stable nitrogen (N2) and water.
The catalyst core is often composed of a heat
resistant ceramic honeycomb with a catalytically
active material, such as oxides of vanadium,
dispersed on its surface. The surface in contact
with the exhaust gas needs to be extremely large in
order for all the molecules of NOx and N to touch a
catalytically active site on the substrate. At the
same time the resistance to exhaust gas flow
created by placing the catalyst in the exhaust gas
path must be minimised to reduce excessive
pressure drops.
2.8 If Selective Catalytic Reduction (SCR)
has such an extremely high NOx reduction
efficiency why is it so rare in marine
applications?
There are many reasons contributing to the fact
that SCR’s have not been widely taken up for use
with marine diesel engines, the major ones are
listed:
• Large initial cost
• Large spatial requirements.
• Low efficiency
• High pressure drop
• Fouling tendency
• Resistance to poisoning
• Heat up time
• Recycling of used catalysts
• Safety aspects (handling ammonia)
• Availability
Probably the biggest disadvantage is the massive
dimensions of most present commercially available
SCR reactors and as such are often impractical to
retrofit to an existing marine installation.
As technology progresses SCR systems for the
marine environment are being further developed
and installed on vessels operating in places such as
Sweden where there is a distinct financial gain
from having extremely low NOx emission engines.
2.9 How does adding water to the fuel
reduce NOx emissions?
Water addition to the fuel is effective in reducing
NOx formation during combustion, mainly
because the water evaporates immediately upon
injection. This improves the intimate mixing of the
fuel and air and promotes a homogenous fuel - air
mixture. Evaporation of the water also reduces the
maximum combustion temperature.
Water emulsified with the fuel prior to injection
requires a significant increase in the fuel pump
capacity. Special precautions are necessary to keep
the water-fuel emulsion stable and prevent
corrosion of fuel system components.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
Water can also be added to the combustion space
through separate nozzles or by the stratified
segregated injection of water and fuel from the
same nozzle (direct water injection).
Some manufacturers consider direct water
injection preferable to the introduction of water as
an emulsified fuel. In order to reduce NOx
emissions significantly it is claimed that the
proportion of water in emulsified fuel must
approach 50%.
2.10 Are there any disadvantages in
introducing water into the combustion
process using fuel emulsification?
It is claimed that addition of water to the
combustion process has its drawbacks:
• The emulsion is not always stable and
variations in the fuel type may produce
different behaviour.
• Severe corrosion could be a problem if the
injection system is not flushed with clean fuel
before the engine stops.
• The emulsion lowers the energy content per
volume of mix and so the injection equipment
must be substantially enlarged to produce the
same power. This will increase the amount of
power absorbed by the injection equipment.
Another way of introducing water into the
combustion zone is by humidifying the scavenge
air as detailed in 2.4. Warm water is injected and
vaporised in the charge air increasing its absolute
humidity and reducing NOx emission formation
rates. In turbo-charged engines the parameters of
charge air humidity and temperature are obviously
important downstream of the charge air cooler.
2.11 How does Exhaust Gas Recirculation
(EGR) reduce NOx emissions?
Exhaust Gas Re-circulation (EGR) is a method of
modifying the inlet air to reduce NOx emissions,
an approach widely used in automotive
applications. Some of the exhaust gas is cooled and
cleaned before re-circulation to the scavenge air
side.
Its effect on NOx formation is partly due to a
reduction of the oxygen concentration in the
combustion zone and partly due to the content of
water and carbon dioxide in the exhaust gas.
Introduction of these dilutants reduces flame
temperatures by increasing the heat capacity of the
cylinder charge per unit mass of fuel. Although
EGR is an efficient method of reducing NOx
emissions (up to 60%) it is considered more
practical for engines burning ‘clean’ bunkers such
as low sulphur and low ash fuels, alcohol and gas.
Engines operating on high sulphur fuels could
suffer from corrosion of the turbochargers, intercoolers
and scavenging pipes.
Increased fuel consumption is also associated with
EGR due to the retarded heat release rate.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 l 2002 Questions and Answers
2.12 Can combinations of NOx reduction
methods be combined effectively?
Research by one manufacturer has shown that
substantial reductions in NOx (80%+) have been
obtained with only minor increases in fuel oil
consumption by using the following combination:
• modified fuel valve and fuel nozzle design with
• 50% water addition to the fuel (FEW),
• 20% Exhaust Gas Re-circulation (EGR)
• Reduced firing pressure by retarding timing
The effects of these modifications are shown :
Claimed effects of combining NOx reduction techniques
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Modification/combination
Relative NOx emissions
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1
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4 5
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
3. IAPP & EIAPP Certificates, Flag States, MARPOL Annex VI and the
NOx Technical Code.
3.1 What is MARPOL 73/78 Annex VI
Regulation 13 and the IMO NOx Technical
Code?
In September 1997 the International Maritime
Organisation (IMO) adopted, by means of a
Protocol, a new Annex to the MARPOL
Convention. The new Annex, Annex VI, is entitled
‘Regulations for the Prevention of Air Pollution
from Ships.’ The IMO also adopted the ‘Technical
Code on Control of Emission of Nitrogen Oxides
from Marine Diesel Engines’ (the NOx Technical
Code).
The Annex and the NOx Technical Code will
become mandatory when the required number of
Flag States become signatories to the protocol.
For compliance with Regulation 13 of the Annex all
diesel engines of 130 kW rated power and above
(except those solely for emergency use) installed in
ships constructed on or after 1 January 2000 are
required to meet certain Oxides of Nitrogen (NOx)
emission limits.
The NOx Technical Code establishes the
procedures for the testing, survey and certification
of diesel engines to ensure compliance with the
NOx emission limits (Regulation 13).
3.2 What is an IAPP certificate?
The International Air Pollution Prevention (IAPP)
certificate is issued to the vessel by the flag
Administration or an organisation authorised to
act on its behalf, after the owner demonstrates that
the vessel complies with all relevant requirements
under MARPOL Annex VI.
The IAPP is valid for five years, and is subject to
successful completion of the vessel’s initial and
intermediate surveys.
These certificates will not be issued until the Annex
enters into force under Article 15 of the MARPOL
Convention.
3.3 What is an EIAPP certificate?
The Engine International Air Pollution Prevention
(EIAPP) certificate is issued by an authorised
organisation for each applicable engine, engine
family, or engine group after the engine
manufacturer demonstrates that the engine
complies with the NOx limits set out in Regulation
13 of Annex VI.
The EIAPP certificate is good for the life of the
engine subject to correct maintenance or until it
undergoes a major conversion.
These certificates will not be issued until the Annex
enters into force under Article 15 of the MARPOL
Convention.
3.4 Can EIAPP certificates be issued even
though MARPOL Annex VI has yet to be
ratified?
