Table of Contents

Section one - General
0 Introduction
1 Scope
2 Symbols and definitions
3 Effect of errors on flowrate calculations
Section two - Effects of deviations in construction
4 Orifice plate edge sharpness
5 Thickness of orifice edge
6 Flatness of upstream face
7 Position of pressure tappings
8 Condition of pressure tappings
Section three - Effects of pipeline near the device
9 Pipe diameter
10 Steps and taper sections
11 Diameter of carrier ring
12 Undersize joint rings
13 Protruding welds
14 Eccentricity
Section four - Effects of pipe layout
15 General
16 Discharge coefficient compensation
17 Pressure tappings
18 Devices for improving flow conditions
Section five - Operational deviations
19 General
20 Buckling of an orifice plate
21 Deposition on the upstream face of an orifice
plate
22 Deposition in the meter tube
23 Deposition and increase of surface roughness
in venturi tubes
24 Orifice plate edge squareness
Section six - Pipe roughness
25 General
26 Upstream pipe
27 Downstream pipe
28 Reduction of roughness effects
29 Maintenance
Appendix
A Bibliography

Abstract

Provides guidance to assist in estimating the flow rate when using pressure differential devices constructed or operated outside the scope of Part 1.1. The information given permits users who may not be able to comply fully with the requirements to assess, however roughly, the magnitude and direction of the resulting errors. It is identical with and has been reproduced from BS 1042:Section 1.5:1987.

Scope

This Section of BS 1042 provides guidance to assist in estimating the flowrate when using pressure differential devices constructed or operated outside the scope of BS 1042 : Section 1.1.

It should not be implied that additional tolerances or corrections can necessarily compensate for the effects of deviating from the standard. The information is given, in the first place, to indicate the degree of care necessary in the manufacture, installation and maintenance of pressure difference devices by describing some of the effects of non-compliance with 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 errors.

Each variation dealt with is treated as though it were the only one present. but where more than one is known to exist, there will be interactions causing increases or decreases of error, largely unpredictable. This list of variations is by no means complete and relates largely to examples with orifice plates. There are, no doubt, many similar examples of installations not complying with BS 1042 : Section 1.1 for which no comparable data has been published. Such additional information from users, manufacturers and any others may be taken into account in future revisions of this Section of BS 1042.

NOTE. The titles of the publications referred to in this standard are listed on the inside back cover.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	Standards Australia
Pages
ISBN
Committee	CE-024