SIST EN ISO 4257:1998

SLOVENSKI STANDARD
SIST EN ISO 4257:1998
01-maj-1998
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Liquefied petroleum gases - Method of sampling (ISO 4257:1988)
Flüssiggas - Probenahme (ISO 4257:1988)
Gaz de pétrole liquéfiés - Méthode d'échantillonnage (ISO 4257:1988)
Ta slovenski standard je istoveten z: EN ISO 4257:1995
ICS:
75.160.30 Plinska goriva Gaseous fuels
SIST EN ISO 4257:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 4257:1998

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SIST EN ISO 4257:1998

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SIST EN ISO 4257:1998

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SIST EN ISO 4257:1998

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SIST EN ISO 4257:1998

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SIST EN ISO 4257:1998
ISO
INTERNATIONAL STANDARD
4257
First edition
1988-12-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXAYHAPOflHAR OPrAHM3A~MFl fl0 CTAHfiAPTM3A~MM
Liquefied Petroleum gases - Method of sampling
Gaz de p&role liqu&fi& - M& thode d’bchan tillonnage
Reference number
ISO 4257 : 1988 (E)

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SIST EN ISO 4257:1998
ISO 4257 : 1988 (EI
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. Esch 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, govern-
mental 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.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 4257 was prepared by Technical Committee ISO/TC 28,
Petroleum products and lubrican ts.
0 International Organkation for Standardkation, 1988
Printed in Switzerland

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SIST EN ISO 4257:1998
ISO 4257 : 1988 (E)
INTERNATIONAL STANDARD
Liquefied Petroleum gases - Method of sampling
These consist predominantly of propane, propene, butanes and
1 Scope
butenes, with small proportions of ethane, ethene and/or pen-
tanes and pentenes. They are normally described in terms of
This International Standard specifies the procedure to be used
the predominant hydrocarbon, e.g. commercial butane or com-
for obtaining samples of non-refrigerated liquefied Petroleum
mercial propane.
gases (LPG) such as propane, butane or mixtures thereof. lt is
suitable for sampling into Containers to provide samples for
laboratory testing of products covered by ISO 9162.
4 Principle
Although this method tan be used to provide samples for com-
positional analysis by ISO 7941, it is strongly recommended
A liquid Sample is transferred from the Source into a Sample
that alternative apparatus, such as a variable-volume Container,
Container through a transfer line by purging the Container and
be used to minimize compositional changes that may occur.
filling it with liquid, then venting the Container to provide a
Development of an appropriate ISO method is under way.
20 % ullage so that 80 % of the liquid volume remains.
2 Normative references
5 Significance
The following Standards contain provisions which, through
Samples of liquefied Petroleum gases are examined by various
reference in this text, constitute provisions of this International
test methods to determine physical and Chemical
Standard. At the time of publication, the editions indicated
characteristics. The test results are often used for custody
were valid. All Standards are subject to revision, and Parties to
transfer and price determination. lt is therefore essential that
agreements based on this International Standard are encouraged
the samples be representative of the product to be tested.
to investigate the possibility of applying the most recent
editions of the Standards listed below. Members of IEC and ISO
maintain registers of currently valid International Standards.
6 General considerations for obtaining a
representative Sample
ISO 7941 : 1988, Commercial propane and butane - Analysis
by gas chromatography.
Great care is required to obtain a representative Sample,
- 1 ), Petroleum products - Fuels (class F) -
ISO 9162 :
especially if the material to be sampled is a mixture of gases.
Liquefied petroleum gases - Specifica tions.
The following factors shall be taken into account:
a) Take samples from the liquid Phase only.
3 Definition
b) Avoid sampling from the bottom of a vessel.
For the purposes of this International Standard, the following
definition applies.
c) Because of the wide variations in the construction of
liquefied petroleum gases (LPG): Petroleum gases which tanks for containing liquefied gases, it is difficult to specify a
tan be stored and/or handled in the liquid Phase under uniform method for obtaining representative samples of
moderate conditions of pressure and at ambient temperature. heterogeneous mixtures. With large bulk installations it may
1) To be published.
1

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SIST EN ISO 4257:1998
ISO 4257 : 1988 (El
homogeneity circulating the con- 7.3 Safety during transport
be possible to improve
bY
tents Prior to sampling
Precautions shall be taken to protect the integrity of the con-
tainer by packing the Container in a crate in accordance with
d) Directions for sampling cannot be explicit enough to
regulatory requirements and by using a protective cap on the
cover all cases. They need to be supplemented by judge-
valves so that accidental unseating of the valves or tampering
ment, skill and sampling experience. Extreme care and good
with them is avoided. lt is recommended that valves should
judgement are necessary to ensure that samples represen-
always be capped.
ting the general Character and average conditions are ob-
tained.
8 Apparatus
e) When sampling from pipelines under flow conditions,
the pressure in the line needs to be above vapour pressure
8.1 Sample Container
to avoid two-Phase conditions.
Use metal Sample Containers and fittings of a type which en-
sur
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