Sans 1062

ISBN 978-0-626-22299-4 SANS 1062:2010Edition 1.1

Any reference to SABS 1062 is deemedto be a reference to this standard

(Government Notice No. 1373 of 8 November 2002)

SOUTH AFRICAN NATIONAL STANDARD

Pressure and vacuum gauges

Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za © SABS

Copyright protected. This standard may only be used and printed by subscribers to the SABS’ Complete Collection of Standards and Related Documents in accordance with a formal copyright agreement.

SANS 1062:2010 Edition 1.1 Table of changes Change No. Date Scope

Amdt 1 2010 Amended to update the definition of “acceptable” and referenced standards, to change language requirements for the marking of dials, to update the quality verification appendix (appendix C), to delete a reference to the standardization mark, and to add a bibliography.

Foreword This South African standard was approved by National Committee SABS SC 138, Water and sanitation – Equipment and systems, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in February 2010. This document supersedes SABS 1062:1985 (first edition). A vertical line in the margin shows where the text has been technically modified by amendment No. 1.


SANS 1062:2010 Edition 1.1

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Contents

Page Foreword 1 Scope .................................................................................................................................. 3 2 Definitions ........................................................................................................................... 3 3 General and constructional requirements ............................................................................ 4 4 Performance requirements .................................................................................................. 13 5 Packing and marking ........................................................................................................... 14 6 Inspection and methods of test ............................................................................................ 15 6.1 Inspection ................................................................................................................... 15 6.2 Test conditions ........................................................................................................... 15 6.3 Accuracy test .............................................................................................................. 15 6.4 Overload test .............................................................................................................. 15 6.5 Pulsation test .............................................................................................................. 16 6.6 Leakage test ............................................................................................................... 16 6.7 Temperature stability test ............................................................................................ 16 Appendix A Applicable standards ......................................................................................... 17 Appendix B Notes to purchasers ........................................................................................... 17 Appendix C Quality verification of pressure and vacuum gauges .......................................... 19 Amdt 1 Appendix D Recommendations for the installation and use of gauges .................................. 21 Bibliography ........................................................................................................................... 22 Amdt 1



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Pressure and vacuum gauges 1 Scope 1.1 This specification covers circular analogue pressure gauges, vacuum gauges, and combined vacuum and pressure gauges (compound gauges) of nominal diameter in the range 40 mm ― 300 mm and that operate in the range 100 kPa below atmospheric pressure to 250 MPa above atmospheric pressure. The gauges covered are suitable for industrial and marine use with fluids such as air, water, oil, and steam, but provision is also made for gauges for use with other fluids. 1.2 This specification does not cover test gauges, gauges having dials with application bands only and gauges that do not use an elastic element to sense pressure. NOTE a) The standards referred to in the specification are listed in appendix A. b) Requirements that must be specified by the purchaser and those that must be agreed upon between the

manufacturer and the purchaser are listed in appendix B. c) Information regarding the verification of the quality of gauges produced to this specification, and a sampling

plan that could be used to assess compliance with the specification of a lot of gauges are given in appendix C.

d) Recommendations for the installation and use of gauges are given in appendix D. 2 Defnitions 2.1 For the purposes of this specification the following definitions shall apply: acceptable acceptable to the authority administering this standard, or to the parties concluding the purchase contract, as relevant Amdt 1 elastic element resilient element that converts a change in pressure or vacuum into motion gauge pressure, vacuum or compound gauge safety pattern gauge gauge designed exclusively to measure the pressure of one of the following: a) acetylene; b) oxygen;



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c) other oxidants; or d) any other gas where the pressure exceeds 6 MPa, and that incorporates constructional features so designed as to minimize the hazards inherent in the measurement of the pressure of such a gas 3 General and constructional requirements 3.1 General 3.1.1 Gauge type A gauge shall be of one of the following types: a) Compound gauge. A gauge that gives, by means of a single pointer relative to a scale, a visual

indication of the magnitude by which the pressure of a fluid applied to it exceeds or is less than the pressure of the surrounding atmosphere.