At this time it is not possible to issue Engine
International Air Pollution Prevention (EIAPP)
Certificates. These can only be issued when
MARPOL Annex VI and the NOx Technical Code
are in force internationally. It is not possible to say
when they might come into force as it is dependant
on the required number of countries signing Annex
VI. Only a statement or certificate of compliance
with the NOx Technical Code can be issued at
present .
At MEPC 42 the International Maritime
Organisation (IMO) adopted a circular which, in
effect, says that diesel engines installed on ships
constructed on or after 1 January 2000 should have
certification for compliance with the NOx
Technical Code requirements.
Our information is that statements or certificates
issued by Lloyds Register (and it is assumed by
other IACS members) will be accepted by National
Authorities. These statements /certificates would
then be replaced by EIAPP Certificates issued on
behalf of the flag administration once Annex VI
and the NOx Technical Code come into force.
3.5 What is a Technical File?
The Technical File is a record containing all details
of parameters, including components and settings,
that influence the NOx emissions of the engine.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 l 2002 Questions and Answers
According to the NOx Technical Code, the
Technical File must contain the following
information;
• Identification of those components, settings and
operating values of the engine which influence
its NOx emissions,
• Identification of the full range of allowable
adjustments or alternatives for the NOx
sensitive components of the engine in order to
maintain compliance within the IMO limits,
• A full record of the relevant engine’s
performance, including the engine’s rated
speed and rated power;
• A system of on-board NOx verification
procedures to verify compliance with the NOx
emissions limits during on-board verification
surveys in accordance with chapter 6 of the
code;
• A copy of the emission test report used to
certify the engine
• If applicable, the designation and restrictions
for an engine which is a member of an engine
group or an engine family;
• Specifications of those spare parts/components
which, when used in the engine, according to
those specifications, will result in continued
compliance of the engine with the NOx
emission limits: and
• The EIAPP certificate or Statement of
Compliance, as applicable.
3.6 What is a ‘Record Book of Engine
Parameters’?
The Record Book of Engine Parameters is a
document for recording all parameter changes,
including components and engine settings, that
may influence NOx emissions. This is another
essential document for surveys and inspections
because it contains a record of adjustments to the
engine. At each survey the Record Book is
examined to ensure that no changes have been
made to the engine that might affect NOx
emissions.
Vessel owners must make sure the Record Book is
accurately maintained up to date. If the settings on
the engine do not match those in the Record Book,
an engine survey may include a more timeconsuming
investigation and, potentially, on board
measurement of NOx emissions.
3.7 Can LR accept NOx Certificates of
Compliance issued by other IACS
Classification Society's for engines that
are to be installed in LR classed when
requested to do so by the engine
builder/ship yard?
It is not the intention to accept unconditionally
certification by another IACS member, with regard
to NOx at this stage. This situation may change
when methods and requirements of the Flag
Administrations become clearer after ratification.
3.8 Can a body carry out NOx Emission
testing of an engine with their own
equipment and then certify that engine?
This would not be considered ethical. If the two
functions were fully separate then this may be
acceptable provided the chain of responsibility was
totally separate.
In general, a third party should be employed to
witness the testing and verify the accuracy of the
equipment.
This gives international credence to the testing
especially where the manufacturer may be
requesting certification from different flag
administrations.
3.9 When will MARPOL Annex VI and
the NOx Technical Code come into force?
Annex VI of MARPOL 73/78, as adopted by the
Protocol of 1997, contains regulations for the
prevention of air pollution from ships and includes
a resolution which introduces the NOx Technical
Code.
Under article 6 of the Protocol of 1997, Annex VI
will come into force 12 months after the date on
which not less than fifteen States, the combined
merchant fleets of which constitute not less than 50
per cent of the world’s merchant shipping, have
ratified it. Some countries have already ratified
whilst others are in the process of doing so.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
Under paragraph 2 of Resolution 2 to Annex VI the
NOx Technical Code will enter force, as mandatory
requirements, for all Parties to the 1997 Protocol on
the same date as Annex VI comes into force.
Therefore in spite of possible delays before Annex
VI comes into force, there will be retrospective
application of the nitrogen oxide limits to marine
diesel engines with a power output of more than
130 kW which are installed in ships, vessels or
offshore installations constructed on or after 1st
January 2000. The same limits will also apply to
marine diesel engines with a power output of more
than 130 kW, which undergo a major conversion
on or after 1st January 2000.
3.10 What is meant by a “major
conversion” as detailed in Annex VI?
“Major Conversion” means a modification of an
engine where:
• the engine is replaced by a new engine built on
or after 1st January 2000, or
• any substantial modification is made to the
engine, or
• the maximum continuous rating of the engine is
increased by more than 10%
3.11 What is meant by “substantial
modification”?
1.3.2 “Substantial modification of a marine diesel
engine means:
• For engines installed on ships constructed on or after
1st January 2000, substantial modification means
any modification to an engine that could potentially
cause the engine to exceed the emissions standards
set out in regulation 13 of Annex VI. Routine
replacement of engine components by parts specified
in the Technical File that do not alter emission
characteristics shall not be considered a “substantial
modification” regardless of whether one part or
many parts are replaced.
• For engines installed on ships constructed before 1st
January 2000, substantial modification means any
modification made to an engine which increases its
existing emission characteristics established by the
simplified measurement method in excess of the
allowances set out in 6.3.11 of the NOx Technical
Code. These changes include, but are not limited to,
changes in its operations or in its technical
parameters (e.g., changing camshafts, fuel injection
systems, air systems, combustion chamber
configuration, or timing calibration of the engine).
3.12 Will Annex VI Regulation 13 apply
to second-hand engines to be fitted on
existing vessels ?
Regulation 13(1)(a)(i) does not apply to secondhand
engines, which may have been overhauled
but not modified or the continuous rating is not
increased by more than 10 per cent, if they are
fitted to ships, vessels or offshore installations
constructed before 1st January 2000, as this would
not constitute a major conversion under Regulation
13(2)(a)(i). Regulation 13 does apply to any engine
with a power output of more than 130kW which is
installed on a ship constructed on or after 1
January 2000.
Note: All ships will require to be issued with an
IAPP certificate once Annex VI is ratified.
However, only ships constructed after January 1st,
2000 will require to demonstrate compliance with
Annex VI, Regulation 13, unless the engine
undergoes a major conversion.
3.13 What is the procedure for dealing
with enquiries on the certification of
diesel engines for compliance with
MARPOL Annex VI and the NOx
Technical Code?
If requested by an owner, builder or engine
manufacturer Lloyd’s Register can carry out the
required technical file approval, testing and
certification for compliance with the NOx
Technical Code and regulation 13 of Annex VI.
