Measurement of fluid flow by means of pressure-differential devices — Guidelines to the effect of departure from the specifications and operating conditions given in ISO 5167-1

Mesurage du débit des fluides au moyen d'appareils déprimogènes — Lignes directrices relatives aux effets de divergence par rapport aux spécifications et conditions de fonctionnement données dans l'ISO 5167-1

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REPORT 12767
First edition
Measurement of fluid flow by means of
pressure-differential devices — Guidelines
to the effect of departure from the
specifications and operating conditions
given in ISO 5167-1
Mesurage du débit des fluides au moyen d’appareils déprimogènes —
Lignes directrices relatives aux effets de divergence par rapport aux
spécifications et conditions de fonctionnement données dans l’ISO 5167-1
Reference number
ISO/TR 12767:1998(E)
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ISO/TR 12767:1998(E)

1 Scope ........................................................................................................................................................................1

2 Reference..................................................................................................................................................................1

3 Symbols and definitions .........................................................................................................................................1

4 Effect of errors on flowrate calculations..............................................................................................................3

5 Effects of deviations in construction.....................................................................................................................3

6 Effects of pipeline near the meter ..........................................................................................................................6

7 Effects of pipe layout ............................................................................................................................................13

8 Operational deviations ..........................................................................................................................................17

9 Pipe roughness......................................................................................................................................................24

Annex A Bibliography ............................................................................................................................................29

© ISO 1998

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic

or mechanical, including photocopying and microfilm, without permission in writing from the publisher.

International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Printed in Switzerland
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ISO/TR 12767:1998(E)

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.

The main task of technical committees is to prepare International Standards. In exceptional circumstances a

technical committee may propose the publication of a Technical Report of one of the following types:

— type 1, when the required support cannot be obtained for the publication of an International Standard, despite

repeated efforts;

— type 2, when the subject is still under technical development or where for any other reason there is the future

but not immediate possibility of an agreement on an International Standard;

— type 3, 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).

Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they

can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be

reviewed until the data they provide are considered to be no longer valid or useful.

ISO/TR 12767, which is a Technical Report of type 3, was prepared by Technical Committee ISO/TC 30,

Measurement of fluid flow in closed conduits, Subcommittee SC 2, Pressure-differential devices.

Annex A of this Technical Report is for information only.
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ISO/TR 12767:1998(E)

ISO 5167-1 is an International Standard for flowrate measurement using a differential-pressure device. Adherence

to that standard will result in flowrate measurements the uncertainty of which will lie within specified limits. If,

however, a flowmetering installation departs, for whatever reason, from the conditions specified in ISO 5167-1, the

specified limits of uncertainty may not be achieved. Many metering installations exist where these conditions either

have not been or cannot be met. In these circumstances it is usually not possible to evaluate the precise effect of

any such deviations. However, a considerable amount of data exists which can be used to give a general indication

of the effect of non-conformity to ISO 5167-1, and it is presented in this Technical Report as a guideline to users of

flow-metering equipment.
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Measurement of fluid flow by means of pressure-differential
devices — Guidelines to the effect of departure from the
specifications and operating conditions given in ISO 5167-1
1 Scope

This Technical Report provides guidance to assist in estimating the flowrate when using pressure-differential

devices constructed or operated outside the scope of ISO 5167-1.

It should not be inferred that additional tolerances or corrections can necessarily compensate for the effects of

deviating from ISO 5167-1. The information is given, in the first place, to indicate the degree of care necessary in

the manufacture, installation and maintenance of pressure-differential devices by describing some of the effects of

non-conformity to the requirements; and in the second place, to permit those users who may not be able to comply

fully with the requirements to assess, however roughly, the magnitude and direction of the resulting error in flowrate.

Each variation dealt with is treated as though it were the only one present. Where more than one is known to exist,

there may be unpredictable interactions and care has to be taken when combining the assessment of these errors.

If there is a significant number of errors, means of eliminating some of them must be considered. The variations

included in this Technical Report are by no means complete and relate largely to examples with orifice plates. There

are, no doubt, many similar examples of installations not conforming to ISO 5167-1 for which no comparable data

have been published. Such additional information from users, manufacturers and any others may be taken into

account in future revisions of this Technical Report.
2 Reference

ISO 5167-1:1991, Measurement of fluid flow by means of pressure-differential devices — Part 1: Orifice plates,

nozzles and Venturi tubes inserted in circular cross-section conduits running full.

