EN ISO 3675:1998
(Main)Crude petroleum and liquid petroleum products - Laboratory determination of density - Hydrometer method (ISO 3675:1998)
Crude petroleum and liquid petroleum products - Laboratory determination of density - Hydrometer method (ISO 3675:1998)
Migrated from Progress Sheet (TC Comment) (2000-07-10): Revision of EN ISO 3675:1995
Rohöl und flüssige Mineralölerzeugnisse - Bestimmung der Dichte oder der relativen Dichte im Labor-Aräometerverfahren (ISO 3675:1993)
Pétroles bruts et produits pétroliers liquides - Détermination en laboratoire de la masse volumique ou de la densité relative - Méthode à l'aréomètre (ISO 3675:1993)
Surova nafta in tekoči naftni proizvodi - Laboratorijsko določevanje gostote ali relativne gostote z areometrom (ISO 3675:1998)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-1999
1DGRPHãþD
SIST EN ISO 3675:1998
6XURYDQDIWDLQWHNRþLQDIWQLSURL]YRGL/DERUDWRULMVNRGRORþHYDQMHJRVWRWHDOL
UHODWLYQHJRVWRWH]DUHRPHWURP ,62
Crude petroleum and liquid petroleum products - Laboratory determination of density -
Hydrometer method (ISO 3675:1998)
Rohöl und flüssige Mineralölerzeugnisse - Bestimmung der Dichte oder der relativen
Dichte im Labor-Aräometerverfahren (ISO 3675:1993)
Pétroles bruts et produits pétroliers liquides - Détermination en laboratoire de la masse
volumique ou de la densité relative - Méthode a l'aréometre (ISO 3675:1993)
Ta slovenski standard je istoveten z: EN ISO 3675:1998
ICS:
75.040 Surova nafta Crude petroleum
75.080 Naftni proizvodi na splošno Petroleum products in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 3675
Third edition
1998-06-15
Crude petroleum and liquid petroleum
products — Laboratory determination of
density — Hydrometer method
Pétrole brut et produits pétroliers liquides — Détermination en laboratoire
de la masse volumique — Méthode à l'aréomètre
A
Reference number
ISO 3675:1998(E)
ISO 3675:1998(E)
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.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 3675 was prepared by Technical Committee
ISO/TC 28, Petroleum products and lubricants, subcommittee SC 3, Static
petroleum measurement.
This third edition cancels and replaces the second edition (ISO 3675:1993),
of which it constitutes a Technical revision.
Annex A forms an integral part of this International Standard. Annex B is for
information only.
© ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
©
INTERNATIONAL STANDARD ISO ISO 3675:1998(E)
Crude petroleum and liquid petroleum products —
Laboratory determination of density — Hydrometer method
WARNING — The use of this International Standard may involve hazardous materials, operations and
equipment. This International Standard does not purport to address all of the safety problems associated
with its use. It is the responsibility of the user of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies a method for the laboratory determination, using a glass hydrometer, of
the density at 15 °C of crude petroleum, liquid petroleum products, and mixtures of petroleum and non-
petroleum products normally handled as liquids and having a Reid vapour pressure (RVP) of 100 kPa or less.
This International Standard is suitable for determining the density of mobile transparent liquids. It can also be
used for viscous liquids by carrying out the determinations at temperatures above ambient using a suitable
liquid bath for temperature control. It can also be used for opaque liquids by reading the hydrometer scale
where the top of the meniscus meets the stem of the hydrometer and applying a correction from table 1
(see 11.2).
Since hydrometers are calibrated to read correctly at the specified temperature, scale readings made at other
temperatures are only hydrometer readings and not values of density at these other temperatures.
NOTES
1 The accuracy of the density, determined by the procedures given in this International Standard, for volatile and/or waxy
crude oils containing free and/or suspended water and sediments can be less than inferred from the precision data quoted
in clause 13. This is due to the possible loss of light components during sample mixing. However, sample mixing is
necessary to ensure that the test portion transferred to the hydrometer cylinder is as representative as possible of the bulk
sample. Techniques are given in clause 7 which are designed to minimize such loss of light component.
