ISO 19970:2025
(Main)Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels — Metering of gas as fuel on LNG carriers during cargo transfer operations
Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels — Metering of gas as fuel on LNG carriers during cargo transfer operations
This document specifies the minimum requirements to quantify boil-off gas (BOG) consumed on liquefied natural gas (LNG) carriers for their own functions, in particular for power generation and during cargo transfer operations. This document provides requirements for the metering of BOG and the subsequent calorific value calculations, which can be taken into account when the energy transferred during cargo transfer is determined. This document also gives performance requirements and calibration of the elements included in the BOG measurement system. This document, with some modifications, can also be applied to the measurement of BOG consumed by LNG carriers at sea.
Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à base non pétrolière — Mesurage du gaz comme carburant sur les transporteurs de GNL pendant les opérations de transfert de cargaison
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Buy Standard
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International
Standard
ISO 19970
Second edition
Refrigerated hydrocarbon and non-
2025-07
petroleum based liquefied gaseous
fuels — Metering of gas as fuel on
LNG carriers during cargo transfer
operations
Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à
base non pétrolière — Mesurage du gaz comme carburant sur
les transporteurs de GNL pendant les opérations de transfert de
cargaison
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design requirements . 3
4.1 General .3
4.2 BOG measurement system .3
4.2.1 General .3
4.2.2 Flowmeter .4
4.2.3 Associated measuring instruments .4
4.2.4 Flow computer . .4
4.2.5 Indicating device .4
5 Uncertainty requirement . 4
6 Calibration and uncertainty verification . 5
6.1 General .5
6.2 Calibration at laboratory or factory before installation .5
6.3 Calibration and verification after installation .5
6.4 Periodic uncertainty verification of BOG measurement system .5
7 Metering and calculation . 6
7.1 General .6
7.2 Metering .6
7.3 Calculation of heating value . .6
Annex A (informative) Typical installation of fuel gas flowmeters . 7
Annex B (informative) Calculation of energy transferred . 8
Annex C (informative) Uncertainty calculation examples . 9
Bibliography .13
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
lubricants from natural or synthetic sources, Subcommittee SC 5, Measurement of refrigerated hydrocarbon
and non-petroleum based liquefied gaseous fuels.
This second edition cancels and replaces the first edition (ISO 19970:2017), which has been technically
revised.
The main changes are as follows:
— boil-off gas (BOG) measurement system has been defined;
— uncertainty calculation examples have been added to Annex C.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
[14]
Concerns over the emission of pollutants from ship exhausts prompted IMO to enact MARPOL Annex VI
to the IMO Protocol of 1997, which sets limits on sulfur oxide (SOx) and nitrogen oxide (NOx) emissions.
MARPOL Annex VI also specifies a global cap which limits the permitted sulfur content of fuel oil to a mass
fraction of 3,5 % and special SOx emission control areas (SECAs) where the sulfur contents must not exceed a
mass fraction of 1,0 %. In order to comply with these requirements, ships generally require special facilities
to be installed to limit SOx emissions, unless they use low sulfur fuel oil.
Liquefied natural gas (LNG) carriers are capable of utilizing boil-off gas (BOG) in ships and shore tanks.
They return gas during the cargo transfer operation as fuel for their own power generation, if commercial
value of such energy consumed on board is accountable as an element of custody transfer measurement. This
document provides the procedures for metering gas and assessing its calorific value, and the requirements
for metering devices.
Aspects of safety are not dealt with in this document. It is the responsibility of the user to ensure that the
system meets applicable safety regulations.
v
International Standard ISO 19970:2025(en)
Refrigerated hydrocarbon and non-petroleum based liquefied
gaseous fuels — Metering of gas as fuel on LNG carriers
during cargo transfer operations
1 Scope
This document specifies the minimum requirements to quantify boil-off gas (BOG) consumed on liquefied
natural gas (LNG) carriers for their own functions, in particular for power generation and during cargo
transfer operations.
This document provides requirements for the metering of BOG and the subsequent calorific value
calculations, which can be taken into account when the energy transferred during cargo transfer is
determined. This document also gives performance requirements and calibration of the elements included
in the BOG measurement system.
This document, with some modifications, can also be applied to the measurement of BOG consumed by LNG
carriers at sea.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
boil off
process of evaporation of a liquid resulting from heat ingress or a drop in pressure
[SOURCE: ISO 10976:2023, 3.1.6]
3.2
boil-off gas
BOG
vapour (3.11) produced by boil off (3.1)
Note 1 to entry: BOG in this document refers to the low molecular gas returned from shore tanks to ship tanks and the
gas produced in ship cargo tanks during cargo transfer operation.