NOTE The scale of a compound gauge is continuous and reads zero at atmospheric pressure. b) Differential gauge. A gauge that has two pressure connections and a means to measure and

visually indicate the difference between the pressures applied at the two connections. c) Duplex gauge. A gauge that has two independent pressure connections and two independent

elastic elements, and a means to measure and visually indicate the two pressures applied at the two connections.

d) Pressure gauge. A gauge that gives, by means of a pointer relative to a scale, a visual

indication of the magnitude by which the pressure of a fluid applied to it exceeds the pressure of the surrounding atmosphere.

NOTE The scale of a pressure gauge is graduated to read zero at atmospheric pressure. e) Retarded scale gauge. A gauge that has a scale that is compressed at either or both ends. f) Suppressed scale gauge. A gauge that has a scale that commences at some value greater

than zero. g) Vacuum gauge. A gauge that gives, by means of a pointer relative to a scale, a visual indication

of the magnitude by which the pressure of a fluid applied to it is less than the pressure of the surrounding atmosphere.

NOTE The scale of a vacuum gauge is graduated to read zero at atmospheric pressure. 3.1.2 Gauge mounting The mounting of a gauge shall be of one of the following types (see figure 1): a) Direct mounting, where the gauge is supported by its screwed connection. NOTE The screwed connection may be located radially in or at the back of the gauge case. b) Panel mounting, where the gauge is supported by means of a flange at the front of the gauge

case so that the gauge is essentially flush with the panel. NOTE The screwed connection is generally at the back of the gauge case.



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a) Direct mounting, radial connection, no flange

b) Direct mounting, back connection, no flange

c) Surface mounting, radial connection, back flange

d) Surface mounting, back connection, back flange

e) Panel mounting, back connection, front flange

f) Panel mounting, radial connection, front flange

g) Panel mounting, back connection, clamp fixing, front flange

Figure 1 — Gauge mounting configurations



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c) Surface mounting, where the gauge is supported by means of a flange at the back of the gauge case so that the gauge projects forward from the panel.

NOTE The screwed connection is generally located radially in the gauge case. 3.1.3 Gauge size The size of a gauge, i.e. the nominal diameter of the case, shall be one of the following values: 40 mm; 50 mm; 63 mm; 80 mm; 100 mm; 125 mm; 150 mm; 200 mm; 250 mm; 300 mm. NOTE Gauges having diameters of 50 mm and 63 mm are international sizes for welding gauges. 3.1.4 Scale range A gauge (other than a retarded scale gauge or a suppressed scale gauge) shall have one of the scale ranges given in table 1. 3.1.5 Accuracy class A gauge shall be of one of the following accuracy classes (see 4.1): 0,6; 1,0; 1,6; 2,5. Pressure gauges used in welding, cutting and related processes shall be of accuracy class 2,5. 3.1.6 Durability grade A pressure gauge shall be of durability grade A, B or C (see 4.3). Pressure gauges used in welding, cutting and related processes shall be of durability grade C. 3.2 Materials NOTE The materials to be used in the case of the components covered in 3.2.1(b) – (d), 3.2.1(f) and 3.2.2(b) are subject to agreement between the manufacturer and the purchaser. 3.2.1 Gauges other than safety pattern gauges a) General. The materials used for the components of a gauge shall comply with the relevant

requirements given in (b) – (g) below. In the case of a gauge for use with a chemically active fluid other than acetylene, oxygen or other oxidants, the materials shall be so selected (see 3.2.2) as to withstand the corrosive action of that fluid.

b) Case and bezel ring. The case and the bezel ring shall be of one or a combination of the

following types of material: 1) reinforced plastics; 2) drawn sheet metal; 3) cast metal; 4) thermo-setting material.



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c) Elastic element. The elastic element shall be of one of the following types of material: 1) copper alloy; 2) alloy steel; 3) stainless steel; 4) nickel alloy; 5) nickel. d) Shank. Material used for the shank shall be compatible with that used for the elastic element. e) Pointer. The pointer shall be of a metal or other acceptable material. f) Window. The window shall be of sheet glass or other acceptable material, and shall be of

uniform thickness and free from defects. g) Dial. The material of the dial shall be such that the finished dial is capable of withstanding 1) a dry heat of 85 °C for 10 h; and 2) immersion in water at 85 °C for 1 h without cracking or blistering of the applied finish.