3 Symbols and definitions
3.1 Symbols
For the purposes of this Technical Report, the symbols given in Table 1 apply.
3.2 Definitions

For the purposes of this Technical Report, the definitions given in ISO 5167-1 and the following definitions apply.

square edge

angular relationship between the orifice bore of the flow measurement device and the upstream face, when the

angle between them is 90° ± 0,3°

radius of the edge between the orifice bore of the flow measurement device and the upstream face

NOTE The upstream edge of the orifice bore is considered to be sharp when its radius is not greater than 0,0004 d, where

d is the diameter of the orifice bore.
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ISO/TR 12767:1998(E)
Table 1 — Symbols
Symbol Represented quantity Dimensions SI units
M: mass
L: length
T: time
� �
c dimensionless
Percentage change in discharge coefficient
�” 100 �
Ł ł
C Discharge coefficient dimensionless
C Contraction coefficient dimensionless
d Diameter of orifice or throat of primary device at operating conditions L m
D Upstream internal pipe diameter at operating conditions L m
D Carrier ring diameter L m
D Orifice plate support diameter L m
e Relative uncertainty dimensionless
E Orifice plate thickness L m
E Thickness of orifice L m
k Uniform equivalent roughness L m

L Distance of upstream pressure tapping from upstream face of plate divided dimensionless

by pipe bore (D)

L' Distance of downstream pressure tapping from downstream face of plate dimensionless

divided by pipe bore (D)
q Mass rate of flow kg/s
r Orifice plate edge radius L m
Re Reynolds number based on upstream pipe diameter dimensionless
Re Reynolds number based on throat bore of device dimensionless
S Distance from upstream fitting to straightener L m
S Distance from straightener to primary device L m
S Distance from primary device to downstream fitting L m
u Local axial velocity m/s
Centreline axial velocity -1 m/s
U Mean axial velocity m/s
-1 -2
Y Modulus of elasticity of orifice plate material Pa
β Diameter ratio, β = d/D dimensionless
-1 -2
Δp Differential pressure Pa
-1 -2
Δp Differential pressure required to reach orifice plate yield stress Pa

ε Expansibility (expansion) factor at the upstream pressure tapping dimensionless

λ Friction factor dimensionless
ρ Fluid density
3 3
Fluid density at the upstream pressure tapping -
ML kg/m
-1 -2
σ Yield stress of orifice plate material Pa
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ISO/TR 12767:1998(E)
4 Effect of errors on flowrate calculations
4.1 General

In this Technical Report the effects of deviations from the conditions specified in ISO 5167-1 are described in terms

of changes in the discharge coefficient of the meter. The discharge coefficient of a pressure-differential device (C) is

given by the following equation:
41 q ( - b )
C = (1)
pDd (2 pr)

The sharp edge of an orifice plate ensures separation of the flow and consequently contraction of the fluid stream to

the vena contracta. Defining the contraction coefficient, C , as
flow area
geometric area

the orifice produces C ≅ 0,6, which mainly accounts for the discharge coefficient, C ≅ 0,6.

The effect of change in the discharge coefficient is illustrated by the following example.

Consider an orifice plate with an unduly rounded edge. The result of this will be to reduce the separation and

increase Cc, leading in turn to reduced velocities at the vena contracta. The observed differential pressure will

therefore decrease. From the equation above, it can be seen that the discharge coefficient would therefore

increase. Alternatively, as Cc increases so does C. If no correction is made for this change in C, the meter will

under-read (register).
It can therefore be concluded that:

a) an effect which causes an increase in discharge coefficient will result in an under-reading of flow if the

coefficient is not corrected;
and conversely,

b) an effect which causes a decrease in discharge coefficient will result in an over-reading of flow if the coefficient

is not corrected.
4.2 Quantifiable effects

When the user is aware of such effects and they can be quantified, the appropriate discharge coefficient can be

used and the correct flowrate calculated. However, the precise quantification of these effects is difficult and so any

flowrate calculated in such a manner should be considered to have an increased uncertainty.