[SOURCE: ISO 10976:2023, 3.1.7 — Note 1 to entry has been added.]
3.3
custody transfer measurement
measuring of liquid level, liquid and vapour temperature, vapour pressure and analysis of the composition of
liquid natural gas to be delivered to or from a tank, by which volumetric and other data are determined as a
basis of payment of cost or assessment of duty
3.4
custody transfer measurement system
CTMS
structure that processes inputs from level gauges, thermometers, pressure gauges, etc., and provides
custody transfer measurement information on board, generating documents with regard to custody transfer
of liquid natural gas
[SOURCE: ISO 18132-1:2011, 2.1.4, modified]
3.5
flowmeter
flow measuring device which indicates the measured flowrate
3.6
gas dangerous space
gas dangerous zone
area which consists of the following places:
— a space in the cargo area which is not arranged or equipped in an approved manner to ensure that its
atmosphere is at all times maintained in a gas-safe condition;
— an enclosed space outside the cargo area through which any piping containing liquid or gaseous products
passes, or within which such piping terminates, unless approved arrangements are installed to prevent
any escape of product vapour into the atmosphere of that space;
— a cargo containment system and cargo piping;
— a hold space where cargo is carried in a cargo containment system requiring a secondary barrier;
— a hold space where cargo is carried in a cargo containment system not requiring a secondary barrier;
— a space separated from a hold space describe
...
International
Standard
ISO 19970
Second edition
Refrigerated hydrocarbon and non-
petroleum based liquefied gaseous
fuels — Metering of gas as fuel on
LNG carriers during cargo transfer
operations
Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à
base non pétrolière — Mesurage du gaz comme carburant sur
les transporteurs de GNL pendant les opérations de transfert de
cargaison
PROOF/ÉPREUVE
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
PROOF/ÉPREUVE
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design requirements . 3
4.1 General .3
4.2 BOG measurement system .3
4.2.1 General .3
4.2.2 Flowmeter .4
4.2.3 Associated measuring instruments .4
4.2.4 Flow computer . .4
4.2.5 Indicating device .4
5 Uncertainty requirement . 4
6 Calibration and uncertainty verification . 5
6.1 General .5
6.2 Calibration at laboratory or factory before installation .5
6.3 Calibration and verification after installation .5
6.4 Periodic uncertainty verification of BOG measurement system .5
7 Metering and calculation . 6
7.1 General .6
7.2 Metering .6
7.3 Calculation of heating value . .6
Annex A (informative) Typical installation of fuel gas flowmeters . 7
Annex B (informative) Calculation of energy transferred . 8
Annex C (informative) Uncertainty calculation examples . 9
Bibliography .13
PROOF/ÉPREUVE
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
lubricants from natural or synthetic sources, Subcommittee SC 5, Measurement of refrigerated hydrocarbon
and non-petroleum based liquefied gaseous fuels.
This second edition cancels and replaces the first edition (ISO 19970:2017), which has been technically
revised.
The main changes are as follows:
— boil-off gas (BOG) measurement system has been defined;
— uncertainty calculation examples have been added to Annex C.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
PROOF/ÉPREUVE
iv
Introduction
[14]
Concerns over the emission of pollutants from ship exhausts prompted IMO to enact MARPOL Annex VI
to the IMO Protocol of 1997, which sets limits on sulfur oxide (SOx) and nitrogen oxide (NOx) emissions.
MARPOL Annex VI also specifies a global cap which limits the permitted sulfur content of fuel oil to a mass
fraction of 3,5 % and special SOx emission control areas (SECAs) where the sulfur contents must not exceed a
mass fraction of 1,0 %. In order to comply with these requirements, ships generally require special facilities
to be installed to limit SOx emissions, unless they use low sulfur fuel oil.
Liquefied natural gas (LNG) carriers are capable of utilizing boil-off gas (BOG) in ships and shore tanks.
They return gas during the cargo transfer operation as fuel for their own power generation, if commercial
value of such energy consumed on board is accountable as an element of custody transfer measurement. This
document provides the procedures for metering gas and assessing its calorific value, and the requirements
for metering devices.
Aspects of safety are not dealt with in this document. It is the responsibility of the user to ensure that the
system meets applicable safety regulations.
PROOF/ÉPREUVE
v
International Standard ISO 19970:2025(en)
Refrigerated hydrocarbon and non-petroleum based liquefied
gaseous fuels — Metering of gas as fuel on LNG carriers
during cargo transfer operations
1 Scope
This document specifies the minimum requirements to quantify boil-off gas (BOG) consumed on liquefied
natural gas (LNG) carriers for their own functions, in particular for power generation and during cargo
transfer operations.