All enquiries regarding certification of diesel
engines for compliance with the NOx Technical
Code must be forwarded to MSG, Engineer
Services (ES). ES will advise on the procedures for
technical file approval and testing requirements.
Unless other wise advised by ES, engine emission
tests are NOT to be undertaken without being
contacted. NOx emission testing can only be
witnessed by authorised surveyors
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
3.14 Which flag states have authorised
Lloyd’s Register (LR) to issue NOx
certification?
Lloyd's Register (LR) has contacted over 100
administrations seeking authorisation to issue NOx
certification on their behalf.
Many Administrations have intimated that a LR
certificate will be acceptable to them until such
time as MARPOL 73/78 Annex VI and the NOx
Technical Code come into force. At that time the
LR certificate will then be used to issue an EIAPP
certificate either by LR on behalf of the
administration or by the administration
themselves.
Where an administration has instructed LR to issue
certificates on behalf of the administration the
Government Title will be referenced on the LR
Certificate.
The NOx authorisations have been included in the
Flag Administration data on the LR web site;
Marine/External Affairs/Library "Country Files".
This is regularly up dated.
In general it is our understanding that during the
intervening period leading up to ratification the
majority of Flag Administrations will accept tests
and certification issued by LR for NOx compliant
marine diesel engines.
3.15 Does MARPOL Annex VI apply to
offshore installations?
MARPOL 73/78 Annex VI is applicable to all ships
of 400 tonnes gross and above and to offshore
installations which includes fixed and floating
drilling rigs and other platforms .
3.16 Where can the texts of Annex VI and
the NOx Technical Code be found?
The IMO have published the texts of MARPOL
Annex VI and the NOx Technical Code in a single
publication. The IMO sales number is IMO-664E,
current price £14.00.
3.17 What are LR’s fees for NOx
certification?
LR’s services associated with NOx emissions
certification will be charged on the basis of a LR fee
for the review of Technical File, assessment of the
test reports and issue of a certificate, together with
the fees for inspection and witnessing of NOx
emission verification tests/survey.
Fee quotations are based on the submitted
documentation being complete, and being
submitted in the English language, or a language
acceptable to LR. Translation costs may be
incurred for documentation submitted in other
languages. Where translation charges are
necessarily incurred for technical documentation,
such additional charges will be invoiced at cost.
For initial, periodical and renewal surveys, a
quotation will be made upon acceptance of an
application.
Should a client withdraw his application for
certification, for whatever reason, LR reserves the
right to charge fees for costs already incurred.
3.18 What is the period of validity of the
pre-certification certificate ?
The pre-certification certificate remains valid for all
engines validated as manufactured in accordance
with the Technical File for the Administration
under whose authority it is issued.
Certificates or Statements of Conformity will
require to be replaced with an EIAPP Certificate on
Annex VI entering into force.
EIAPP Certificates are to be issued by or on behalf
of the respective Flag Administration.
3.19 What are the allowable NOx
emission limits as stated in Annex VI
regulation 13?
• 17.0 g/kWh where n is less than 130 rpm
• 45.0*n(-0.2) g/kWh where n is 130 or more but
less than 2000 rpm
• 9.8 g/kWh where n is 2000 rpm or more
where n is the rated engine speed (crankshaft
revolutions per minute).
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
The maximum values of 17.0 and 9.8 g/kWh and
the simple function of n can be better visualised
graphically as shown:
Max NOx Emission limits as a function
of rated speed
8
9
10
11
12
13
14
15
16
17
18
0 500 1000 1500 2000 2500
Rated engine speed (crankshaft rpm)
Maximum NOx limit
(g/kWh)
3.20 Which States have already ratified
Annex VI? Is there any mechanism to
identify the impediments to entry into
force?
As of early 2001 only three States have ratified
Annex VI, namely Norway, Sweden and Singapore
representing nearly 9% of the gross world tonnage.
Conference resolution 1 "INVITES, if the conditions
for entry into force of the 1997 Protocol have not been
met by 31st December 2002, the Marine Environment
Protection Committee (MEPC), at its first meeting
thereafter, to initiate, as a matter or urgency, a review to
identify the impediments to entry into force of the
Protocol and any necessary measures to alleviate those
impediments".
3.21 When a ship is classed by LR and the
ship owner requests NOx certification for
engines installed on board, do certificates
have to be issued by LR or are certificates
issued by other classification societies
acceptable?
There are two types of certificate that may be
issued for compliance with MARPOL Annex VI:
• Certification for diesel engines, above 130kW
which are not used for emergency purposes,
after satisfactory testing for compliance with
the NOx Technical Code. This is carried out on
the test bed to demonstrate that the NOx
emissions generated by the engine are within
the limits set out in MARPOL Annex VI,
Regulation 13. Marine diesel engines installed
on board a new ship after 1st January 2000 must
be certified in compliance with Regulation 13 of
MARPOL Annex VI and the NOx Technical
Code. Until MARPOL Annex VI is ratified, this
will be known as a Certificate or Statement of
Compliance. After ratification it will be termed
an Engine International Air Prevention
Pollution (EIAPP) certificate.
• Once MARPOL Annex VI is ratified, then
International Air Prevention Pollution (IAPP)
certificates will become mandatory. Until then
they are not required unless a specific flag
administration makes it mandatory for ships
registered by them. The IAPP certificate covers
the following items as applicable to the type of
ship being certified: Ozone Depleting
Substances, Nitrogen Oxides (NOx), Oxides of
Sulphur (SOx), Volatile Organic Compounds
(VOCs), Shipboard Incineration and Fuel Oil
Quality.
Certificates are issued for and on behalf of the flag
administration with whom the vessel is registered,
similar to current statutory certification.
Whether an EIAPP certificate issued by one
classification society is acceptable to another is a
matter for the flag administration.
This is a subject being discussed within the
International Association of Classification Societies
(IACS) Working Group on Exhaust Emission
Controls forum but at this time there is no clear
consensus on the procedure to be adopted.
The on-board surveys and issue of the IAPP
certificates would be carried out by the
classification society who has responsibility for the
issue of the ship’s statutory certificates. Since the
Society has been appointed to act for the
Administration, they cannot delegate that
authority to an other third party.
In general, since LR is acting for and on behalf of
the various Flag Administrations LR would prefer
to witness the testing to allow them to meet their
commitment to the authority. However, where the
Parent engine EIAPP certificate has been issued by
another body recognised by the Flag
Administration, LR could accept this to certify
member engines subject to certain conditions being
met.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 ul 2002 Questions and Answers
4. On-Board Verification Procedures
4.1 What is an On-Board Verification
Survey?
