ISO/TR 9464:2008

TECHNICAL ISO/TR
REPORT 9464
Second edition
2008-05-15
Guidelines for the use of ISO 5167:2003
Lignes directrices pour l'utilisation de l'ISO 5167:2003

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 How the structure of this guide relates to ISO 5167:2003 (all parts). 2
5 Guidance on the use of ISO 5157:2003 (all parts) . 2
5.1 Guidance specific to the use of ISO 5167-1:2003. 2
5.2 Guidance specific to the use of ISO 5167-2:2003. 8
5.3 Guidance specific to the use of ISO 5167-3:2003. 23
5.4 Guidance specific to the use of ISO 5167-4:2003. 24
6 Information of a general nature relevant to the application of ISO 5167:2003 (all parts). 25
6.1 Secondary instrumentation . 25
6.2 Measurement of pressure and differential pressure. 27
6.3 Measurement of temperature . 31
6.4 Determination of density. 35
6.5 Electrical supply and electrical installations . 40
Annex A (informative) Principles of measurement and computation. 41
Annex B (informative) Computation of compressibility factor for natural gases. 57
Annex C (informative) Orifice plate assembly. 59
Bibliography . 68

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 9464 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits,
Subcommittee SC 2, Pressure differential devices.
This second edition cancels and replaces the first edition (ISO/TR 9464:1998), which has been technically
revised.
iv © ISO 2008 – All rights reserved

Introduction
The objective of this Technical Report is to assist users of ISO 5167, which was published in 2003 in four
parts. Guidance on particular clauses of ISO 5157:2003 is given.
Some clauses of ISO 5167:2003 (parts 1 to 4) are not commented upon and the corresponding clause
numbers are therefore omitted from this Technical Report, except when it has been thought to be useful to
keep a continuous numbering of paragraphs.

TECHNICAL REPORT ISO/TR 9464:2008(E)

Guidelines for the use of ISO 5167:2003
1 Scope
The objective of this Technical Report is to provide guidance on the use of ISO 5167:2003 (all parts).
ISO 5167:2003 is an International Standard for flow measurement based on the differential pressure
generated by a constriction introduced into a circular conduit (see ISO 5167-1:2003, 5.1). It presents a set of
rules and requirements based on theory and experimental work undertaken in the field of flow measurement.
For a more detailed description of the scope, reference should be made to ISO 5167-1:2003, Clause 1.
Definitions and symbols applicable to this Technical Report are given in ISO 5167-1:2003, Clauses 3 and 4.
Neither ISO 5167-1:2003 nor this Technical Report give detailed theoretical background, for which reference
should be made to any general textbook on fluid flow.
With the application of the rules and requirements set out in ISO 5167-1:2003, it is practicable to achieve flow
measurement within an uncertainty of approximately 1 % of the calculated flowrate. The constraints applicable
to each of the primary devices described in ISO 5167:2003 (parts 2 to 4) need to be given consideration
before determining the most suitable type for a particular application. Parts 2 to 4 can also be used to form the
basis for preliminary design of a metering system.
The information necessary for detailed design, manufacture and final check is specified in the clauses and
paragraphs of ISO 5167:2003 (parts 2 to 4).
Secondary instrumentation is not covered by ISO 5167-1:2003, but Clause 6 of this Technical Report makes
normative reference to ISO 2186.
2 Normative references
The following referenced documents are indispensable for the application 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 2186, Fluid flow in closed conduits — Connections for pressure signal transmissions between primary
and secondary elements
ISO/TR 3313:1998, Measurement of fluid flow in closed conduits — Guidelines on the effects of flow
pulsations on flow-measurement instruments
ISO 4006, Measurement of fluid flow in closed conduits — Vocabulary and symbols
ISO 5167-1:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 1: General principles and requirements
ISO 5167-2:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 2: Orifice plates
ISO 5167-3:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 3: Nozzles and Venturi nozzles
ISO 5167-4:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 4: Venturi tubes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4006 apply.
4 How the structure of this guide relates to ISO 5167:2003 (all parts)
Clause 5 of this Technical Report sets out the guidance specific to each of the four parts of ISO 5167:2003:
⎯ 5.1 covers part 1;
⎯ 5.2 covers part 2;
⎯ 5.3 covers part 3;
⎯ 5.4 covers part 4.
Subsequent subclause numbering relates to the clauses in each of the parts. Hence, 5.1.1 covers Clause 1 in
part 1; 5.4.3.1.1 covers Subclause 3.1.1 in part 4.
Guidance applicable to all four parts is given in Clause 6.
5 Guidance on the use of ISO 5157:2003 (all parts)
5.1 Guidance specific to the use of ISO 5167-1:2003
5.1.1 Scope
No comments on this clause.
5.1.2 Normative references
No comments on this clause.
5.1.3 Terms and definitions
No comments on this clause.
5.1.4 Symbols and subscripts
No comments on this clause.
5.1.5 Principle of the method of measurement and computation
5.1.5.1 Principle of the method of measurement
No comments on this subclause.
2 © ISO 2008 – All rights reserved