Table 1 — Scale ranges for gauges a) Vacuum gauges

1 2 3 4 5

Scale ranges Scale ranges Scale ranges Scale ranges Scale ranges

−10 Pa −16 Pa −25 Pa

to to to

0 0 0

−160 Pa −250 Pa −400 Pa

tototo

000

−2 500 Pa−4 000 Pa−6 000 Pa

tototo

000

−4kPa−6 kPa−10 kPa

tototo

000

−60 kPa −100 kPa

to to

00

−40 Pa −60 Pa −100 Pa

to to to

0 0 0

−600 Pa −1 000 Pa −1 600 Pa

tototo

000

−1 kPa−1,6 kPa−2,5 kPa

tototo

000

−16 kPa−25 kPa−40 kPa

tototo

000


1 2 3 4 5

Scale ranges Scale ranges Scale ranges Scale ranges Scale ranges

−400 Pa −600 Pa −600 Pa

to to to

600 Pa 400 Pa

1 000 Pa

−1,5 kPa−2 kPa

−2,5 kPa

tototo

2,5 kPa4 kPa

1,5 kPa


tototo

10 kPa6 kPa

15 kPa

−20 kPa −40 kPa −40 kPa

to to to

40 kPa20 kPa60 kPa

−100 kPa−100 kPa−100 kPa

to to to

150 kPa300 kPa500 kPa

−1 000 Pa −1 kPa

−1,5 kPa

to to to

600 Pa 1,5 kPa

1 kPa


tototo

2 kPa6 kPa4 kPa


tototo

10 kPa25 kPa15 kPa

−60 kPa −60 kPa −100 kPa

to to to

40 kPa100 kPa60 kPa

−100 kPa−100 kPa−100 kPa

to to to

900 kPa1 500 kPa2 400 kPa

b) Com

pound gauges

8 SAN

S 1062:2010 E

dition 1.1



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c) Pressure gauges

1 2 3 4

Scale ranges Scale ranges Scale ranges Scale ranges

0 0 0

to to to

10 Pa 16 Pa 25 Pa

0 0 0

tototo

2 500 Pa4 000 Pa6 000 Pa

000

to to to


000

tototo

1,6 MPa 2,5 MPa

4 MPa 0 0 0

to to to

40 Pa 60 Pa

100 Pa

0 0 0

tototo

1 kPa1,6 kPa2,5 kPa

000

to to to


000

tototo

6 MPa 10 MPa 16 MPa

0 0 0

to to to

160 Pa 250 Pa 400 Pa

0 0 0

tototo

4 kPa6 kPa

10 kPa

000

to to to

1 000 kPa1 600 kPa2 500 kPa

000

tototo

25 MPa 40 MPa 60 MPa

0 0 0

to to to

600 Pa 1 000 Pa 1 600 Pa

0 0 0

tototo

16 kPa25 kPa40 kPa

000

to to to

4 000 kPa6 000 kPa

1 MPa

000

tototo

100 MPa 160 MPa 250 MPa

3.2.2 Safety pattern gauges a) General. The requirements given in 3.2.1 shall apply, with the following differences: b) Elastic element 1) in the case of a gauge for use with acetylene, components that come into contact with the gas

shall be of stainless steel or pure nickel. For welding gauges, the use of a copper alloy containing not more than 65 % (m/m) copper may be used;

2) gauges for use with oxygen and other oxidants shall be free from oil and grease; and 3) the elastic element of welding gauges shall be capable of withstanding for 1 min a pressure of

50 % above that of the maximum scale value, without visible damage. c) Window. The window of a safety pattern gauge shall be of safety glass or clear plastics material,

and shall be of uniform thickness and free from defects. 3.3 Construction NOTE The requirements given in 3.3.1(b)(1), 3.3.1(b)(3) and 3.3.1(c)(4) are subject to agreement between the manufacturer and the purchaser. 3.3.1 Gauges other than safety pattern gauges a) General. Any joint that may allow entry of dust or fumes into the interior of a gauge shall

preferably be effectively sealed (see also figure 2). b) Case and bezel ring 1) The case shall have either an open front or a baffle wall (a safety barrier between the elastic

element and the dial). 2) The bezel ring shall be of the threaded, bayonet, hinged, screw-fixing, crimped or snap

pattern. 3) The case and bezel ring shall have the finish agreed upon between the manufacturer and the

purchaser.