Each diesel engine subject to the requirements of
MARPOL 73/78 Annex VI Regulation 13 shall be
subject to an initial survey, an intermediate survey
and a periodical survey as part of the ships IAPP
survey and certification regime. The On-board
Verification Survey is detailed in the approved
Technical File. It describes the method for
confirming the engine remains in compliance with
the NOx emission limits and forms part of the
ship's IAPP survey.
After a pre-certified engine is installed on-board a
ship, an initial installation verification survey is
carried out to confirm that the engine remains in
compliance with the NOx emission limits. The onboard
verification survey is not mandatory until
MARPOL Annex VI comes into force when each
ship is required to be surveyed for the issue of and
IAPP certificate.
4.2 What methods are available for the
On Board Verification Survey ?
Surveys will be conducted on board using one of
the three methods of NOx Verification described in
sections 2.4.2 to 2.4.6 of the NOx Technical Code;
2.4.4 On- board NOx verification procedures shall be
determined by using one of the following methods:
• Engine parameter check in accordance with section
6.2 of the NOx Technical Code to verify that an
engine’s component, setting and operating values
have not deviated from the specifications in the
engine’s Technical File;
• Simplified measurement method in accordance with
section 6.3 of the NOx Technical Code , or
• Direct measurement and monitoring method in
accordance with 2.3.4, 2.3.5, 2.3.7, 2.3.8, 2.3.11 and
5.5 of the NOx Technical Code .
4.3 Who decides which system of On-
Board Verification is to be used?
Making reference to Chapter 6 of the NOx
Technical Code :
Onboard the vessel it is the owner who decides the
system to be followed for the onboard verification.
The engine manufacturer has the responsibility of
preparing and documenting an engine survey
system to allow the ship owner to use the system
he so desires.
The system is to be prepared by the engine
manufacturer and submitted to the
Administration, or the organisation acting on their
behalf, for acceptance.
4.4 What is involved in the Engine
Parameter Method?
The engine parameter method of verification
documentation must form part of the Technical
File.
The survey process detailed here is for guidance as
to the typical information to be included in the
documentation.
This method is a check to verify that the
components, settings and operating values of the
engine once installed on the vessel remain the
same as those recorded in the Technical File at the
time of the pre-certification.
It may be carried out on engines which have a precertificate
(EIAPP certificate), those which have
been certified after installation (IAPP certificate)
and after modifications or adjustments since the
previous survey.
The surveyor with the assistance of a check sheet
will survey the following and confirm they remain
within the allowable range specified in the
Technical File;
• Review existing certificates and documentation
on-board the ship.
• Review the record book of engine parameters
noting all recorded changes and confirming
their acceptability or otherwise with the
Technical File.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 200􀀅􀀆􀀇􀀈 2 Questions and Answers
• Inspect engine components affecting NOx
emission limits and verify they are correct for
the engine type.
• Inspect and test the adjustable settings of the
engine, as applicable
• Review and test, where applicable, the engine
operating values.
• Check NOx emission treatment devices or
systems, where appropriate, and their
consumption measurement devices,
• Verify electronic engine management systems
against original settings, where relevant.
• Complete the check list for the ship and submit
with the inspection report to appropriate LR
office for review and issue of the appropriate
certification.
4.5 Are deviations from test cycles
allowable when using the simplified
measurement method of on-board
verification?
Where maximum or minimum loads cannot be
attained or where barred speed ranges preclude
operation the test procedure proposal has to based
on the engine manufacturer’s recommendations
but be as close as possible to the test cycles defined
in chapter 3 of the NOx Technical Code. The
proposal would still have to be approved by the
administration.
6.3.9.2 Engine operation on board under a test cycle
specified in 3.2 may not always be possible, but the test
procedure shall, based on the recommendation of the
engine manufacturer and approval by the
Administration, be as close as possible to the procedure
defined in 3.2. Therefore, values measured in this case
may not be directly comparable with test bed results
because measured values are very much dependent on
the test cycles.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 200􀀅􀀆􀀇􀀈 2 Questions and Answers
5. Engine Specifics
5.1 If an engine is rated above 130 kW but
will NOT be fitted on an Annex VI ship
does it need to comply?
From an engine perspective Annex VI applies to all
diesel engines with a rated power of more than 130
kW which are installed on ships constructed on or
after 1 January 2000 and every diesel engine with a
rated power of more than 130 kW which
undergoes a major conversion on or after 1 January
2000.
From a ship perspective Annex VI applies to all
ships, of 400 gross tonnnes and above which
operates under a Flag Administration that has
ratified the Annex.
Note: Administrations who have ratified Annex VI
are required to implement the requirements to
their own flag ships and to all other flag ships
operating in their waters and ports subject to the
exemption stated in the Annex.
However, ships under 400 gross tonnes are only
subject to the survey requirements at the discretion
of the administration. The actual text reads:
“In the case of ships of less than 400 gross tonnage, the
Administration may establish appropriate measures in
order to ensure that the applicable provisions of this
annex are complied with.”
In summary, with specific reference to recreational
craft, the requirements of Regulation 13 apply to
all vessels, however only vessels over 400 gross
tonnage would be subject to the survey
requirements of Regulation 5. Vessels below 400
gross tonnage would not be subject to the survey
requirements of Regulation 5 unless the local
Administration establishes the necessary systems.
Reference should also be made to Regulation
13(1)(c) which allows the Administration to permit
a derogation to ships that are only engaged in
voyages between ports within the territory of that
Administration. This does not only mean that an
and Administration could have a lower, or even no
limit values for exhaust emissions for its own intranational
ships, but could actually make stricter
provisions than those of Regulation 13 for its own
flag vessels.
5.2 Does MARPOL Annex VI apply to
diesel driven cargo pumps having a rated
power greater than 130 kW?
Yes. All marine diesel engines with a power rating
greater than 130 kW, which are not used
specifically for emergency purposes (i.e.
emergency generator engines), are required to be
certified in compliance with the NOx Technical
Code as satisfying the NOx limits as stated in
MARPOL Annex VI, Regulation 13. This applies to
engines installed on new buildings or existing
ships from 1st January 2000.
1.2.1 The NOx Technical Code applies to all diesel
engines with a power output of more than 130 kW
which are installed, or are designed and intended for
installation, on board any ship subject to Annex VI,
with the exception of those engines described in
paragraph 1(b) of regulation 13.
MARPOL Annex VI regulation 13 (1)(b)(i) states:
This regulation does not apply to emergency diesel
engines, engines installed in lifeboats and any device or
equipment intended to be used solely in case of an
emergency.
Where engines are not solely for emergency use
(i.e. a first start diesel generator which may also be
used to supply part of ships electrical load under
certain condition), they are to be subject to the
requirements of this Regulation.
5.3 What is an ‘installed engine’?
‘Installed’ relates only to permanently installed
engines, that is those as given on the ship’s records.
Packaged and other temporally installed engines
should not be included.
