ISO/TR 11583:2012

TECHNICAL ISO/TR
REPORT 11583
First edition
2012-04-01
Measurement of wet gas flow by means
of pressure differential devices inserted
in circular cross-section conduits
Mesurage du débit de gaz humide au moyen d'appareils déprimogènes
insérés dans des conduites de section circulaire

Reference number
©
ISO 2012
©  ISO 2012
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ii © ISO 2012 – All rights reserved

Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 2
4  Symbols and subscripts . 2
5  Principle of the method of measurement and computation . 2
5.1  Principle of the method of measurement . 2
5.2  Computation . 4
6  Venturi tubes . 5
6.1  General . 5
6.2  Design requirements . 5
6.3  Pressure tappings . 5
6.4  Computation of gas flowrate . 6
6.5  Uncertainties . 8
7  Orifice plates . 9
7.1  General . 9
7.2  Design requirements . 9
7.3  Use of orifice plates with drain holes . 9
7.4  Pressure tappings . 9
7.5  Computation of gas flowrate . 10
7.6  Uncertainties . 12
8  Tracer techniques . 12
8.1  General . 12
8.2  Technique . 13
8.3  Measuring the gas flowrate using tracer techniques . 13
9  Comparison method . 14
10  Total mass flowrate known . 14
11  Using a throttling calorimeter . 15
12  Installation . 15
12.1  Flow conditioners . 15
12.2  Insulation . 15
12.3  Pressure tappings and impulse lines . 15
12.4  Gas composition . 16
12.5  Densitometers . 16
13  Sampling . 17
13.1  General . 17
13.2  Sampling points at the wet-gas meter . 17
13.3  Sampling points at test separators . 17
Annex A (informative) Calculations . 18
Bibliography . 25

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 11583 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed
conduits, Subcommittee SC 2, Pressure differential devices.
iv © ISO 2012 – All rights reserved

Introduction
ISO 5167-1:2003, ISO 5167-2:2003, and ISO 5167-4:2003 include specifications for Venturi tubes and orifice
plates, but are applicable only where the fluid can be considered as a single phase and the conduit is running
full.
If the fluid being measured is a wet gas there is an overreading which can be corrected using suitable wet-gas
correction equations.
TECHNICAL REPORT ISO/TR 11583:2012(E)

Measurement of wet gas flow by means of pressure differential
devices inserted in circular cross-section conduits
1 Scope
This Technical Report describes the measurement of wet gas with differential pressure meters. It applies to
two-phase flows of gas and liquid in which the flowing fluid mixture consists of gas in the region of 95 %
volume fraction or more (the exact limits on the mixture are defined in 6.4.3, 6.4.5, 7.5.3 and 7.5.5). This
Technical Report is an extension of ISO 5167. The ranges of gases and liquids from which the equations in
this Technical Report were derived are given in 6.4.1 and 7.5.1. It is possible that the equations do not apply
to liquids significantly different from those tested, particularly to highly viscous liquids.
Although the over-reading equations presented in this Technical Report apply for a wide range of gases and
liquids at appropriate gas-liquid density ratios, evaluating gas flowrates depends on information in addition to
that required in single-phase flow: under certain conditions, a measurement of the pressure loss is sufficient;
tracers can be used to measure the liquid flow; the total mass flowrate may be known (this is more likely in a
wet-steam flow than in a natural gas/liquid flow); in a wet-steam flow a throttling calorimeter can be used.
Wet-gas measurement using Venturi tubes or orifice plates is covered in this Technical Report.
This Technical Report is only applicable to wet gas flows with a single liquid and is not intended for the oil and
gas industry.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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 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 5167-4:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 4: Venturi tubes
ISO/TR 15377, Measurement of fluid flow by means of pressure-differential devices — Guidelines for the
specification of orifice plates, nozzles and Venturi tubes beyond the scope of ISO 5167
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4006, ISO 5167-1 and the following
apply.
3.1
stratified flow
common regime in horizontal pipes at low gas velocities (typically 5 m/s or less) in which the free liquid runs
along the bottom of the pipe with the gas flowing at the top of the pipe
3.2
annular flow
flow regime that in horizontal pipes occurs at medium gas velocities (typically 5 m/s to 15 m/s) in which the
liquid flows around the pipe wall with the gas flowing through the centre of the pipe
NOTE In horizontal pipes, annular flow is not uniform; owing to gravitational effects, the liquid is present in higher
quantities around the wall at the bottom of the pipe than higher up the pipe wall.
3.3
mist flow
flow regime that in horizontal pipes requires high gas velocities (typically 15 m/s or higher) to keep the liquid
suspended in the gas and describes liquid in the flow being carried along in small-droplet form within the body
of gas
3.4
slug flow
flow regime in which liquid travels along the pipe intermittently but in significant quantity, often due to the liquid
becoming trapped in the flow line, for example at the bottom of a vertical pipe or when the flow is started after
shutdown
3.5
liquid volume fraction
LVF
ratio of the liquid volume flowrate to the total volume flowrate, where the total volume flowrate is the sum of
the liquid volume flowrate and the gas volume flowrate, all volume flowrates being at actual (not standard)
conditions
3.6
gas volume fraction
GVF
ratio of the gas volume flowrate to the total volume flowrate, where the total volume flowrate is the sum of the
liquid volume flowrate and the gas volume flowrate, all volume flowrates being at actual (not standard)
conditions
4 Symbols and subscripts
See Table 1.
5 Principle of the method of measurement and computation
5.1 Principle of the method of measurement
The principle of the method of measurement
...