Experimental data for the determination of 100mm orifice meter discharge coefficients under different installation conditions

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Commission of the European Communities
Community Bureau of Reference
BCR Information
APPLIED METROLOGY
EXPERIMENTAL DATA FOR THE DETERMINATION
OF 100 mm ORIFICE METER
DISCHARGE COEFFICIENTS
UNDER DIFFERENT INSTALLATION CONDITIONS
(EUROPEAN PROGRAMME)
Report
EUR 10774 EN
Blow-up from microfiche original Commission of the European Communities
Community Bureau of Reference
BCR Information
APPLIED METROLOGY
EXPERIMENTAL DATA FOR THE DETERMINATION
OF 100 mm ORIFICE METER
DISCHARGE COEFFICIENTS
UNDER DIFFERENT INSTALLATION CONDITIONS
(EUROPEAN PROGRAMME)
Compiled by
J.M. HOBBS, J.A. SATTARY
National Engineering Laboratory
UK-East Kilbride, Glasgow
From reports supplied by
Gaz de France
361, Av. du Président Wilson
F - 93211 La Plaine St. Denis
Nederlandse Gasunie N.V.
Postbus 19
NL - 9700 MA Groningen
and
National Engineering Laboratory
Contract No. 3031/1/0/016/85/2-BCR-UK(30)
Work performed under contract
from the Commission of the European Communities
PAP'. r" . VM
i:.c
Directorate-General Science, Research and Development
1987 ?1 IR 10.774 FN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of then is responsible for the use which might be made of the following
information
© ECSC—EEC—EAEC Brussels - Luxembourg, 1987 EXPERIMENTAL DATA FOR THE DETERMINATION OF 100 mm ORIFICE METER
DISCHARGE COEFFICIENTS UNDER DIFFERENT INSTALLATION CONDITIONS
(EUROPEAN PROGRAMME)
SUMMARY
This report presents the results of calibrations of 'thin' 100 mm orifice
plates of diameter ratios 0.57 and 0.75 made under various installation
conditions with and without the use of flow straighteners. Data were
obtained by NEL using air and water and by Gasunie and Gaz de France using
natural gas.
These investigations form part of the EEC programme which has the objective
of verifying or improving the values predicted for the discharge coefficient
of orifice plate flowmeters.
Ill CONTENTS
Page
1 INTRODUCTION 1
2 TEST FACILITIES USED
2.1 NEL Water Flow Facility !
2.2 NEL Gravimetric Gas Flow Standard 2
2.3 Gasunie Research Flow Rig
2.4 Gaz de France Test Facility 3
3 FLOW STRAIGHTENERS USED
4 TESTS CARRIED OUT
4.1 In NEL Water Facility 4
4.2 Using NEL Gravimetric Gas Flow Standard 5
4.3 By Gasunie in Natural Gas
4.4 By Gaz de France in Natural Gas
5 TABULATED DATA 6
REFERENCES 7
LIST OF TABLES 8
LIST OF FIGURES g
INDEX OF DATA PRESENTED 9 1 INTRODUCTION
This project to check and improve the method of prediction of the discharge
coefficients of orifice plates was begun in 1979. Metering sections were
manufactured in two sizes (100 and 250 mm) for tests in each of the par­
ticipating laboratories in turn. For both pipe sizes sets of six 'thin'
and six 'thick' orifice plates were made in stainless steel to ASTM 316,
each set having nominal diameter ratios of 0.2, 0.375, 0.5, 0.57, 0.66 and
0.75. The different thicknesses were chosen such that the thinner plates
complied with the requirements of AGA 3 and ISO 5167; the thick plates were
the maximum permitted by ISO 5167.
The objective of the second phase of the test programme was to determine
the discharge coefficients for thin 100 mm orifice plates of 0.57 and 0.75
diameter ratio under different installation conditions both with and
without flow straighteners.
This report presents, without comment, the data obtained at NEL using water
and air, and at Gasunie and Gaz de France using natural gas. A comprehen­
sive analysis of the data will be the subject of a future report, but all
the results obtained under different installation conditions are presented
here so that the reader may carry out his own analysis if he wishes.