5.4 Can an engine having a higher rating
and more cylinders be certified based on a
parent tested for a lower rating and/or
number of cylinders?
The Group and Family engine concepts are
available to enable serially manufactured engines
to be certified against an approved Parent engine
for that Group/Family in order to reduce the
amount of emissions testing to a minimum.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
The allowable engine types/configurations/rated
powers and rated speeds have to be approved by
the administration and clearly stated in the Parent
Engine Technical File. The chosen Parent Engine
for the Group/Family must be shown to be the
highest NOx emission engine in that
Group/Family. This means that any engine
type/configuration/rating of a Group/Family
Member Engine must be shown either by prior
testing or other means to be a lower NOx emission
engine than the Parent.
Justification must be supplied as to why a
subsequent engine with a higher rating or
increased number of cylinders is a lower NOx
emission engine than the Parent Engine.
The main criteria in this justification would be a
lower fuel delivery rate per cylinder.
Other criteria that may be supplied to justify an
engine as a Group/Family Member may include;
• lower mean effective pressure
• lower maximum cylinder peak pressure
• lower compression pressure ratio
• lower charge air pressure
• lower charge air temperature
5.5 Heavy Fuel Oil (HFO) is used in
service in most large marine diesel engines
yet the testing requirements detail the use
of Marine Diesel Oil (MDO) to be used
during the NOx emission test on the test
bed. How can the emissions under test
bed conditions therefore be related to
those under normal in service operation?
The NOx Technical Code states:
5.3.1 Fuel characteristics may influence the engine
exhaust gas emission. Therefore, the characteristics of
the fuel for the test shall be determined and recorded.
Where reference fuels are used, the reference code or
specifications and the analysis of the fuel shall be
provided.
5.3.2 The selection of the fuel for the test depends on
the purpose of the test. Unless otherwise agreed by the
administration and where a suitable reference fuel is not
available, a DM-grade marine fuel specified in ISO
8217, 1996, with properties suitable for the engine type,
shall be used.
If an engine is capable of residual fuel operation, it
will have been decided early in the planning
process whether residual fuel oil or gas oil is to be
used. As stated in the NOx Technical Code, in the
absence of a suitable reference fuel the requirement
is simply that the fuels should conform to, and be
tested to ensure compliance with ISO 8217.
Most commercial gas oils conforming to ISO 8217
DMA or DMB grades are adequate reference fuels
in that the results from different tests can be
comparable. There is therefore a requirement that
engines which will subsequently only burn
residual fuel oil should be initially tested using gas
oil. The use of a residual fuel oil in such engines
would give results closer to those which would be
encountered in service but the wide quality
variations possible would create questionable
repeatability of the results. It should be noted that
ignition quality and fuel bound nitrogen can have
a significant effect on the overall in-service
emissions.
5.6 Due to technical reasons a Family
engine has to be modified before supply to
a vessel. A different turbocharger has been
fitted. Can this engine still be certified as
a Family member and if so what is the
procedure?
The procedure would be as follows:
• Submit details of the turbocharger with
reasons why it is an acceptable alternative for
the approved NOx compliant diesel engine.
Where verifying test results are available these
should be submitted as part of the evidence.
• The documentation will be reviewed and
approved if found acceptable. This approval
will form an addendum to the original
Technical File to which it is to be attached
certifying it as an alternative turbocharger for
that series of engines.
• A copy of the approval and turbocharger
information should also be provided for
attachment to the engine Technical Files to
form part of the on board engine parameter
check method information.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 200􀀅􀀆􀀇􀀈 2 Questions and Answers
5.7 A main propulsion engine is to be used
with a controllable pitch propeller (CPP).
This configuration has two different
operating modes in normal service. At
high speed the engine speed remains
constant and the propeller pitch varies. At
low speed the propeller pitch is fixed and
the engine speed is varied. Which test
cycle is applicable?
It must be understood that the test cycle applied
should be in accordance with the normal service
condition of the engine. In standard CPP
configurations engine speed is constant and the E2
test cycle would be applicable. This configuration
would invariably allow the capability to ‘fix’ the
CPP pitch and operate the engine at variable speed
as an emergency measure (in the case of a CPP
failure). This condition falls outside the definition
of normal service and therefore there is no
requirement to test the engine in accordance with
the E3 cycle.
In cases where both configurations are designed as
‘normal service’ BOTH test cycles (E2 and E3)
must be applied during pre-certification testing.
The engine would then be provided with a
certificate covering each cycle respectively.
5.8 Two identical engine types are to be
installed on a twin skeg ship. The only
difference between them is the direction of
rotation (‘mirror engines’). Will the
engine with different rotation from the
Parent Engine be required to undergo
further NOx testing?
There is no requirement by LR to emission test an
engine with opposing rotation to that of a
previously NOx certified Parent Engine. This is on
the condition that the engine is equipped with
identical NOx sensitive components to those fitted
on the Parent Engine and all settings and
adjustments are within the approved ranges as
defined in the Parent Engine Technical File.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 l 2002 Questions and Answers
6. Conformity of Production (COP)
6.1 What is the purpose of the
Conformity of Production procedure?
What are the roles of the engine
manufacturer, ship owner and surveyor?
This relates to engines that are members of either a
“family” or a “group” which are serially produced
and are intended for compliance with the NOx
Technical Code. The manufacturer is required to
implement an approved control procedure which
will ensure each subsequent engine is assembled
using identical parts to those installed in the Parent
engine giving a presumption of conformity with
MARPOL Annex VI, Regulation 13, NOx Emission
limits. This allows the worst case i.e. highest NOx
producing engine, termed a “Parent engine”, to be
tested to reduce the number of engine tests
required.
The production control system must be in place
before component manufacturing commences to
ensure each is to the same design and marked with
a unique identifier.
The attending surveyor monitors the production to
confirm the assembly of the final engine and that
the control system is being implemented
effectively. After final assembly, the surveyor
issues a Verification of Conformity report for the
engine.
For main and auxiliary engines, this monitoring
can be incorporated into the normal classification
inspection procedure. However, for the smaller
massed produced engines the monitoring can be
based on a suitable quality scheme (LR Quality
Scheme for Machinery), in view of the volume
produced. Reference should be made to the LR
guidance document 'Conformity of Production
procedure' for further information.
The ship owner's role is to purchase a NOx
certified engine and to maintain it in compliance
with the NOx Emission limits. Thus, during
manufacture he must not request modifications
which would place the engine outside the limits
unless it is to be re-certified.
6.2 What is a Conformity of Production
Verification Report?
This is a report prepared by the attending surveyor
verifying that the subject ‘series produced’ engines
have been manufactured from compliant
components as identified in the Parent Technical
File in accordance with the manufacturers
approved Conformity of Production procedures.