This document provides requirements for the metering of BOG and the subsequent calorific value
calculations, which can be taken into account when the energy transferred during cargo transfer is
determined. This document also gives performance requirements and calibration of the elements included
in the BOG measurement system.
This document, with some modifications, can also be applied to the measurement of BOG consumed by LNG
carriers at sea.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
boil off
process of evaporation of a liquid resulting from heat ingress or a drop in pressure
[SOURCE: ISO 10976:2023, 3.1.6]
3.2
boil-off gas
BOG
vapour (3.11) produced by boil off (3.1)
Note 1 to entry: BOG in this document refers to the low molecular gas returned from shore tanks to ship tanks and the
gas produced in ship cargo tanks during cargo transfer operation.
[SOURCE: ISO 10976:2023, 3.1.7 — Note 1 to entry has been added.]
PROOF/ÉPREUVE
3.3
custody transfer measurement
measuring of liquid level, liquid and vapour temperature, vapour pressure and analysis of the composition of
liquid natural gas to be delivered to or from a tank, by which volumetric and other data are determined as a
basis of payment of cost or assessment of duty
3.4
custody transfer measurement system
CTMS
structure that processes inputs from level gauges, thermometers, pressure gauges, etc., and provides
custody transfer measurement information on board, generating documents with regard to custody transfer
of liquid natural gas
[SOURCE: ISO 18132-1:2011, 2.1.4, modified]
3.5
flowmeter
flow measuring device which indicates the measured flowrate
3.6
gas dangerous space
gas dangerous zone
area which consists of the following places:
— a space in the cargo area which is not arranged or equipped in an approved manner to ensure that its
atmosphere is at all times maintained in a gas-safe condition;
— an enclosed space outside the cargo area through which any piping containing liquid or gaseous products
passes, or within which such piping terminates, unless approved arrangements are installed to prevent
any escape of product vapour into the atmosphere of that space;
— a cargo containment system and cargo piping;
— a hold space where cargo is carried in a cargo containment system requiring a secondary barrier;
— a hold space where cargo is carried in a cargo containment system not requiring a
...
ISO/PRF 19970
ISO/TC 28/SC 5
Secretariat: JISC
Date: 2025-05-07
Refrigerated hydrocarbon and non-petroleum based liquefied
gaseous fuels — Metering of gas as fuel on LNG carriers during cargo
transfer operations
Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à base non pétrolière — Mesurage du gaz comme
carburant sur les transporteurs de GNL pendant les opérations de transfert de cargaison
PROOF
ISO/DIS PRF 19970.2:2025(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
E-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2024 – All rights reserved
ii
ISO/FDISPRF 19970:20242025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design requirements . 3
4.1 General . 3
4.2 BOG measurement system . 4
5 Uncertainty requirement . 5
6 Calibration and uncertainty verification . 5
6.1 General . 5
6.2 Calibration at laboratory or factory before installation . 6
6.3 Calibration and verification after installation . 6
6.4 Periodic uncertainty verification of BOG measurement system . 6
7 Metering and calculation . 6
7.1 General . 6
7.2 Metering . 7
7.3 Calculation of heating value . 7
Annex A (informative) Typical installation of fuel gas flowmeters . 8
Annex B (informative) Calculation of energy transferred . 10
Annex C (informative) Uncertainty calculation examples . 11
Bibliography . 16
iii
ISO/DIS PRF 19970.2:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
lubricants from natural or synthetic sources, Subcommittee SC 5, Measurement of refrigerated hydrocarbon and
non-petroleum based liquefied gaseous fuels.
This second edition cancels and replaces the first edition (ISO 19970:2017), which has been technically
revised.
The main changes are as follows:
— boil-off gas (BOG) measurement system has been defined;
— uncertainty calculation examples have been added to Annex C.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv © ISO 2024 – All rights reserved
iv
ISO/FDISPRF 19970:20242025(en)
Introduction
Concerns over the emission of pollutants from ship exhausts prompted IMO to enact MARPOL Annex
[14] [ ]
VI VI 0 to the IMO Protocol of 1997, which sets limits on sulfur oxide (SOx) and nitrogen oxide (NOx)
emissions. MARPOL Annex VI also specifies a global cap which limits the permitted sulfur content of fuel oil
to a mass fraction of 3,5 % and special SOx emission control areas (SECAs) where the sulfur contents must not
exceed a mass fraction of 1,0 %. In order to comply with these requirements, ships generally require special
facilities to be installed to limit SOx emissions, unless they use low sulfur fuel oil.