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NOTE C-shaped tubular elastic element illustrated. Other common types of elastic elements are coiled and spiral tubes, bellowes, capsules and diaphragms.

Figure 2 — Component parts of a gauge



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c) Shank 1) The shank shall have been stamped, or machined from bar stock, and shall incorporate a

hexagon, a square or parallel flats. 2) The dimensions of the shank shall conform to the values given in table 2, appropriate to the

size of the screwed connection. Screw threads shall preferably conform to the relevant requirements of SANS 1109-1 or SANS 1306-1. Amdt 1

3) The seating shall be flat, and may have one or more concentric grooves cut in its face. 4) A gauge that is used to measure the pressure of a chemically active fluid that could have a

corrosive effect on material(s) used in the construction of the internal parts of the gauge shall have a seal of a material that is resistant to the fluid fitted to the shank.

d) Elastic tube and tube anchorage 1) The tube anchorage shall have been stamped, or machined from bar stock. It shall be either

integral with the shank or connected to it by means of a pressure-conducting system. 2) Particular attention shall be given to the attachment of the elastic tube to the tube anchorage,

and to the fitting of the tube end piece. 3) The joints between the elastic tube and the tube anchorage and between the tube end piece

and the elastic tube, and any other joint in the pressure-conducting system, shall be made by soft-soldering, brazing or welding.

4) Where a gauge is intended to be used with a chemically active fluid, soldering, brazing or

welding metal used shall be such that it withstands the action of the fluid. 5) Silver brazing shall not be used as a joint material for gauges that are used with acetylene. e) Movement. The movement shall be of a geared type and it shall be so mounted on the

anchorage, or on any other part of the gauge that is integral with the anchorage, that there can be no motion between the parts.

NOTE In order to reduce wear of the movement in conditions of abnormal vibration or pulsation, a gauge

may be filled with an acceptable liquid, or the movement may be made of wear-resistant materials, or both. f) Pointer and pointer stop. The length of the pointer shall be at least 75 % of the radius of the

dial. The tip of the pointer shall be as near to the dial as is practicable, and shall lie within the ends of the shorter graduation lines. The width of the pointer tip shall be such that the gauge can be read to a value within the accuracy of the scale.

The pointer shall be securely fixed to its spindle, and a pointer stop shall preferably be provided. g) Dial and scale 1) The scale shall extend over an arc of approximately 270°. The scale marking shall preferably

be black on a matt white background. Where a particular pressure is to be emphasized, this indication shall take the form of a distinctive coloured line on the scale. Graduations shall be at multiples of 2; 5 or 10 scale units. The maximum and minimum scale values shall preferably be at the bottom of the dial, and the scales shall normally be symmetrically disposed about the vertical centre-line of the dial.



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2) Scale values shall increase in a clockwise direction, corresponding to an increase in pressure. Any increase in vacuum shall preferably be indicated in an anti-clockwise direction. Scales shall preferably not have boundary lines, and the scale markings shall not be obscured by the bezel ring.

3) The symbol of the scale unit and, when this is not unity, the scale factor, shall be clearly

marked on the dial, the scale unit being located immediately above the scale factor (see 5.2.1(b)).

NOTE In the field of welding when more than one gauge is fitted to a pressure regulator and the

connections are such that it is physically possible to interchange the positions of the gauges, both gauges should have the pressure indicated in the same units without the use of a scale factor.

Table 2 — Dimensions of shank

NOTE a) A shank with parallel thread shown. b) A spigot is omitted from a shank with a taper thread.

Dimensions in millimetres

1 2 3 4 5 6

Length of hexagon, square or

flats

Length of parallel thread

Length of taper

thread Length of

spigot

Nominal diameter of

spigot

l3 l2 l2 l1 d

Size of screwed

connection

min. min. min. max. 6 8

10 15

4,5 6

10 12

9,5 13 16 20

10 11 14 16

4 4 5 5

4 5 5,5 6



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3.3.2 Safety pattern gauges a) General. Except as required in terms of (b) – (d) below, the construction of a safety pattern

gauge shall be as specified in 3.3.1. b) Case. A baffle wall shall be interposed between the elastic element and the dial, and a blow-out

device of adequate size shall be fitted to the back of the gauge case to permit the rapid and safe dissipation of internal pressure in the event of rupture of the elastic element.