The form is prepared for each engine or series of
engines and forwarded to the approval office as
part of the approval procedure.
The NOx Verification of Conformity Report
provides the approval office with the necessary
confirmation of the engine(s) presumption of
conformity with the Parent Engine NOx emission
limits allowing the submitted Technical Files to be
verified and approved.
Typical form of a NOx Verification of Conformity
report:
􀀅􀀆􀀇􀀈 Date
Report No.
Office
NOx VERIFICATION OF CONFORMITY REPORT
Series Produced Marine Diesel Engines
Compliance with
NOx Emission Limits
This is to certify that the following Marine Diesel Engine(s) components and markings
were verified as complying with those detailed in the approved Parent Engine
Technical File during manufacture and assembly.
Engine Type :
Serial No(s) :
Date of Manufacture :
Parent Engine Type :
Parent Engine Technical
File Approval No. :
Surveyor yo Lloyd’s Register
Ver_con.doc 8.99 Rev01
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
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6.3 At what stage should the Conformity
of Production procedure be put in place?
The engine builder should be encouraged to have a
Conformity of Production procedure in place
before testing the Parent engine. Normally this
means incorporating the NOx controls into his
existing engine production procedures.
This ensures that he can easily demonstrate
through this system that the NOx sensitive
components in subsequent engines, after the
parent, are the same as those components in the
parent.
Such a system is designed to reduces any necessity
to test subsequent engines.
6.4 Should the Conformity of Production
procedure be included in the Technical
File?
The Conformity of Production procedure is to be
submitted to the Administration for review and
approval as part of the certification process. A
copy of this document is retained by the
Administration together with the Technical File
and any other ‘additional information’ submitted
at the review stage. It is not required to form part
of the Technical File as supplied with the engine.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 l 2002 Questions and Answers
7. Pre-Certification Testing
7.1 What is Pre-certification testing?
This is undertaken on the test bed at the engine
manufacturer’s works to ensure that the engine as
designed and equipped complies with the NOx
emission limits contained in regulation 13 of
Annex VI. Under certain circumstances this may
be conducted on board the ship after installation
and prior to entering service and issue of the IAPP
certificate.
On completion of the approval process LR will
issue either an LR Certificate or Statement of
Compliance or an Engine International Air
Pollution Prevention (EIAPP) Certificate where
authorised by the Administration once Annex VI is
ratified.
7.2 How much time should be allocated
to a Parent Engine test bed programme?
Who should attend?
Sufficient time needs to be allocated in the Parent
Engine test bed programme to allow for the
inspection of the engine to ensure that it conforms
with the proposed Parent Engine design, fit and
adjustment. The test bed equipment will need to be
assessed for compliance with the NOx Technical
Code requirements, this would include a review of
calibration certification for the analysers and other
measurement equipment.
The actual parent engine test would be expected to
take from 3-8 hours under the specified Code
requirements. From LR’s viewpoint this attendance
will be undertaken only by Surveyors with the
necessary experience, training and authorisation.
7.3 On fuel testing.
5.3.2 The selection of the fuel for the test depends on the
purpose of the test. Unless otherwise agreed by the
Administration and when a suitable reference fuel is not
available, a DM-grade marine fuel specified in ISO
8217, 1996, with properties suitable for the engine type,
shall be used.
Oil fuel used for the test is to be analysed for each
of the parameters in the ISO 8217 specification plus
carbon, hydrogen and nitrogen.
They are not required to be tested for oxygen
content since this is taken as zero.
When testing for ISO 8217 grades DMA and DMB
the ignition performance parameter is strictly to be
determined as Cetane Number not Cetane Index
since the latter cannot determine the effect of any
cetane improvers.
7.4 On exhaust gas analytical systems.
5.9.2.1 An analytical system for the determination of
the gaseous emissions (CO, CO2, HC, NOx, O2) in the
raw exhaust gas shall be based on the use of the
following analysers:
• Heated Flame Ionisation Detector (HFID) for the
measurement of hydrocarbons;
• Non-Dispersive Infra-Red (NDIR) analyser for the
measurement of carbon monoxide and carbon
dioxide;
• Heated ChemiLuminescent Detector (HCLD) or
equivalent analyser for the measurement of nitrogen
oxides; and
• ParaMagnetic Detector (PMD), ElectroChemical
Sensor (ECS) or ZiRconium DiOxide (ZRDO)
sensor for the measurement of oxygen.
The NOx Technical Code does not provide for
alternative analyser principles to be used (unlike
ISO 8178). In order to avoid, at least some of, the
possible problems with the future reproducibility
of test results only the analytical principles as
given will be acceptable, i.e. only
chemiluminescence analyser is to be used for NOx
measurements
7.5 On non standard air inlet and exhaust
systems.
5.9.1.2 The settings of inlet restriction and exhaust back
pressure shall be adjusted to the upper limits as specified
by the manufacturer in accordance with 5.2.4 and 5.2.5,
respectively.
In order to meet the requirements of 5.2.4 the inlet
air system should be adjusted, where a nonstandard
air inlet system is to be used, to give the
minimum inlet depression i.e. maximum absolute
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀅􀀆􀀇􀀈 2002 Questions and Answers
pressure post filter or at turbo-blower compressor
inlet.
In order to meet the requirements of 5.2.5 the
exhaust system should be adjusted, where (as
would more normally be the case than for the inlet
air system) a non-standard exhaust system is to be
used, to give the minimum pressure post turboblower
turbine exhaust.
7.6 On intermediate zero and span checks
5.9.9 After the emission test, the calibration of the
analysers shall be re-checked using a zero gas and the
same span gas as that used prior to the measurements.
The test shall be considered acceptable if the difference
between the two calibration results is less than 2%.
Analysers may be subject to intermediate zero and
span checks (i.e. between test load points), in
which case the drift allowance is to be considered
between two consecutive checks. The span and
zero may with some instruments be checked
without necessarily re-setting the analysers, in
other cases such checks will automatically reset the
values and hence could mask unacceptable
performance.
7.7 On alternative test standards for
Engine Family Certification.
4.3.10.5 If the parent engine of an engine family is to be
certified in accordance with an alternative standard or a
different test cycle than allowed by the NOx Technical
Code, the manufacturer must prove to the
Administration that the weighted average NOx
emissions for the appropriate test cycles fall within the
relevant limit values under regulation 13 of Annex VI
and the Code before the Administration may issue an
EIAPP certificate.
The use of alternatives to those given in the Code,
(i.e. CIMAC, national standards) would not be
considered acceptable. Every effort should be
made to adhere closely to the requirements as
stated in the NOx Technical Code and not to
introduce other test methods into the approvals
process.
Even in terms of the test cycle, ISO 8178 is specific
as to the order of the load points although it should
be understood that this is principally related to the
effect of load cycle order on hydrocarbon and
particulate emissions.
