SIST EN ISO 7278-1:1998

SLOVENSKI STANDARD
SIST EN ISO 7278-1:1998
01-maj-1998
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Liquid hydrocarbons - Dynamic measurement - Proving systems for volumetric meters -
Part 1: General principles (ISO 7278-1:1987)
Flüssige Kohlenwasserstoffe - Dynamische Messung - Prüfsysteme für volumetrische
Meßgeräte - Teil 1: Allgemeine Grundlagen (ISO 7278-1:1987)
Hydrocarbures liquides - Mesurage dynamique - Systemes d'étalonnage des compteurs
volumétriques - Partie 1: Principles généraux (ISO 7278-1:1987)
Ta slovenski standard je istoveten z: EN ISO 7278-1:1995
ICS:
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
SIST EN ISO 7278-1:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7278-1:1998

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SIST EN ISO 7278-1:1998

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SIST EN ISO 7278-1:1998

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SIST EN ISO 7278-1:1998
ISO
INTERNATIONAL STANDARD
7278-1
First edition
1987-03-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXaYHAPOflHAR OPTAHM3A~MR fl0 CTAHjJAPTM3AqMM
Liquid hydrocarbons - Dynamit measurement -
Proving Systems for volumetric meters -
Part 1:
General principles
Hydrocarbures liquides
- Mesurage dynamique - Systemes d’etalonnage des compteurs
vofum&iques -
Partie 1: Principes ghkaux
Reference number
ISO 7278-1 : 1987 (E)

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SIST EN ISO 7278-1:1998
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of
national Standards bodies (ISO member bedies). The work of preparing International
Standards is normally carried out through ISO technical committees. Esch 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, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 7278-1 was prepared by Technical Committee ISO/TC 28,
Petroleum products and lubricants.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
0 International Organkation for Standardkation, 1987
Printed in Switzerland

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SIST EN ISO 7278-1:1998
INTERNATIONAL STANDARD ISO 7278-1: 1987 (E)
Dynamit measurement -
Liquid hydrocarbons -
Proving Systems for volumetric meters -
Part 1:
General principles
for all liquids and flow rates, provided that the master meter
0 Introduction
is proved against acceptable proving Systems under condi-
This document is the first part of an International Standard on tions which simulate those under which it will operate.
proving Systems for meters used in dynamic measurement of
Sometimes, a meter is used as a means of standardization
liquid hydrocarbons. Future Parts of ISO 7278 will provide more
of transfer; this equipment is generally known as a “master
detailed descriptions of pipe provers, tank provers and pulse
meter”.
interpolation techniques; these Parts are in preparation. Parts
covering other aspects or types of proving Systems may be
3.2 Provers tan be used either connected (fixed or mobile) to
added as the need arises.
the metering Station or in a central proving Station to which the
meters or the measures tan be taken to be proved.
The purpose of proving a meter is to determine its relative error
or its meter factor as a function of flow rate and other
3.3 In Order to limit the maximum uncertainty to + 0,Ol %
Parameters such as temperature, pressure and viscosity.
when using a pulse generator for proving, at least
10 000 pulses shall be obtained from the meter per proving run.
The purpose of determining the relative error is to find out
This number of pulses tan be reduced by pulse-interpolation
whether the meter is working within prescribed or specially ac-
techniques which allow either the use of meters with fewer
cepted limits of error, whereas the meter factor is used to cor-
pulses per unit volume or reduction of the prover volume.
rect any error in the indication of a meter by calculation.
4
General considerations
1 Scope and field of application
This part of ISO 7278 provides general principles for proving 4.1 A meter should be proved at the expected operating or
Systems for meters used in dynamic measurement of liquid prescribed or agreed rates of flow, under the pressure and
hydrocarbons. temperature at which it will operate and on the liquid which it
will measure. In situations where it is not feasible to prove the
meter on the liquid to be metered, the meter should be proved
2 Reference
on a liquid having a density, viscosity and, if possible,
temperature as close as possible to those of the liquid to be
h ydrocarbons - D ynamic measuremen t-
ISO 4124, Liquid
measured. A meter that is used to measure several different
Statistical con trol of volumetric me tering s ys tems. 1 )
liquids shall be proved on each such liquid. Similar liquids may
be used if a simple, known relationship exists between the
relative error, flow rate and viscosity, provided that the uncer-
3 Types of prover
tainty of measurement remains within acceptable limits. In any
event, calibration should take place at a flow rate equivalent to
31 . The following types of proving Systems are in use:
that at which the meter will be used.
tank prover Systems; A meter shall be proved in different circumstances as follows:
a)
bidirectional and unidirectional. Pipe a) Initial proving. This shall be carried out on the perma-
b) pipe provers,
provers with precision tubes as described in 6.7 are available nent location or in a central Station where the expected con-
ditions of Operation tan be reproduced. The initial proving
for special applications;
makes it possible to determine the relationship between the
ndirect procedure of volume com-
c) master meters. I relative error (or meter factor) and different Parameters such
parison which Causes additio nal uncertainties tan be used
as viscosity or temperature. ’
1) At present at the Stage of draft.