2 Values of density at 15 °C can be converted using standard measurement tables to equivalent values of API gravity or
relative density so that measurements may be made in the units of local convenience.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute
provisions of this International Standard. For dated references, subsequent amendments to, or revisions of,
any of these publications do not apply. However, parties to agreements based on this International Standard
are encouraged to investigate the possibility of applying the most recent editions of the normative documents
indicated below. For undated references, the latest edition of the normative document referred to applies.
Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 91-1:1992, Petroleum measurement tables — Part 1: Tables based on reference temperatures of 15 °C and
60 °F.
ISO 649-1:1981, Laboratory glassware — Density hydrometers for general purposes — Part 1: Specification.
©
ISO
ISO 3675:1998(E)
ISO 3170:1988, Petroleum liquids — Manual sampling.
ISO 3171:1988, Petroleum liquids — Automatic pipeline sampling.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1
density
mass per unit volume expressed in either kilograms per cubic metre or grams per millilitre at 15 °C and
101,325 kPa
3.2
cloud point
temperature at which a cloud of wax crystals first appears in a liquid when it is cooled under specified
conditions
3.3
wax appearance temperature
WAT
temperature at which waxy solids form when petroleum or petroleum products are cooled under specified
conditions
3.4
pour point
lowest temperature at which a sample of petroleum or petroleum product will continue to flow when it is
cooled under specified conditions
4 Principle
The sample is brought to a specified temperature and a test portion transferred to a hydrometer cylinder that
has been brought to approximately the same temperature. The appropriate hydrometer, whose temperature
has also been regulated, is lowered into the test portion and allowed to settle. After temperature equilibrium
has been reached, the hydrometer scale is read, the temperature of the test portion taken and the observed
hydrometer reading reduced to 15 °C using standard measurement tables. If necessary, the hydrometer
cylinder and its contents are placed in a constant temperature bath to avoid excessive temperature variation
during the test.
5 Apparatus
5.1 Hydrometer cylinder, of clear glass, plastics material, or metal, with an inside diameter at least 25 mm
greater than the outside diameter of the hydrometer (5.2) and a height such that the hydrometer floats in the
test portion with at least 25 mm clearance between the bottom of the hydrometer and the bottom of the
cylinder.
Plastics material used for the construction of hydrometer cylinders shall be resistant to discolouration or attack
and shall not affect the properties of the material being tested. In addition, they shall not become opaque
under prolonged exposure to light.
NOTE — For convenience in pouring, the hydrometer cylinder may have a lip on the rim.
5.2 Hydrometers, of glass, graduated in units of density, conforming to ISO 649-1 and the requirements given
in table 1. (See also annex A.)
©
ISO
ISO 3675:1998(E)
Table 1 — Requirements for hydrometers
Unit Density range Each Scale interval Maximum Meniscus
unit scale error correction
kg/m 600 to 1100 20 0,2 ± 0,2 + 0,3
at 15 °C 600 to 1100 50 0,5 ± 0,3 + 0,7
600 to 1100 50 1,0 ± 0,6 + 1,4
g/ml 0,600 to 1,100 0,02 0,000 2 ± 0,000 2 + 0,000 3
at 15 °C 0,600 to 1,100 0,05 0,000 5 ± 0,000 3 + 0,000 7
0,600 to 1,100 0,05 0,001 0 ± 0,000 6 + 0,001 4
5.3 Constant temperature bath, if required, of dimensions such that it can accommodate the hydrometer
cylinder with the test portion fully immersed below the surface of the bath liquid and a temperature control
system capable of maintaining the bath at the test temperature ± 0,25 °C, throughout the duration of the test.
5.4 Thermometer, having a range, graduation intervals and maximum permitted scale error as shown in
table 2.
Table 2 — Requirements for thermometers
Range Graduation interval Maximum scale error
°C
0,1 ± 0,1
- 1 to 38
0,2 ± 0,15
- 20 to 102
NOTES
1 Thermometers IP 39C and IP 64C/ASTM 12C are suitable.
2 Resistance thermometers may be used, provided that the total uncertainty of the calibrated system is not greater than
the uncertainty when using liquid-in-glass thermometers.