If alternative methods etc. were to be adopted it
would remain necessary for the test condition
parameter to remain valid and that, as a minimum,
the data required by the NOx Technical Code be
obtained - under survey conditions.
7.8 On the Test Condition Parameter and
test validity for engine family approval
5.2.1 Parameter fa shall be determined according to the
following provisions:
For naturally aspirated and mechanically supercharged
engines:
f
P
T
a
s
= a

 

 

 

 
99
298
0.7
For turbocharged engines with or without cooling of
intake air:
f
P
T
a
s
= a

 

 

 

 
99
298
0.7 1.5
Where Ps is dry atmospheric pressure (kPa) and Ta is the
absolute temperature of intake air (K).
For a test to be recognised as valid, parameter fa shall be
such that:
0.98≤f ≥1.02 a
It is stressed that this requirement applies only to
Family Parent Engine emission tests.
The test condition parameter must be retained
within the required range across the whole of the
engine test period
Barometric pressure and ambient air temperature
readings should be entered as whole numbers only
with the result reported to the second decimal
place.
At the Marine Environment Protection Committee
(MEPC) 44th session it was agreed to approve a
proposed amendment to paragraph 5.2.1 of the
NOx Technical Code. The MEPC drafting group in
their report MEPC 44/WP.5 noted that it may not
be possible, due to engine size, to provide test
facilities where barometric pressure, temperature
and humidity of the intake air can be controlled to
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
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maintain the ‘fa’ factor within the range 0.98 <>
1.02. In consequence, the test for engine family
approval may only be possible for a limited period
during the year. The approved amendment states
that the following statement is to be added to the
end of paragraph 5.2.1:
“If, for evident technical reasons, it is not possible to
comply with this requirement, fa shall be between 0.93
and 1.07.”
This amendment was approved but will not be
adopted until Annex VI comes into force.
To allow uniform application of the NOx Technical
Code, and to assist Administrations in certifying
engines in accordance with it, this amendment is
recommended to be used prior to its date of entry
into force.
7.9 Who decides which method of NOx
calculation is to be used?
The responsibility to produce calculation results
lies with the engine manufacturer, or persons
nominated by himself to act on his behalf, with
regard to testing.
It is the role of the Flag State Administration, or
Classification Society acting on their behalf, to
witness the testing and validate results and
calculations. LR’s validation, to date, has shown
no significant divergences from the requirements
of the NOx Technical Code.
7.10 Many auxiliary marine diesel
engines are coupled to alternators and
installed as generating sets. Can this
alternator be used on the test bed as the
load dynamometer?
The NOx Technical Code is written for testing with
a dynamometer since in most instances it is not
possible to operate with the driven equipment
installed.
Where it is possible to carry out testing in the
completed condition, such as with the generator
installed, then it is acceptable to test in this
condition provided the required test (e.g. D2) may
be followed.
The alternator efficiency is normally evaluated at
the alternator trials. It is therefore not necessary to
evaluate the efficiency during the NOx emission
testing. Calculation using the manufacturer’s value
is acceptable.
7.11 The NOx Technical Code states
testing is to be undertaken with a sea
water temperature of 25°C. What does
this mean?
This section of the NOx Technical Code describes
the procedures for NOx emission measurements on
a test bed concerning only engines with charge air
cooling:
5.2.2.2 All engines when equipped as intended for
installation on board ships must be capable of operating
within the allowable NOx emission levels of regulation
13(3) of Annex VI at an ambient seawater temperature
of 25°C. 25°C seawater temperature is the reference
ambient condition to comply with the NOx limits. An
additional temperature increase due to heat exchangers
installed on board, e.g., for the low temperature cooling
water system, shall be taken into consideration.
The fresh water cooler outlet temperature, and
hence the charge air cooling capability, must be
based on the inlet temperature of 25°C for the FW
cooler coolant.
For the test bed measurements this will require the
primary cooling circuit temperature to be suitably
adjusted
7.12 It is sometimes difficult to simulate
the required 25°C sea water temperature
due to the limitations of the cooling water
supply at the factory. Can the test be
performed at a higher temperature?
It must be understood that the seawater
temperature shall not be lower than 25°C for the
pre-certification testing as reduced temperatures
result in reduced NOx emission values.
It is acceptable to allow a higher temperature at the
test bed as long as it maintains the engine at
normal operating temperatures as specified by the
manufacturer and also that he is aware that the
measured NOx value will be higher.
This temperature should also be recorded in the
test report.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
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7.13 What are the requirements
concerning the design of the exhaust gas
sampling probe? In the LR Precertification
checklist it states that the
‘maximum sensor length in exhaust trunk
should be 0.75 times the exhaust
diameter’. Does this apply to multi-holed
sensors?
The NOx Technical Code does not specify the type
of sampling probe that should be fitted during the
NOx emission pre-certification test. The test
procedure as stated in the NOx Technical Code is
based on the British Standard EN ISO 8178-1:1996
(Reciprocating internal combustion engines -
Exhaust emission measurement; Part 1 Test-bed
measurement of gaseous and particulate exhaust
emissions). This standard recommends a stainless
steel, straight, closed-end, multi-hole probe:
“The inside diameter shall not be greater than the inside
diameter of the sampling line. The wall thickness of the
probe shall not be greater than 1mm. There shall be a
minimum of 3 holes in 3 different radial planes sized to
sample approximately the same flow. The probe must
extend across at least 80% of the diameter of the exhaust
pipe.
LR will accept an open-ended sampling probe on
the condition that it samples a representative gas
sample and therefore the open end should be
located sufficiently near the exhaust pipe axial
centre-line to negate the effects of sampling
boundary layers of gas from the internal surface.
The maximum figure of 75% penetration of the
exhaust pipe diameter stated in the precertification
checklist would facilitate this
requirement and therefore would only apply to
open ended sampling probes.
7.14 Why is the location of the sampling
probe relative to the engine and exhaust
gas system exit so important?
5.9.3.1 The sampling probes for the gaseous emissions
shall be fitted at least 0.5m or 3 times the diameter of the
exhaust pipe – whichever is the larger – upstream of the
exit of the exhaust gas system, as far as practicable, but
sufficiently close to the engine so as to ensure an
exhaust gas temperature of at least 70°C at the probe.
The gaseous emission samples are required to be
taken from a point at least 0.5m or 3 times the
diameter of the exhaust pipe – whichever is the
larger – upstream of the exhaust gas exit to avoid
possible dilution of the exhaust gas sample by air
streams blowing across the atmospheric outlet.
The specified minimum gas temperature of 70°C at
the sampling probe is stated to avoid any
significant condensation of hydrocarbon (HC)
material in the section of the exhaust system prior
to the probe. At lower temperatures some of the
carbon material present (which would have
registered as part of the HC emissions at higher
temperatures) would be lost from the system.
