ISO 12242:2012
(Main)Measurement of fluid flow in closed conduits — Ultrasonic transit-time meters for liquid
Measurement of fluid flow in closed conduits — Ultrasonic transit-time meters for liquid
ISO 12242:2012 specifies requirements and recommendations for ultrasonic liquid flowmeters, which utilize the transit time of ultrasonic signals to measure the flow of single-phase homogenous liquids in closed conduits. There are no limits on the minimum or maximum sizes of the meter. ISO 12242:2012 specifies performance, calibration and output characteristics of ultrasonic meters (USMs) for liquid flow measurement and deals with installation conditions. It covers installation with and without a dedicated proving (calibration) system. It covers both in-line and clamp-on transducers (used in configurations in which the beam is non-refracted and in those in which it is refracted). Included are both meters incorporating meter bodies and meters with field-mounted transducers.
Mesurage de débit des fluides dans les conduites fermées — Compteurs ultrasoniques pour liquides
General Information
Standards Content (Sample)
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Measurement of fluid flow in closed
conduits — Ultrasonic transit-time
meters for liquid
Mesurage de débit des fluides dans les conduites fermées —
Compteurs ultrasoniques pour liquides
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Published in Switzerland
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Contents Page
Foreword . v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantities . 1
3.2 Meter design . 2
3.3 Thermodynamic conditions . 3
3.4 Statistics . 3
3.5 Calibration . 5
3.6 Symbols and subscripts . 5
3.7 Abbreviated terms . 7
4 Principles of measurement . 7
4.1 Description . 7
4.2 Volume flow . 9
4.3 Generic description .10
4.4 Time delay considerations . 11
4.5 Refraction considerations .14
4.6 Reynolds number .15
4.7 Temperature and pressure correction .15
5 Performance requirements .15
6 Uncertainty in measurement .16
6.1 Introduction .16
6.2 Evaluation of the uncertainty components .16
7 Installation .18
7.1 General .18
7.2 Use of a prover .19
7.3 Calibration in a laboratory or use of a theoretical prediction procedure .19
7.4 Additional installation effects .21
8 Test and calibration .22
8.1 General .22
8.2 Individual testing — Use of a theoretical prediction procedure .22
8.3 Individual testing — Flow calibration under flowing conditions .23
9 Performance testing .24
9.1 Introduction .24
9.2 Repeatability and reproducibility .25
9.3 Additional test for meters with externally mounted transducers .25
9.4 Assessing the uncertainty of a meter whose performance is predicted using a theoretical
prediction procedure .26
9.5 Fluid-mechanical installation conditions .26
9.6 Path failure simulation and exchange of components .27
10 Meter characteristics .27
10.1 Meter body, materials, and construction .27
10.2 Transducers .29
10.3 Electronics .29
10.4 Software .30
10.5 Exchange of components .31
10.6 Determination of density and temperature .31
11 Operational practice .32
11.1 General .32
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11.2 Audit process .32
11.3 Operational diagnostics .34
11.4 Audit trail during operation; inter-comparison and inspection .36
11.5 Recalibration .37
Annex A (normative) Temperature and pressure correction .42
Annex B (informative) Effect of a change of roughness .48
Annex C (informative) Example of uncertainty calculations .52
Annex D (informative) Documents .65
Bibliography .67
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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.
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 12242 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits,
Subcommittee SC 5, Velocity and mass methods�
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Introduction
Ultrasonic meters (USMs) have become one of the accepted flow measurement technologies for a wide range
of liquid applications, including custody-transfer and allocation measurement. Ultrasonic technology has
inherent features such as no pressure loss and wide rangeability.
USMs can deliver diagnostic information through which it may be possible to demonstrate that an ultrasonic
liquid flowmeter is performing in accordance with specification. Owing to the extended diagnostic capabilities,
this International Standard advocates the addition and use of automated diagnostics instead of labour-intensive
quality checks. The use of automated diagnostics makes possible a condition-based maintenance system.
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INTERNATIONAL STANDARD ISO 12242:2012(E)
Measurement of fluid flow in closed conduits — Ultrasonic
transit-time meters for liquid
1 Scope
This International Standard specifies requirements and recommendations for ultrasonic liquid flowmeters,
which utilize the transit time of ultrasonic signals to measure the flow of single-phase homogenous liquids in
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There are no limits on the minimum or maximum sizes of the meter.
This International Standard specifies performance, calibration and output characteristics of ultrasonic meters
(USMs) for liquid flow measurement and deals with installation conditions. It covers installation with and without
a dedicated proving (calibration) system. It covers both in-line and clamp-on transducers (used in configurations
in which the beam is non-refracted and in those in which it is refracted). Included are both meters incorporating
meter bodies and meters with field-mounted transducers.
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 4006, Measurement of fluid flow in closed conduits — Vocabulary and symbols
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4006 and the following apply.
3.1 Quantities
3.1.1
volume flowrate
q
V
�V
q =
V
�t
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NOTE Adapted from ISO 80000-4:2006, 4-30.
3.1.2
metering pressure
absolute fluid pressure in a meter under flowing conditions to which the indicated volume of liquid is related
3.1.3
mean velocity in the meter body
v
fluid flowrate divided by the cross-sectional area of the meter body
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3.1.4
mean pipe velocity
v
p
fluid flowrate divided by t
...
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