c) Shanks. A restrictor having a cross-sectional area not exceeding 0,1 mm2 shall be fitted in the

shank. d) Dial. The following information, clearly marked in at least English, shall appear on the dial of

each gauge for use with Amdt1 1) acetylene: the word "Acetylene" in red letters; 2) oxygen: the word "Oxygen" in blue letters and the words "No oil" or the international "No oil"

pictogram; 3) other oxidants (e.g. nitrous oxide): the name of the gas in black letters and the words "No oil"

or the international "No oil" pictogram; 4) medical and industrial gases: the name of the gas in black letters and the words "No oil" or

the international "No oil" pictogram. 4 Performance requirements 4.1 Accuracy When a gauge is tested in accordance with 6.3, any error in pressure indication at any position on the scale shall not exceed the appropriate value given in column 2 of table 3. NOTE The indication error is expressed as a percentage of the span (i.e. the algebraic difference between the maximum and minimum scale values) of the gauge.

Table 3 — Gauge accuracy

1 2

Indication error % Accuracy class*

max.

0,6 1,0 1,6 2,5

0,5 0,8 1,3 2,0

* Refers to service conditions. 4.2 Overload a) When a pressure or compound gauge (other than a gauge used for welding and related

processes) is tested in accordance with 6.4, the elastic element shall withstand the overload pressure, and



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b) at the end of the test, the gauge shall still comply with the accuracy requirements given in 4.1. 4.3 Durability After having been tested in accordance with 6.5, a gauge a) shall be free from visible damage to the movement; and b) after zero adjustment, shall still comply with the accuracy requirements given in 4.1. 4.4 Leakage When a gauge is tested in accordance with 6.6, the pressure indicated by the gauge shall remain constant for the duration of the test. 4.5 Temperature stability After having been tested in accordance with 6.7, a gauge shall still comply with the accuracy requirements given in 4.1. 5 Packing and marking 5.1 Packing Each gauge shall be so packed in a container that the screwed connection and inlet orifice of the gauge are protected from damage to the thread and from the ingress of foreign matter. 5.2 Marking 5.2.1 Gauges Each gauge shall bear the following information, legibly and indelibly marked on the dial: a) the manufacturer's name or trade name or trademark; b) the symbol of the scale unit and the scale factor when other than unity; c) the accuracy class when of class 1,0 or 0,6; d) the information given in 3.3.2(d) relevant to the type of gas with which the gauge is intended to

be used; e) when relevant, the correction for a positive or negative static head. NOTE Any other marking shall be unobtrusive and shall preferably be outside the area swept by the pointer. 5.2.2 Containers Each container shall bear the following information: a) the nominal size of the gauge, in millimetres; b) the scale range and scale unit of the gauge; c) the accuracy class of the gauge.



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6 Inspection and methods of test 6.1 Inspection Visually examine and measure each gauge in the sample for compliance with all the relevant requirements of the specification for which tests to assess compliance are not given in 6.3 – 6.7 (inclusive). 6.2 Test conditions Except in the case of the test given in 6.7, maintain each gauge under test at an ambient temperature of 20 ± 2 °C, and with the dial in an upright vertical position. 6.3 Accuracy test 6.3.1 Apparatus A mercury manometer, laboratory test gauge or dead-weight tester, as appropriate, that is at least four times as accurate as the gauge under test and that is connected to a pump system capable of producing a full scale reading on the gauge under test. 6.3.2 Procedure a) Connect the gauge under test to the test apparatus; b) vary the pressure of the system from that producing a zero reading to that producing a full scale

reading on the gauge under test, and record, at five points uniformly distributed over the scale, the error in the pressure indicated by the gauge;

c) repeat the procedure given in (b) above, but vary the pressure from that giving a full scale

reading to that giving a zero reading. (At each point, lightly tap the case of the gauge under test before recording the error);

d) check for compliance with the requirements of 4.1. 6.4 Overload test 6.4.1 Apparatus Use the apparatus given in 6.3.1 above, except that the pump system shall be capable of producing the pressure given in table 4, relevant to the maximum scale value of the gauge under test. 6.4.2 Procedure a) Connect the gauge under test to the test apparatus, and increase the pressure to the value given

in column 2 of table 4, relevant to the maximum scale value of the gauge. b) Maintain the pressure at this value for not less than 15 min and check for compliance with the

requirement of 4.2(a). c) Repeat the test given in 6.3 above, and check for compliance with the requirement of 4.2(b).



