ISO 10790:1999/Amd 1:2003
(Amendment)Measurement of fluid flow in closed conduits — Guidance to the selection, installation and use of Coriolis meters (mass flow, density and volume flow measurements) — Amendment 1: Guidelines for gas measurement
Measurement of fluid flow in closed conduits — Guidance to the selection, installation and use of Coriolis meters (mass flow, density and volume flow measurements) — Amendment 1: Guidelines for gas measurement
Mesure de débit des fluides dans les conduites fermées — Lignes directrices pour la sélection, l'installation et l'utilisation des mesureurs à effet Coriolis (mesurages de débit-masse, masse volumique et débit-volume) — Amendement 1: Lignes directrices pour le mesurage des gaz
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INTERNATIONAL ISO
STANDARD 10790
Second edition
1999-05-01
AMENDMENT 1
2003-06-01
Measurement of fluid flow in closed
conduits — Guidance to the selection,
installation and use of Coriolis meters
(mass flow, density and volume flow
measurements)
AMENDMENT 1: Guidelines for gas
measurement
Mesure de débit des fluides dans les conduites fermées — Lignes
directrices pour la sélection, l'installation et l'utilisation des mesureurs à
effet Coriolis (mesurages de débit-masse, masse volumique et débit-
volume)
AMENDEMENT 1: Lignes directrices pour le mesurage des gaz
Reference number
ISO 10790:1999/Amd.1:2003(E)
©
ISO 2003
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ISO 10790:1999/Amd.1:2003(E)
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ii © ISO 2003 — All rights reserved
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ISO 10790:1999/Amd.1:2003(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.
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.
Amendment 1 to ISO 10790:1999 was prepared by Technical Committee ISO/TC 30, Measurement of fluid
flow in closed conduits, Subcommittee SC 5, Velocity and mass methods.
This Amendment contains additional considerations and guidelines for the use of Coriolis meters in gas flow
measurements.
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ISO 10790:1999/Amd.1:2003(E)
Measurement of fluid flow in closed conduits — Guidance to
the selection, installation and use of Coriolis meters (mass flow,
density and volume flow measurements)
AMENDMENT 1: Guidelines for gas measurement
Page 1, Scope
Replace Clause 1 with the following:
1 Scope
This International Standard gives guidelines for the selection, installation, calibration, performance and
operation of Coriolis meters for the determination of mass flow, density, volume flow and other related
parameters of fluids, synonymous for liquids and gases as a first approach. For gases, it gives the
determination of gas mass flow and standard volume flow (using predetermined standard density). It also
gives appropriate considerations regarding the fluids to be measured.
The primary purpose of Coriolis meters is to measure mass flow. However, some of these meters offer
additional possibilities for determining the density and temperature of fluids. From the measurement of these
three parameters, volume flow and other related parameters can be determined.
Measurements of gas flow, in principle, are possible using any Coriolis meter if special considerations are
made. Specific considerations for gas flow measurements are given in Annex E.
The content of this International Standard is primarily applicable to the metering of liquids and where possible
to gas measurements.
Page 3, Clause 2
Replace entries 2.12 and 2.13 with the following:
2.12
flashing
〈liquids〉 phenomenon which occurs when the line pressure drops to, or below, the vapour pressure of the
liquid
NOTE 1 This is often due to pressure drops caused by an increase in liquid velocity.
NOTE 2 Flashing is not applicable to gases.
2.13
cavitation
〈liquids〉 phenomenon related to and following flashing if the pressure recovers causing the vapour bubbles to
collapse (implode)
NOTE Cavitation is not applicable to gases.
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ISO 10790:1999/Amd.1:2003(E)
Page 3, Clause 2
Add the following new entries 2.14 to 2.17:
2.14
relative humidity
actual amount of water vapour contained in a gas as a percentage of the maximum water vapour content if the
gas was fully saturated at metering conditions
2.15
choked flow
maximum flowrate for a particular geometry which can exist for the given upstream conditions
NOTE 1 When choked flow occurs, the velocity at a cross-section is equal to the local value of the speed of sound
(acoustic velocity), the velocity at which small pressure disturbances propagate.