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SIST EN ISO 7278-1:1998
b) Occasional or periodical proving. If a simple relationship In the first, a meter tan be proved to establish its Performance
between the relative error (or meter factor) and influencing by adjustment of its registration, if necessary, to give a meter
Parameters tan be determined, the meters shail be reproved factor of 1,000 0 so that its indicated volume will be the volume
periodically using a prover either on the site or in a central- of liquid actually delivered (gross volume within desired
ised Station. Otherwise, the meter shall be reproved on the
tolerantes). This is the normal practice for a meter operating on
site whenever significant changes in the influencing par- intermittent deliveries, such as a tank truck meter or a loading
ameters, such as viscosity or temperature, occur. Regular rack meter at a terminal or bulk plant.
provings are also needed to follow effects of mechanical
changes. In the second, a meter tan be proved to determine its meter
factor or, if possible, a simple relationship between its meter
factor and influencing Parameters such as viscosity or
4.2 Many petroleum liquids of high vapour pressures are
temperature so that this factor or this relationship tan be
measured by meter-. If liquid evaporation during normal opera-
applied to the indicated volume to compute the gross volume
tion or proving could occur and affect measurement, the prov-
delivered through the meter. This is the normal practice in the
ing System should provide means to avoid evaporation.
case of continuous or long-duration measurement.
4.3 The proving of a meter is like a laboratory test: when
4.7 When a meter is being proved for adjustment, a
properly done, it provides a high degree of repeatability, which
preliminary unrecorded run shall be made, as necessary, to
is necessary for measurement accuracy. There are as many
equalise temperatures, displace vapours or gases and wet the
details of the meter, its piping and the proving Systems, which
interior of the prover. Subsequent recorded proving test runs
tan contribute to measurement uncertainty, as there are in
shall be made in the required range of flow rates and the
determining physical properties of the measured liquid. Fur-
registration adjusted as necessary.
thermore, the proving System shall be maintained in good oper-
Thorough inspection of provers and their
ating condition.
Esch calibration Point for the same flow should be repeated at
ancillary equipment should be made with sufficient frequency
least twice and preferably three times. Further repeats may be
to ensure reproducibility of proving results. lt is essential that
necessary, if specified. See ISO 4124.
meter Performance data be observed, recorded and studied and
that calculations be correct (sec ISO 4124).
4.8 When a meter is being proved to determine the meter
factor at one or several flow rates, the procedure shall be
The accuracy and repeatability of the proving tan be affected
esssentially as specified in 4.7, except that no changes shall be
by Observation errors in determining the opening meter reading
made to the meter registration adjusting device between runs.
or the closing meter reading, the test volume passing through
Proof runs shall be made and recorded until the specified
or delivered to the prover and in reading temperature and
number of consecutive runs at the same flow rate agree within
pressure, and by implicit errors in computation in the process of
an acceptable repeatability, at which Point the average of these
correcting a measurement to Standard conditions.
two runs shall be accepted as the established meter correction
factor for this flow rate.
classif ied according to procedure,
4.4 Meter proving tan be
as described below.
4.9 If the registration of a meter, during proving, is not
changing in accordance with adjustments made to the register
a) The standing Start-and-stop procedure uses registers
adjusting device, or if four individual unadjusted proving runs
(counters) from which the opening and closing readings are
are made without any two successive runs checking within an
obtained at no-flow conditions. Qpening and closing of
acceptable repeatability, all phases of the proving Operation
valves shall be performed rapidly.
shall be examined for the Cause of the discrepancy. If the Cause
is not found, the meter and its register mechanisms shali be
b) The running Start-and-stop procedure involves obtain-
inspected for electronie or mechanical defects, repaired and
ing the opening and closing meter readings of the proof
proved before being returned to Service.
while the meter is in Operation. This is accomplished by the
use of auxiliary or secondary registers of high discrimination
4.10 The practical limit of accuracy in any observed value
which tan be started and stopped while the meter and
such as the volume in the reference vessel during a meter proof
primary register continue to operate.
is one part in 10 000. For this reason, meter factors shall be
rounded to four decimal places, not more and not less, for
4.5 Every meter proof shall be made with the same register
example 1,001 6.
equipment as is used in regular Operation or with additional
synchronised auxiliary registers for the running Start-and-stop
4.11 The results of calculation tan be adversely affected by
procedure L4.4 b)]. Inclusion of special auxiliary equipment
the use of abbreviated tables, the unstandardized rounding
such as the following is permitted: density selector,
of factors and/or intermediate calculations. The observed and
temperature compensator, and quantity-predetermining
computed data for all test runs made in obtaining a meter factor
register. If employed, the auxiliary equipment shall be set and
or other expression of meter Performance shall be reported on a
operative when making the proof runs. Time between proving
suitable meter proving report form. The completed form, when
runs shall be kept to a minimum.
signed by the interested Parties or by the legal authority, shall
constitute approval, understanding and acceptance of the
proving which
4.6 There arc two general objectives to meter
meter proof, unless otherwise limited to witnessing only by a
usually depend on the type 0% Service.
notation on the report.
2

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SIST EN ISO 7278-1:1998
ISO 7278-1: 1987 (E)
4.12 Most of the procedures specifie
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