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Table 4 — Overload test pressures

1 2 Maximum scale value of gauge Test pressure

MPa % of maximum scale value Up to 10 ............................................From 16 to 60 ...................................From 100 to 160 ...............................250 ....................................................

125 115 110 105

6.5 Pulsation test 6.5.1 Apparatus Any suitable apparatus capable of applying a pressure that varies, at a rate of 1 Hz, between 30 ± 5 % and 70 ± 5 % of the maximum scale value of the gauge under test. 6.5.2 Procedure a) Subject the gauge under test to the appropriate number of pulsations given in table 5, relevant to

the grade of the gauge. b) Check for compliance with the requirement of 4.3(a). c) Repeat the test given in 6.3 and check for compliance with the requirement of 4.3(b).

Table 5 — Pulsation test

1 2 Durability grade

of gauge Number of pulsations

A B C

250 000 125 000 25 000

6.6 Leakage test Using a suitable pump system a) apply to the gauge under test a pressure of at least 80 % of its full scale value (or greater for

gauges intended for special applications requiring greater leakage integrity); b) maintain the pressure at this level for at least 30 min (or longer for gauges intended for special

applications), whilst checking for compliance with the requirements of 4.4. 6.7 Temperature stability test a) Subject the gauge under test to the following temperatures: 1) −20 °C for 6 h, then 2) 50 °C for 6 h. Repeat the test given in 6.3 and check for compliance with the requirements of 4.5.



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Appendix A

Applicable standards Reference is made to the latest issues of the following standards: SANS 1109-1/ISO 7-1, Pipe threads where pressure-tight joints are made on the threads – Part 1: Dimensions, tolerances and designation. Amdt 1 SANS 1306-1/ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads – Part 1: Dimensions, tolerances and designation. Amdt 1

Appendix B

Notes to purchasers B.1 The following requirements must be specified in tender invitations and in each order or contract: a) The gauge type (see 3.1.1) b) The gauge mounting (see 3.1.2) c) The gauge size (see 3.1.3) d) When relevant, the scale range of the gauge (see 3.1.4) e) The accuracy class of the gauge (see 3.1.5) f) The durability grade of the gauge (see 3.1.6) g) Whether a dust and fume proof case is required (see 3.3.1(a)) h) The type and size of screwed connection (see 3.3.1(c)(2)) B.2 The following requirements must be agreed upon between the manufacturer and the purchaser: a) The material of the case and bezel ring (see 3.2.1(b)) b) The material of the elastic element (see 3.2.1(c)) c) The material of the shank (see 3.2.1(d)) d) The material of the window (see 3.2.1(f)) e) The material of the components of safety pattern gauges for use with acetylene (see 3.2.2(b)) f) Whether an open front or a baffle wall case is required (see 3.3.1(b)(1))



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g) The finish of the case and bezel ring (see 3.3.1(b)(3)) h) Whether a seal fitted to the shank is required (see 3.3.1(c)(4)) i) Whether liquid filling or wear-resistant materials or both are required (see 3.3.1(e) NOTE) j) The leakage rate of a gauge required for special applications (see 4.4) B.3 The following additional information should be submitted to the manufacturer to assist in the selection of the correct type of gauge: a) The form of the equipment to which the gauge will be fitted, i.e. whether 1) stationary, 2) mobile, or 3) portable b) Any adverse condition such as exposure of the gauge to a corrosive atmosphere, extreme heat

or cold, or high humidity c) Whether the gauge will be subject to shock loading d) Whether the gauge will be subject to mechanical vibration or mechanical shock or both e) The static head acting on the gauge f) The temperature of the fluid g) Whether the gauge is to be used in a position other than upright and vertical