NOTE 2 Choked flow can occur either at the inlet or the outlet of a Coriolis meter.
2.16
shock wave
discontinuity in supersonic flow across which there is a sudden rise in pressure and temperature
2.17
critical nozzle
Venturi nozzle for which the nozzle geometrical configuration and conditions of use are such that the flowrate
is critical
NOTE See also ISO 9300.
After page 28, after Annex D
Add new Annex E as follows:
Annex E
(normative)
Guidelines for gas measurement
E.1 General
This annex gives guidelines that are specifically applicable to gas measurements using Coriolis meters.
E.2 Coriolis meter selection criteria
E.2.1 General
The Coriolis meter should be selected to measure mass flow within the required range and accuracy.
However, since noise is created by high flow velocities usually present in gas applications, achievable mass
flow rates are normally lower than for liquid applications.
Consideration should be given to the points given in E.2.2 to E.2.6 when selecting a Coriolis meter.
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ISO 10790:1999/Amd.1:2003(E)
E.2.2 Accuracy
The expression of accuracy varies depending on the parameter to which it applies. For specific
recommendations on mass flow, see 5.2.
Manufacturers’ accuracy statements should be given for specified reference conditions. If the conditions of
use are significantly different from those of the original calibration, the meter's performance can be affected.
E.2.3 Physical installation
E.2.3.1 General
The manufacturer should describe the preferred installation arrangement and state any restrictions of use.
See Annex C.
The installation arrangement should be designed to provide a maximum operating lifetime. If required,
strainers, filters, separators or other protective devices should be placed upstream of the meter for the
removal of solids or condensate that could cause damage or provoke errors in measurement.
E.2.3.2 Orientation
Coating, trapped condensate or settlement of solids can affect the meter's performance. The orientation of the
sensor will depend on the intended application of the meter and the geometry of the oscillating tube(s). The
orientation of the Coriolis meter should be recommended by the manufacturer to minimize these effects.
E.2.3.3 Valves
Valves upstream and downstream of a Coriolis meter, installed for the purpose of isolation and zero
adjustment, can be of any type, but should provide tight shutoff. Control valves in series with a Coriolis meter
should be installed downstream in order to maintain the highest possible pressure.
Due to the high velocities encountered in gas flow, acoustic noise may be generated by valves. This may
interfere with the meter performance. Care should be taken in selecting the type of valve and its location.
E.2.3.4 Cleaning
In certain applications (for instance asphalt deposits from gas), the Coriolis meter may require in-situ cleaning
which can be accomplished by:
a) mechanical means (using a pig or ultrasonically);
b) hydrodynamic means:
sterilization (steaming-in-place, SIP);
chemical or biological (cleaning-in-place, CIP).
Care should be taken to avoid cross-contamination after cleaning fluids have been used.
Chemical compatibility should be established between the sensor wetted-materials, process fluid and cleaning
fluid.
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ISO 10790:1999/Amd.1:2003(E)
E.2.4 Effects due to process conditions and fluid properties
E.2.4.1 General
Variations in fluid properties such as density and process conditions such as pressure and temperature, may
influence the meter’s performance. These effects have influences which differ depending on which parameter
is of interest. See 5.3.
E.2.4.2 Application and fluid properties
In order to identify the optimum meter for a given application, it is important to establish the range of
conditions to which the Coriolis meter will be subjected. These conditions should include:
a) the operating flow rates and the following flow characteristics:
unidirectional or bi-directional,
continuous, intermittent or fluctuating;
b) the range of operating densities;
c) the range of operating temperatures;
d) the range of operating pressures;
e) the permissible pressure loss;
f) the properties of the metered gas, including relative humidity, two-phase flow and corrosiveness;
g) the effects of corrosive additives or contaminants on the meters and the quantity and size of foreign
matter, includin
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