Liquefied natural gas (LNG) carriers are capable of utilizing boil-off gas (BOG) in ships and shore tanks. They
return gas during the cargo transfer operation as fuel for their own power generation, if commercial value of
such energy consumed on board is accountable as an element of custody transfer measurement. This
document provides the procedures for metering gas and assessing its calorific value, and the requirements for
metering devices.
Aspects of safety are not dealt with in this document. It is the responsibility of the user to ensure that the
system meets applicable safety regulations.
v
DRAFT International Standard ISO/FDIS 19970:2024(en)
Refrigerated hydrocarbon and non-petroleum based liquefied
gaseous fuels – — Metering of gas as fuel on LNG carriers during cargo
transfer operations
1 Scope
This document specifies the minimum requirements to quantify boil-off gas (BOG) consumed on liquefied
natural gas (LNG) carriers for their own functions, in particular for power generation and during cargo
transfer operations.
This document provides requirements for the metering of BOG and the subsequent calorific value calculations,
which can be taken into account when the energy transferred during cargo transfer is determined. This
document also gives performance requirements and calibration of the elements included in the BOG
measurement system.
This document, with some modifications, can also be applied to the measurement of BOG consumed by LNG
carriers at sea.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 98--3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
boil off
process of evaporation of a liquid resulting from heat ingress or a drop in pressure
[SOURCE: ISO 10976:2023, 3.1.6]
3.2
boil-off gas
BOG
vapour (3.14)(3.11) produced by boil off (3.1)
ISO/DIS PRF 19970.2:2025(en)
Note 1 to entry: BOG in this document refers to the low molecular gas returned from shore tanks to ship tanks and the
gas produced in ship cargo tanks during cargo transfer operation.
[SOURCE: ISO 10976:2023, 3.1.7 — Note 1 to entry has been added.]
3.3 3.4
custody transfer measurement
measuring of liquid level, liquid and vapour temperature, vapour pressure and analysis of the composition of
liquid natural gas to be delivered to or from a tank, by which volumetric and other data are determined as a
basis of payment of cost or assessment of duty
3.4 3.5
custody transfer measurement system
CTMS
structure that processes inputs from level gauges, thermometers, pressure gauges, etc., and provides custody
transfer measurement information on board, generating documents with regard to custody transfer of liquid
natural gas
[SOURCE: ISO 18132-‑1:2011, 2.1.4, modified]
3.5 3.6
flowmeter
flow measuring device which indicates the measured flowrate
3.6 3.7
gas dangerous space
gas dangerous zone
area which consists of the following places:
— — a space in the cargo area which is not arranged or equipped in an approved manner to ensure that its
atmosphere is at all times maintained in a gas-safe condition;
— — an enclosed space outside the cargo area through which any piping containing liquid or gaseous
products passes, or within which such piping terminates, unless approved arrangements are installed to
prevent any escape of product vapour into the atmosphere of that space;
— — a cargo containment system and cargo piping;
— — a hold space where cargo is carried in a cargo containment system requiring a secondary barrier;
— — a hold space where cargo is carried in a cargo containment system not requiring a secondary barrier;
— — a space separated from a hold space described in 4.1 above[of the International Code for the
Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code)] by a Gasgas-tight steel
boundary;
— — a cargo pump room and cargo compressor room;
— — a zone on the open deck, or semi-enclosed space on the open deck, within 3 m of any cargo tank outlet,
gas or vapour outlet, cargo pipe flange or cargo valve or of entrances and ventilation openings to cargo
pump rooms and cargo compressor rooms;
2 © ISO 2023 – All rights reserved
ISO/FDISPRF 19970:20242025(en)
— — the open deck over the cargo area and 3 m forward and aft of the cargo area on the open deck up to a
height of 2.4m,4 m above the weather deck;
— — a zone within 2.4m,4 m of the outer surface of a cargo containment system where such surface is
exposed to the weather;
— — an enclosed or semi-enclosed space in which pipes containing products are located. A space which
contains gas detection equipment complying with 13.6.5 (of the IGC code) and a space utilizing boil-off gas
as fuel and complying with Chapter 16 are not considered gas-dangerous spaces in this context;
— — a compartment for cargo hoses;
— — an enclosed or semi-enclosed space having a direct opening into any gas-dangerous space or zone.
Note 1 to entry: This is defined by the International Code for the Construction and Equipment of Ships Carrying
[12] [ ]
Liquefied Gases in Bulk (IGC Code) ). 0
3.7 3.9
inherent error
difference of a measuring device when it is tested against a reference standard under controlled conditions as
specified by the manufacturer
3.8 3.10
LNG carrier
cargo ship specifically constructed and used for the carriage of liquid natural gas in bulk
3.9 3.11
maximum permissible error
extreme value of measurement error, with re
...
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