5.5 Glass or plastics stirring rod, optional, approximately 450 mm in length.
6 Sampling
Samples shall be taken in accordance with ISO 3170, ISO 3171, or an equivalent National Standard.
NOTE — When sampling volatile liquids using an automatic sampling technique, unless a sample receiver of variable
volume is used to collect the sample and transport it to the laboratory, loss of light components may occur which will
affect the accuracy of the density measurement.
7 Sample preparation
7.1 Sample mixing
The portion of the sample tested shall be as representative as possible of the bulk sample, and sample mixing
may be necessary. However, precautions shall be taken to maintain the integrity of the sample during this
operation.
©
ISO
ISO 3675:1998(E)
The mixing of volatile crude oils and petroleum products containing sediments and/or water, or the heating of
waxy volatile crude oils or petroleum products may result in the loss of light components. Guidance as to how
to treat the different materials and to minimize such light component loss is given in 7.1.1 to 7.1.4.
7.1.1 Volatile crude oils and petroleum products having a RVP greater than 50 kPa
Mix the sample wherever possible in the original container, and in a closed system in order to minimize the
loss of light components.
NOTE — Mixing volatile samples in open containers will lead to loss of light components and will affect the value of the
density obtained.
7.1.2 Waxy crude oils
If the crude oil has a pour point above 10 °C, or a cloud point or WAT (3.3) above 15 °C, warm the sample to
9 °C above its pour point, or 3 °C above its cloud point or WAT, prior to mixing. Mix the sample wherever
possible in the original container, and in a closed system in order to minimize the loss of light components.
7.1.3 Waxy distillates
Warm the sample to 3 °C above its cloud point or WAT prior to mixing.
7.1.4 Residual fuel oils
Heat the sample to the test temperature prior to mixing (see 7.2.1 and note 2 in 7.2.1).
7.2 Test temperature
7.2.1 Bring the sample to the test temperature which shall be such that the sample is sufficiently fluid, but not
so high as to cause loss of light components, nor so low as to result in the presence of wax in the test sample.
NOTES
1 The density determined by the hydrometer method is most accurate at or near the reference temperature of 15 °C.
2 The hydrometer reading is obtained at a temperature appropriate to the physio-chemical characteristics of the material
being tested. This temperature is preferably close to the reference temperature of 15 °C or, when the density is used in
conjunction with bulk oil measurements, close to – 3 °C, or at the bulk oil temperature, to minimize errors due to volume
correction.
7.2.2 For crude oil, bring the sample to 15 °C, or 9 °C above its pour point, or 3 °C above its cloud point or wax
appearance temperature, whichever is the higher.
NOTE — For crude oil, an indication of the wax appearance temperature can be found using IP 389 (see [4] in annex B)
with the modification of using 50 μl ± 0,5 μl of sample. The precision for determining WAT of crude oils using IP 389 has
not been determined.
8 Verification of apparatus
8.1 Hydrometers shall be regularly verified by comparison with a reference hydrometer traceable to a
National Standard or a traceable density certified reference material (CRM), and where necessary recalibrated
at least every five years.
8.2 Thermometers shall be regularly verified by comparison with a reference thermometer traceable to a
National Standard.
©
ISO
ISO 3675:1998(E)
9 Preparation of apparatus
9.1 Check that the hydrometer scale is correctly located within the hydrometer stem by reference to the
datum mark. If the scale has moved, reject the hydrometer.
9.2 Bring the hydrometer cylinder and hydrometer to approximately the sample temperature (see 7.2.1 and
note 2 in 7.2.1).
10 Procedure
10.1 Transfer a portion of the sample at test temperature (see 7.2.1 and note 2 in 7.2.1) to the clean
hydrometer cylinder (5.1) at a stabilized temperature, without splashing, avoiding the entrainment of air
bubbles, and reducing to a minimum the evaporation of the lower boiling constituents of volatile materials.
10.2 Remove any bubbles that have collected on the surface of the sample, by touching them with a piece of
clean filter paper.
10.3 Place the cylinder containing the sample in a vertical position in a location free from air currents and
where the te
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