Typically the sample will be drawn from a point
closer to the turbocharger outlet than exhaust
system exit to atmosphere, resulting in gas sample
temperatures above 70°C to negate problems with
HC condensation.
To prevent the condensation of water vapour,
nitrogen dioxide (NO2), and some of the HC
species present, both the gas filter and the line
used to transfer the sample down to the analysers
should be heated, typically being maintained at
190°C.
7.15 How should the exhaust gas sample
be taken in ‘Vee’ engine configurations ?
5.9.3.2 In multi-cylinder engines having distinct groups
of manifolds, such as in a “Vee” engine configuration, it
is permissible to acquire a sample from each group
individually and calculate an average exhaust emission.
Other methods which have been shown to correlate with
the above method may be used. For exhaust emission
calculation, the total exhaust mass flow must be used.
When an engine is configured with distinct groups
of exhaust manifolds the practice of simply
connecting the gas sample hoses together using 'y'
connectors would not necessarily give a
representative sample of the engine in that exact
balance between each manifold group is assumed.
A sample must be acquired individually from each
manifold group and the results mathematically
averaged.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
Engines Jul 􀀆􀀇􀀈 ul 2002 Questions and Answers
8. Parent, Family and Group Engine Concepts
8.1 What are the engine Family and
engine Group concepts?
Engines may be individually tested to demonstrate
that they satisfy the MARPOL Annex VI
Regulation 13 NOx limits.
Alternatively, a manufacturer may nominate a
Parent Engine to be tested as representative of an
engine family or engine group member to avoid
testing every engine which is intended to be
serially produced in that range.
The engine family concept may be applied to
series produced engines which have similar NOx
emission characteristics where no modifications or
adjustments which would affect the NOx
emissions are required when installed on board a
ship. Where adjustable features are provided (e.g.
for balancing cylinder peak pressures and
individual cylinder exhaust gas temperatures) they
are to be such that no setting, or combinations of
settings, can adversely affect the engine’s NOx
emissions. For engines within a particular family
the applicable characteristics detailed in 4.3.8 of the
NOx Technical Code should be common to those
engines.
The engine group concept may be applied to
similar type engines which require minor
adjustment or modification during installation or
in service on board a ship but whose NOx emission
will still remain within the NOx emission limit for
the engine. These engines are normally series
produced in low numbers such as large powered
propulsion engines.
For engines within a particular group, the
applicable characteristics as detailed in chapter
4.3.8 of the NOx Technical Code as well as those
parameters and specifications indicated in chapter
4.4.5.2 of the NOx Technical Code should be
common to those engines.
With regard to the allowable adjustments within
an engine group the manufacturer is to provide
documentary evidence and/or historical data (e.g.
previous test reports) to substantiate that the range
of adjustments which are included in the Technical
File will permit the engine to operate within the
emissions limits as set down in MARPOL Annex
VI Regulation 13(3)(a) and chapter 3 of the NOx
Technical Code.
Some manufacturers have termed such tests
Parameter Sensitivity tests.
It will be up to the attending surveyor, at the time
of the Parent Engine emission test to confirm that
the allowable adjustments do not result in the total
weighted average NOx emission value of that
engine exceeding the permissible limits.
In selecting the Parent Engine for a group the most
adverse features affecting the NOx emission level
should be incorporated. In general the Parent
Engine should have the highest NOx emission
level of any of the proposed configurations defined
by the manufacturer as the engine Group.
8.2 On Parent Engine selection for a
Family.
4.3.3 The selection procedure for the parent engine is
such that the selected engine incorporates those features
which will most adversely affect the NOx emission level.
This engine, in general, shall have the highest NOx
emission level among all of the engines in the family.
For the engine family concept the Parent Engine
must be selected based on criteria contained in
chapter 4.3.9.2 of the NOx Technical Code
The parent engine must have the highest NOx
emission value (as a weighted average in terms of
g/kWh).
8.3 On the selection of a Parent Engine
for an Engine Group.
4.4.7 The selection of the Parent engine shall be in
accordance with the criteria in 4.3.9 (Guidelines for
Selecting the Parent Engine of an Engine Family), as
applicable. It is not always possible to select a parent
engine from small volume production engines in the
same way as the mass produced engines (engine family).
The first engine ordered may be registered as the parent
engine. The method used to select the parent engine to
represent the engine group shall be agreed to and
approved by the Administration.
For the engine group concept the Parent Engine
must be tested with the allowable adjustments set
to those positions documented in the Technical File
which give the worst NOx emission limits.
Emissions of Nitrogen Oxides (NOx) from Marine Diesel
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The engine’s actual NOx emission value is the
value obtained at the time of the test bed test of the
Parent Engine with the engine adjusted, within the
allowable parameters as documented in the
Technical File, to give the worst case (highest) NOx
emissions. This will ensure that the Parent Engine
and all members of the group (or family) always
operate at or below this worst case scenario and
therefore are always in compliance with the Annex
VI Regulation 13 limits.
8.4 On the Parent Engine selection for a
family.
4.4.5 The Administration shall review for certification
approval the selection of the parent engine within the
family and shall have the option of selecting a different
engine, either for approval or production conformity
testing, in order to have confidence that the complete
family of engines complies with the NOx emission
limits.
Where an Administration selects a different engine
from that proposed by the engine builder then the
engine builder could elect to test both but could
proceed on the basis of testing only the engine as
selected by the Administration.
8.5 On the Family concept and
Conformity of Production.
4.3.7 Before granting an engine family approval, the
Administration shall take the necessary measures to
verify that adequate arrangements have been made to
ensure effective control of the conformity of production.
The extension of the engine family approval to
other sites (whether or not part of the parent
engine builder company) is dependant on where
control lies which ensures conformity of
production. Where another site is responsible for
its own conformity of production that builder
cannot be covered by the original parent engine
certification.
What is the definition of the word ‘adequate’ (here
and in subsequent references to the conformity of
production)? The existence of an ISO 9000 Quality
Assurance scheme does not automatically satisfy
the Conformity of Production (COP) control
procedure requirements (section 6).
8.6 Do tests which are used to produce
data on which to base the Parent Engine
selection have to be carried out under
survey conditions?
4.3.4 On the basis of tests and engineering judgement,
the manufacturer shall propose which engines belong to
an engine family, which engine(s) produce the highest
NOx emissions, and which engine(s) should be selected
for certification testing
Tests which are used to produce data on which to
base the Parent Engine selection do not need to be
carried out under survey conditions. However
those tests do need to be carried out in accordance
with the NOx Technical Code procedures.
Sufficient data must be submitted in order that the
results of such in-house testing can be verified as
part of the approval process.