Except where otherwise stated, an additional uncertainty factor, equivalent to 100 % of the discharge coefficient

correction, should be added arithmetically to that of the discharge coefficient when estimating the overall uncertainty

of the flowrate measurement.
5 Effects of deviations in construction
5.1 Orifice plate edge sharpness

Orifice plates that do not have the specified sharpness of the inlet edge (edge radius r ≤ 0,0004 d in accordance

with of ISO 5167-1 : 1991), will have progressively increasing discharge coefficients as the edge radius

increases. Tests have shown that the effect on the discharge coefficient, C, is to increase it by 0,5 % for r/d of

0,001, and by about 5 % for r/d of 0,01. This is an approximately linear relationship (see figure 1 and Hobbs and

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ISO/TR 12767:1998(E)

Humphreys[1]). These values apply particularly to Re values above 300 000 and for β values below 0,7, but they

can be used as a general guide for other values.

Measurement techniques for edge radius are available, but in general it is better to improve the edge sharpness to

the required value rather than attempt to measure it and make appropriate corrections.

Figure 1 — Effect of edge radius on discharge coefficient
5.2 Thickness of orifice edge

For orifice plates, the increase in discharge coefficient due to the excessive thickness of the orifice edge (see 8.1.4

of ISO 5167-1 : 1991) can be appreciable. With a straight-bore orifice plate in a 150 mm pipe, the changes in

discharge coefficient shown in figure 2 were obtained (see Husain and Teyssandier [2]).

5.3 Condition of upstream and downstream faces of orifice plate

The upstream face should be flat and smooth. Excessive roughness leads to an increase in the discharge

coefficient. Tests have indicated that a surface roughness of 0,0003 d will cause an increase in discharge coefficient

of the order of 0,1 %. Since the requirement for edge sharpness is r ≤ 0,0004 d, an increase in plate roughness will

make it difficult to define or confirm that the sharp edge requirement has been met.

Local damage to the upstream face or edge of an orifice plate does not adversely affect the discharge coefficient

provided that the damage is kept as far away from the pressure tapping as possible (see Hobbs and

Humphreys [1]). The discharge coefficient is much less sensitive to the surface condition of the downstream face of

the plate (Hobbs and Humphreys [1]).

Large scale lack of flatness, e.g. ‘dishing’, leads to flow measurement errors. A ‘dishing’ of 1 % in the direction of

flow will cause an under-reading, i.e. an increase in C, of about 0,2 % for β = 0,2 and about 0,1 % for β = 0,7.

Distortion against the direction of flow also causes errors which could be either positive or negative depending on

the amount of distortion.
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ISO/TR 12767:1998(E)
Figure 2 — Change in discharge coefficient as a function of orifice thickness
5.4 Position of pressure meter tappings for an orifice
5.4.1 General

Values of the orifice plate discharge coefficient for the three standard tapping positions (corner, flange, D and D/2)

can be calculated using the Stolz equation (see of ISO 5167-1 : 1991). Where the tapping positions fall

outside the tolerances permitted in ISO 5167-1 for the three positions, the discharge coefficient may be estimated

as described in 5.4.2. It should be emphasized that an additional uncertainty factor needs to be associated with the

use of non-standard tapping positions.
5.4.2 Calculation of discharge coefficient

Calculate the actual values of L and L' . The discharge coefficient can be estimated only if L ≤ 1 and L' ≤ 0,47.

1 2 1 2

Using the actual values of L and L' , estimate the discharge coefficient using the Stolz equation.

1 2
5.4.3 Estimation of additional uncertainty

If tappings lie between the flange and corner taps, the additional uncertainty (e), expressed as a percentage, can be

estimated from:
e = 25 - 1 (2)
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ISO/TR 12767:1998(E)
C is the discharge coefficient for flange taps;
C is the discharge coefficient for corner taps.

If tappings lie between D and D/ 2 and flange taps, the additional uncertainty (e), expressed as a percentage, can be

estimated from:
DD& /2
e = 25 - 1 (3)
C is the discharge coefficient for D and D/2 taps.
5.4.4 Example

Consider an orifice meter with β = 0,6, Re = 10 , D = 254 mm and tappings at 0,15 D upstream and downstream of

the plate.

To estimate the discharge coefficient, use the Stolz equation with L = L' = 0,15.

1 2

The tappings in this example lie between the flange and D and D/2 tapping positions. From tables A.8 and A.2

respectively of ISO 5167-1 : 1991:
C = 0,6049
C = 0,6067
Therefore, additional uncertainty = 25 - 1 %(4)
= 0,074 %

The uncertainty of the discharge coefficient is 0,6 % (see of ISO 5167-1 : 1991);

Therefore, overall uncertainty = 0,6 + 0,074 ≈ 0,7 % (i.e. the uncertainty has been simply added arithmetically).