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Appendix C Quality verification of pressure and vacuum gauges Amdt 1 C.1 Quality verification C.1.1 When a purchaser requires ongoing verification of the quality of pressure and vacuum gauges, it is suggested that, instead of concentrating solely on evaluation of the final product, he also direct his attention to the manufacturer’s quality system. In this connection it should be noted that SANS 9001 covers the provisions of an integrated quality management system. Amdt 1 C.1.2 If no information about the implementation of quality control or testing during manufacture is available to help in assessing the quality of a lot, and a purchaser wishes to establish by inspection and testing of samples of the final product whether a lot (as defined in C.2.1) of the gauges produced to this specification complies with its requirements, the sampling plan given in C.2 and based on the stated AQLs can be applied. (If a different AQL is required, reference should be made to applicable statistical sampling tables.) Amdt 1 It must be noted that a) such a sampling plan applies to fully manufactured produts only; and b) a lot that in terms of the plan is deemed to comply with the specification, could contain defective

gauges to an extent proportional to that permitted by the relevant acceptance numbers given in the sampling table.

C.2 Assessment of compliance with the specification C.2.1 Definitions acceptable quality level AQL maximum percentage defective that for the purpose of sampling inspection can be considered satisfactory as a process average defective gauge that fails in one or more respects to comply with the relevant requirements of the specification lot not more than 1 200 gauges of the same size, type, durability grade and accuracy class, from one manufacturer, submitted at any one time for inspection and testing C.2.2 Sampling Use the following sampling procedure to determine whether a lot complies with the specification, and deem the samples so taken to represent the lot for the respective properties: a) Sample for inspection From the lot take at random the number of gauges shown in column 2 of table C.1 relative to the

appropriate lot size shown in column 1.



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b) Sample for testing After inspection of the sample taken in accordance with (a) above, take from it at random the

appropriate number of gauges shown in column 4 of table C.1.

Table C.1 — Sample sizes

1 2 3 4

Sample for inspection* Lot size Sample size

Sample for testing

gauges gauges Acceptance number

(AQL = 2,5) gauges 2

26 51

91

151 281 501

– – – – – – –

25 50 90

150 280 500

1 200

5+ 5

20

20 32 50 80

0 0 1 1 2 3 5

1 2 2 3 3 3 3

* Based on table II-A of BS 6001-1 + If the sample size equals or exceeds the lot size, do a 100 % inspection.

Amdt 1 C.3 Criteria of compliance Deem the lot to comply with the requirements of the specification if a) on inspection of the sample taken in accordance with C.2.2(a), the number of defectives found

does not exceed the relevant acceptance number given in column 3 of table C.1; and b) on testing of the sample taken in accordance with C.2.2(b), no defective is found.



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Appendix D

Recommendations for the installation and use of gauges D.1 General a) The maximum scale value of a gauge should be so chosen as to be approximately twice the

normal operating pressure of the gauge. b) When a pressure gauge is being installed, care should be taken to ensure that the joint is leak-

free and that there is no strain on the gauge in the installed position. c) To facilitate replacement, provision should also be made to isolate the gauge by means of a cock

or valve. Gauge cocks or valves should be opened slowly to avoid sudden loading of the gauge. d) Gauges should be so installed that they are not subjected without protection to excessive heat or

cold or to excessive vibrations or line pulsations. (Gauges subjected to these conditions cannot be expected to give optimum performance with respect to either accuracy or life.)

e) Pressure gauges should not be subjected to pressures in excess of the maximum scale value,

and vacuum gauges should not be subjected to pressure. D.2 Methods of making a joint D.2.1 Direct-mounting gauges For gauges with parallel threads, the only correct position for the joint is on the flat seating around the spigot. A corresponding flat seating is required on the mating fitting. Incorrect methods include attempting to make the joint on the threads by the use of sealing compounds such as hemp, red lead, etc., or on the end of the spigot, or by the use of back nuts. One sealing washer of the correct size and material should be used in making the joint and enough thread engagement must be achieved to avoid blow-outs. For gauges with tapered threads, the seal is made on the threads, using one turn of a PTFE tape (or other suitable sealant) and leaving the leading thread uncovered to avoid pieces of tape entering the pressure system. Tape used for sealing joints of gauges for use with oxygen and other oxidant gases must be oil-free. Gauges should be tightened by means of the hexagon or square provided, and not by grasping the case of the instrument. D.2.2 Surface and panel-mounting gauges In order to avoid any strain on the gauge, the connecting pipes to a surface or panel-mounted gauge should be flexible, particularly where excessive expansion and contraction of the pipe takes place due to changes in temperature. If rigid piping is used, a loop or coil in the pipe may provide the required flexibility. D.3 Gauges for steam It is essential that steam be prevented from entering the elastic element. Protection may be effected by interposing a siphon between the gauge and the line. The siphon may be an independent fitting formed from copper or stainless steel tubing and bent to form a 180° loop in its length, or may similarly be formed in the run of piping to the gauge. The siphon should be filled with water before the gauge is put into service.