5.1.5.2 Method of determination of the diameter ratio of the standard primary device
See Annex A of this Technical Report.
5.1.5.3 Computation of flowrate
The equations to be used to determine the flowrate of a measuring system are given in ISO 5167-1:2003,
Clause 5. Some results of these calculations will be fixed with installation dimensions and will only need to be
computed once. Other calculations will need to be repeated for every flow measurement point. Annex A gives
worked examples of the iterative computations shown in ISO 5167-1:2003, Annex A.
5.1.5.4 Determination of density, pressure and temperature
5.1.5.4.1 General
No comments on this subclause.
5.1.5.4.2 Density
For details on density measurement, see 6.4.
For details on density computation, see Annex B of this Technical Report.
5.1.5.4.3 Static pressure
No comments on this subclause.
5.1.5.4.4 Temperature
The computation of temperature decrease resulting from expansion of the fluid through the primary device
requires knowledge of the Joule-Thomson coefficient. The coefficient is a function of temperature, pressure
and gas composition. The calculation can be carried out using an equation of state (see, in Annex B, the
“detailed method” using molar composition analysis) or by the use of an approximation valid for natural gas
mixtures that are not too rich, and when p and T are in the range given below. In the last case, the coefficient
is a function of p and T alone.
Provided that, in the molar composition of the natural gas, methane is greater than 80 %, the temperature is in
the range 0 °C to 100 °C and the absolute static pressure is in the range 100 kPa to 20 MPa (1 bar to 200 bar).
µ=−0,35 0,001 42t
JT
(1)
+−0,231 0,002 94tt+ 0,000 0136 0,998+ 0,000 41p− 0,000 111 5p+ 0,000 000 3p
()( )
where
µ is the Joule-Thomson coefficient, in kelvin per bar (K/bar);
JT
t is the temperature of the fluid, in degrees Celsius (°C);
p is the absolute static pressure of the fluid, in bar.
The uncertainty was determined from the differences between this equation and the Joule-Thomson
coefficient of 14 common natural gases and is given by
⎛⎞t
U=−0,066 1 for pu70bar (7 MPa) (2)
⎜⎟
⎝⎠
and
⎡⎤
⎛⎞tt(290− )⎛⎞1 1
U=−0,066 1 1− − for p> 70 bar (7 MPa) (3)
⎢⎥
⎜⎟ ⎜⎟
200 4 70 p
⎝⎠⎢⎥
⎝⎠
⎣⎦
where U is the (expanded) uncertainty in the Joule-Thomson coefficient (K/bar).
NOTE If an orifice plate with β = 0,6 has a differential pressure ∆p = 0,5 bar, the uncertainty in the Joule-Thomson
coefficient corresponds to an uncertainty in flowrate in the range from 0,001 % to 0,009 %, depending on the temperature,
the pressure and the gas composition.
5.1.6 General requirements for the measurements
5.1.6.1 Primary device
5.1.6.1.1 No comments on this subclause.
5.1.6.1.2 No comments on this subclause.
5.1.6.1.3 Table 1, whilst not exhaustive, lists materials most commonly used for the manufacture of primary
devices.
Table 1
...