The 100 mm test section assembly was designed and manufactured by Daniel
Industries (UK) Ltd. A dimensional inspection of the component parts of
the assembly and of all the orifice plates was made at NEL*1*.
A large number of measurements were made including the bore, outside dia­
meter, thickness, surface finish and edge sharpness for each plate. The
major dimensions are given in Table 1.
The internal diameter of the pipe was measured at four equally spaced dia­
meters in each of the planes between the flange face and a distance 2 x D
upstream. The mean value of all these measurements was 4.024 inches. The
mean pipe diameter determined as specified in ISO 5167 and AGA 3 both gave
a value of 4.024 inches and this value was therefore adopted by all par­
ticipating laboratories for use in calculations.
Critical measurements (such as edge sharpness) were repeated at each lab­
oratory to ensure the condition of the plates remained unchanged, but to
ensure compatibility of the results the dimensions obtained by NEL were
used for all calculations in the various laboratories.
Three tapping arrangements were used for the tests, namely corner, flange
and D, D/2. Each configuration consisted of a pair of diametrically
opposed pressure tap drillings in each of the upstream and downstream
halves of the measuring section.
2 TEST FACILITIES USED
2.1 NEL Water Flow Facility
The NEL water flow facilities constitute the UK primary standard for flow
measurement*2' (Fig. 1). Water is pumped from a sump containing about
270 a3 to a constant-head tank. From there it flows by gravity through the
meter to be calibrated, through a flow control valve and then back to the
sump. For high flowrates or when the system resistance is high, the water
can be pumped directly to the test-lines. When conditions are steady the discharge from the control valve can be diverted for an accurately measured
time into any one of a series of collecting tanks each mounted on a
weighing machine.
The mass of the water diverted was determined by taking a static weighing
of the tank before and after the diversion using an accurately calibrated
steelyard weighing machine» (On the newer machines load cells are also
incorporated to facilitate the use of a data acquisition system.) The
weight difference was corrected for buoyancy to give the true mass of the
water diverted.
The density of the water relative to that of distilled water was measured
for each test run and, using approved values of the density of distilled
water, the density of the water flowing through the metering section was
determined. Hence mass flow could be converted to volume flowrates.
Pressure differences between the orifice plate tappings were measured using
water/air and mercury/water manometer banks. An uncertainty of ±3 mm water
and ±2 mm mercury applied to these measurements. These values are
reflected in the random uncertainty of the observations.
All the weighings were taken using the three-tonne capacity weightank. The
flows covered a pipe Reynolds number range from 6800-822 000 and the
systematic uncertainty of the flowrate was estimated at ±0.2 per cent.
Summing the random and systematic uncertainties in quadrature at the 95 per
cent confidence level gives the overall uncertainty in the discharge coef­
ficient.
2.2 NEL Gravimetric Gas Flow Standard
The HEL high pressure gas flow facility, also a British National Standard,
which has been described in detail in Reference 3, is shown in Fig. 2.
Purified air from the compressor plant was used to charge the storage
pressure vessel and the control loop. Air from the loop passes through the e control system B and valve X to the test-line. The tests were
carried out using the secondary standard sonic nozzles, which were
previously calibrated by means of the weighing vessel.
A betz micromanometer with a range of 800 mm water gauge and uncertainty of
±0.1 mm water was used to measure the pressure differences across each
orifice plate. A similar manometer was used to measure the line static
pressure upstream of the orifice plate. For some tests a Wallace and
Tiernan precision dial pressure gauge (of range 0-7 bar and uncertainty of
±0.1 per cent) was used to measure orifice plate upstream static pressure.
Two platinum resistance thermometers, each with an uncertainty of ±0.1°C
were used to measure the temperature in the line at the reference standard
nozzle and at the orifice plate. The temperature of the manometer was
measured using a mercury-in- glass thermometer having an uncertainty of
±0.2°C.
Density of the air was calculated from the universal gas constant according
to the usual gas laws.
2.3 Gasunie Research Flow Rig
In the research flow rig at Groningen*1*) (Fig. 3) natural gas is drawn from
a high-pressure transmission pipeline at 38 bar. After flowing through the