5.5 Condition of pressure tappings

Experience has shown that large errors can be created by pressure tappings which have burrs or deposits on, or

close to, the edge where the tapping penetrates the pipe wall. This is particularly the case where the tapping is in

the main flow stream such as throat taps in nozzles or Venturi tubes, where quite small burrs can give rise to

significant percentage errors. Upstream corner tappings and downstream tappings in relatively dead zones are

much less susceptible to this problem.

The installation should be inspected before use and at regular intervals to ensure that these anomalies are not

6 Effects of pipeline near the meter
6.1 Pipe diameter

The internal diameter of the pipe upstream and downstream of the primary device should always be measured to

ensure that it is in accordance with 7.5 and 7.6 of ISO 5167-1 : 1991. Errors in the upstream internal diameter

measurement will cause errors in the calculated rate of flow, which are given by:

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ISO/TR 12767:1998(E)
d q
-2 b dD
= � (5)
q D
( 1- )b

These errors become significant for large β, e.g. with β = 0,75, a positive 1 % error in D will cause a negative 1 %

error in q .

The downstream pipe is far less critical, as its diameter need only be within 3 % of that of the upstream pipe (see of ISO 5167-1 : 1991).
6.2 Steps and taper sections

Sudden enlargements of the pipe in the vicinity of the primary device should always be avoided as large errors in

flow measurement result from their use. Similarly, tapering sections of pipe can lead to significant errors, as can be

seen from Table 2 which gives the order of errors to be expected when an orifice plate with corner tappings is

immediately preceded or followed by a taper piece.

From Table 2 it will be seen that a taper piece divergent in the direction of flow, and placed immediately upstream, is

not recommended, since discharge coefficient increases of up to 50 % are caused. On the other hand, a convergent

taper piece, whether installed before or after the orifice plate, and provided it is not of a steeper angle than those

shown, results in coefficient changes of generally less than 2 %.
6.3 Diameter of carrier ring

The requirements concerning the sizing and concentric mounting of carrier rings for orifice plates and nozzles are

specified in,,, and figure 6 of ISO 5167-1 : 1991. If the requirement of (i.e. that

the centred carrier ring should not protrude into the pipe) is not met, relatively large flow measurement errors will be

introduced. Figure 3 shows such an installation and figure 4, using the same notation, shows the approximate errors

introduced for the given conditions. It is emphasized that in arriving at these errors, the internal diameter of the

carrier ring, D1, and not the diameter of the main line, has been used in determining the calculated flowrate and is to

be used for D in determining the correction factor when making use of the values shown.

Where the carrier is oversize, experimental results indicate that for β = 0,74, a carrier 11 % oversize and extending

0,05 D upstream from the plate increased the discharge coefficient by approximately 0,5 %. However, for a similar

geometry but with β = 0,63, no effect was found.
6.4 Undersize joint rings

When the inside diameter of a joint ring or gasket is smaller than the pipe diameter, especially on the upstream side

of an orifice plate or nozzle, very large flow measurement errors may occur. The magnitude and sign of the effect in

relation to the measurement of flowrate is dependent on the combination of a number of variables, e.g. the

thickness of the joint ring upstream of the orifice plate, the extent of its protrusion into the flow, its position relative to

the orifice plate and pressure tappings, as well as on the degree of roughness of the upstream pipe.

6.5 Protruding welds

The effect of an undressed circumferential weld protruding into the pipe bore adjacent to the primary device will be

similar to that of an undersize joint ring. Such an effect may arise from the fitting of a weld-neck flange, and the

magnitude of the effect will depend on the height uniformity, or otherwise, of the protruding weld, and its position in

relation to the single or multiple pressure tapping arrangement employed to measure the differential pressure

across the primary device. To quantify the resulting error in a specific situation is difficult without a direct calibration.

From 7.1.5 in ISO 5167-1 : 1991 it should be noted that "seamed pipe may be used provided that the internal weld

bead is parallel to the pipe axis throughout the length of the pipe and satisfies the special requirements for the type

of primary element. The seam shall not be situated in any sector of ± 30° centred on any pressure tapping".