22

D.4 Temperature protection Gauges exposed to excessive heat or cold may cause indication errors, and they should therefore not be mounted on hot boiler casings or hot machine parts. If a gauge cannot be grasped by hand without discomfort, it is at too high a temperature. When exposed to very low temperatures, elastic elements that contain water may burst. D.5 Position of gauge Gauges should be installed with the dial in an upright vertical position as, if it is mounted in other positions, the mass of the working parts may influence the reading. It is therefore necessary to advise the manufacturer when a gauge is to be mounted in some other position so that the gauge may be suitably calibrated. D.6 Gauges with a blow-out device Gauges with a blow-out back should be so mounted that there are no obstructions closer than one gauge diameter from the blow-out device of the gauge. D.7 Effect of static heads When a static head of liquid will act on the gauge, the manufacturer should be advised of this fact by the purchaser as allowance should be made for this at the time of calibration of the gauge. D.8 Rapidly fluctuating pressures, shock pressures and vibration Gauges should not be used under any of the following conditions: a) Where the pressure fluctuates at the rate of more than 1 Hz. NOTE Pressure oscillations of high frequency produce a destructive pressure ripple. These often originate

in hydraulic pumps and chattering relief valves. b) Where pressure is applied or released so rapidly as to produce shock or heating (which often

occurs in hydraulic presses and hydraulic tests). c) Where mechanical vibration is transmitted to the gauge through either the piping or the mounting. It is possible to provide protection for the gauge under some of these conditions, and the gauge manufacturer should be consulted in this regard. Bibliography Amdt 1 BS 6001-1, Sampling procedures for inspection by attributes – Sampling schemes indexed by acceptable quality limit (AQL) for lot-by-lot inspection. Amdt 1 SANS 9001/ISO 9001, Quality management systems – Requirements. Amdt 1

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SABS – Standards Division The objective of the SABS Standards Division is to develop, promote and maintain South African National Standards. This objective is incorporated in the Standards Act, 2008 (Act No. 8 of 2008). Amendments and Revisions South African National Standards are updated by amendment or revision. Users of South African National Standards should ensure that they possess the latest amendments or editions. The SABS continuously strives to improve the quality of its products and services and would therefore be grateful if anyone finding an inaccuracy or ambiguity while using this standard would inform the secretary of the technical committee responsible, the identity of which can be found in the foreword. Tel: +27 (0) 12 428 6666 Fax: +27 (0) 12 428 6928 The SABS offers an individual notification service, which ensures that subscribers automatically receive notification regarding amendments and revisions to South African National Standards. Tel: +27 (0) 12 428 6883 Fax: +27 (0) 12 428 6928 E-mail: [email protected] Buying Standards Contact the Sales Office for South African and international standards, which are available in both electronic and hardcopy format. Tel: +27 (0) 12 428 6883 Fax: +27 (0) 12 428 6928 E-mail: [email protected] South African National Standards are also available online from the SABS website http://www.sabs.co.za Information on Standards The Standards Information Centre provides a wide range of standards-related information on both national and international standards, and is the official WTO/TBT enquiry point for South Africa. The Centre also offers an individual updating service called INFOPLUS, which ensures that subscribers automatically receive notification regarding amendments to, and revisions of, international standards. Tel: +27 (0) 12 428 6666 Fax: +27 (0) 12 428 6928 E-mail: [email protected] Copyright The copyright in a South African National Standard or any other publication published by the SABS Standards Division vests in the SABS. Unless exemption has been granted, no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means without prior written permission from the SABS Standards Division. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any purpose other than implementation, prior written permission must be obtained. Details and advice can be obtained from the Senior Manager. Tel: +27 (0) 12 428 6666 Fax: +27 (0) 12 428 6928 E-mail: [email protected]


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