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ISO/TR 12767:1998(E)
Table 2 — Effect of taper pieces
Position of orifice plate β Order of the discharge coefficient
change to be expected
a) Immediately downstream from a divergent taper piece
0,4 + 10
0,7 + 50
b) Immediately downstream from a convergent taper piece
0,4 − 0,5
0,7 2
c) Immediately upstream from a convergent taper piece
0 to − 1
0,7 + 1
6.6 Eccentricity

The requirements for concentric mounting of the device are given in, and 7.6.3 of ISO 5167-1 : 1991.

The geometric measure of eccentricity is the distance between the pipe and orifice plate centrelines and is often

expressed as a percentage of the pipe diameter D. Deviations from the permitted eccentricity values for the

mounting of an orifice plate relative to the upstream and downstream pipe sections will result in errors in the

measurement of flowrate. Figure 5 shows the eccentric mounting of an orifice plate in a sideways direction relative

to the upstream pipeline. The displacement is to the right and the eccentricity is a combination of the dimensional

tolerances arising from the bolt hole pitch circle diameter, the bolt diameter, the bolt hole diameter and the outer

diameter of the orifice plate.

Experimental evidence on the effects of eccentricity is limited, but it has been shown that for orifice plates, the effect

on discharge coefficient is a function of b, pipe size and roughness, pressure tapping type, location and magnitude,

as well as the position of the orifice centre relative to the pressure tapping.

Experimental work indicates that the errors due to eccentricity increase in general with b. For b = 0,2 and

eccentricity up to 5 % of D, discharge coefficient increases are unlikely to exceed 0,1 %. For larger b, the changes

are best shown graphically as in figure 6.

Below 3 % eccentricity, the error varies with type of taps and direction of eccentricity. The meter is least sensitive to

eccentricity perpendicular to the taps. Above 3 % eccentricity, errors for all taps and directions increase rapidly.

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ISO/TR 12767:1998(E)
Figure 3 — Carrier having internal diameter, D , less than pipe diameter, D
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ISO/TR 12767:1998(E)
Figure 4 — Effect of incorrect carrier diameter
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ISO/TR 12767:1998(E)

Figure 5 — Possible orifice plate eccentricity resulting from specified tolerances on bolt hole,

bolt hole pitch circle, pipe o.d. and flange bore

ISO 5167-1 requires an arithmetic increase in discharge coefficient uncertainty of 0,3 % if the eccentricity lies

0,0025D 0,005D
and (6)
01,, + 23 bb01,, + 23

NOTE No data are available for corner taps but the errors are probably similar to those for flange taps since the above

data were obtained from a test line with D = 150 mm.

A further effect of eccentric positioning of an orifice plate is an increased unsteadiness of the differential pressure

signal obtained. Observations have shown, for example, a marked increase in differential pressure reading

fluctuations with increasing eccentricity for all values of β between 0,4 and 0,7.

Because of the number of variants contributing to the effect of eccentricity on the measurement of flow, the effect is

difficult to quantify. Every effort should be made to restrict eccentricity to less than 3 % of D, particularly in the

direction of the taps.

The effect may be minimized by employing four equally-spaced upstream and downstream taps on the flowmeter,

as illustrated in figure 7. The pressure lines from these are then coupled in the widely used triple-T tapping

arrangement in order to obtain an average differential pressure reading.

As a general guide, it may be assumed that the effects of eccentric mounting for multi-tapped nozzles will be less

than those for orifice plates of equivalent β. Venturi tubes are less likely to be installed off-centre.

NOTE Combined installation faults: it is recommended that errors arising from the combined effects of eccentricity, carrier

ring steps etc. are not taken into account additively. The total possible error will be governed by the strongest of the effects

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ISO/TR 12767:1998(E)

Figure 6 — Discharge coefficient error vs. eccentricity for an orifice plate with D and D/2 and flange taps

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ISO/TR 12767:1998(E)
Figure 7 — Triple-T arrangements
7 Effects of pipe layout
7.1 General

Minimum values of the straight lengths required between the primary device and various upstream fittings are given

in 7.2 of ISO 5167-1 : 1991. Minimum straight lengths are given both for zero additional uncertainty and for 0,5 %

additional uncertainty in the discharge coefficient.

When the minimum requirements for even 0,5 % additional uncertainty cannot be satisfied, the user should make a

correction to compensate for the change in the discharge coefficient and should also increase the percentage

uncertainty in its value.

Corrections and additional uncertainties for square-edged orifice plate with corner, flange and D and D/2 tappings

are given in tables 3 and 4 for a variety of upstream pipe bends and fittings, respectively.

Additional data on shifts in orifice plate disharge coefficients for a large number of upstream fittings are given in

Martin C.N.B. [3]
7.2 Discharge coefficient compensation
7.2.1 Corrections

The discharge coefficient can be corrected using the data in table 3 as illustrated in the following examples:

a) percentage change in coefficient is +1,1 %, therefore the coefficient should be multiplied by 1,011;

b) percentage change in coefficient is -2,3 %, therefore the coefficient should be multiplied by 0,977.

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ISO/TR 12767:1998(E)

Table 3 — Percentage discharge coefficient changes (c) when the straight pipe lengths before the orifice

are less than those specified in ISO 5167-1
Upstream β Type of fitting (for details of nomenclature, see key)
1 2 3 4 5 6 7 8 9 1011 1213 1415 1617
4D 0,5 -1,4 -1,4 -0,5 +2,9 +2,9 -0,4 +8,2 +0,2 +0,2 -1,0 -0,8 +0,3 +0,5 +0,2
0,6 -2,3 -2,2 -1,1 +1,7 +1,3 -1,2 +8,5 -0,2 -0,3 -2,4 -1,7 +0,3 -0,2
0,7 -3,8 -3,2 -1,8 +0,1 +0,4 -2,1 +8,2 -0,9 -0,7 -4,4 -2,3 +0,3 -0,6 0
0,8 -5,6 -3,9 -2,6 -2,4 +0,5 -3,1 +3,4 -2,2 -0,2 -7,5 -1,0 +0,3 -1,3 +0,8
1) 1) 1)
8D 0,5 -0,3 +2,4 +2,4 0 +6,3 +6,4 -0,2 -0,2 -0,6 -0,4 -0,2 -0,2 -0,8 -0,7

0,6 -1,4 -1,2 -0,7 +1,4 +1,2 -0,7 +5,6 +6,1 -0,6 -0,4 -1,3 -1,2 -0,7 -0,8 -1,3 -1,2

0,7 -2,2 -1,9 -1,2 +0,3 +0,4 -1,3 +4,4 +6,1 -1,1 -0,8 -2,1 -1,9 +0,1 -1,2 -1,2 -1,7 -1,7

0,8 -3,2 -2,7 -1,8 -1,7 +0,4 -2,0 +2,3 +10,0 -1,9 -1,7 -3,1 -2,0 +0,1 -1,8 -1,0 -2,0 -2,1

1) 1) 1) 1)
12D 0,5 +2,0 +2,0 0 +5,5 +5,5 -0,2 -0,1 -0,4 -0,3 -0,3 -0,2
1) 1) 1)
0,6 -0,4 +1,2 +1,0 -0,4 +3,9 +4,3 -0,4 -0,3 -0,9 -0,9 -0,7 -0,6 -0,8 -0,8

0,7 -1,4 -1,4 -0,8 +0,3 +0,3 -0,8 +2,6 +3,2 -0,8 -0,7 -1,3 -1,3 -1,1 -1,0 -1,2 -1,1

0,8 -2,0 -2,0 -1,3 -1,3 +0,3 -1,3 +1,5 +6,8 -1,3 -1,4 -1,7 -1,6 -1,5 -1,2 -1,5 -1,4

1) 1) 1) 1)
16D 0,5 +1,7 +1,7 0 +5,1 +5,0 -0,1 0 -0,2 -0,2 -0,2 -0,2
1) 1) 1) 1)
0,6 +1,1 +0,9 -0,3 +3,5 +3,6 -0,3 -0,2 -0,6 -0,6 -0,4 -0,4
1) 1) 1)
0,7 -0,5 +0,3 +0,3 -0,5 +2,1 +2,4 -0,5 -0,5 -0,9 -1,0 -0,7 -0,6 -0,9
0,8 -1,3 -1,3 -0,7 -1,1 +0,3 -0,8 +0,8 +5,1 -0,8 -1,1 -1,0 -1,3 -1,0 -0,8 -1,2
1) Refer to table 3 of ISO 5167-1 : 1991.

Number Type of upstream fitting Type of taps Number Type of upstream fitting Type of taps

1 Single short radius 90° bend Corner, flange 10 Butterfly

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