1、STD.BSI BS EN 837-2-ENGL 1798 1bZLibbS Ob88117Li b3L BRITISH STANDARD Pressure gauges Part 2. Selection and installation recommendations for pressure gauges The European Standard EN 837-2 : 1997 has the status of a British Standard ICs 17.100 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY
2、COPYRIGHT LAW BS EN 837-2 : 1998 BS EN 837-2 : 1998 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standars Board and comes into effect on 15 March 1998 0 BSI 19% National foreword This British Standard i
3、s the English language version of EN 837-2 : 1997 published by the European Committee for Saneon (CEN). The UK participation in its preparation was entrusted by Technical Committee GEU5, Measurement and control, to Subcommittee GEY6512, Elements of systems, which has the responsibility to: - aid enq
4、uirers to understand the tea - present to the responsible European committee any enquiries on the inteqmtation, or proposals for change, and keep the UK interess hform - monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this
5、 subcommittee can be obtained on request to its secreiay. Cross-references “he British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled Intedona Standards Correspondence Index, or by u
6、sing the Find facility of the BSI Standards Electronic Catalogue. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 6, an inside back cover and a b
7、ack cover. Amendments issued since publication EUROPEAN sTANDAR;D NOFUME EUR0PEE”E EuRopAIscHE NOW EN 837-2 March 1997 ICs 17.100 Descriptors: Metrology, measuring instruments, pressure measurements, manometers, specifications, choice, storage, installation, maintenance English version Pressure gaug
8、es - Part 2: Selection and hstahtion TecoTnTnendations for pressure gauges Manomtres - Partje 2: Recommandations sur le choix et linstallation des manomtres Dniclunel3gerate - Ril2: Auswahl- und Einbauempfehlungen fr Druclunel3gert.e This European Standard was approved by CEN on 1997-0131. CEN membe
9、rs are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application
10、 to the Central Secretariat or to any CEN member. This European Standard ezricts in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the sa
11、me status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norwax Portugal, Spain, Sweden, Switzerland and United Kingdom. European Committee for S
12、tandardization Comit Europen de Normalisation Europisches Komitee fur Normung Central Secretariat: rue de Stassart 36, B-1060 Brussels O CEN 1997 AU rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 837-2 : 1997 E STD-BSI BS EN 837-2-ENGL 19
13、98 lb24bb9 Ob88477 3LiO 9 Page 2 EN 837-2 : 1997 Foreword This European Standard has been prepared by Thennometem - Means of measuring andor recording temperature during the distribution of refi-igemted, fiozen and quick-frozen products, the secretariat of which is held by AFNOR. This European Stand
14、ard shall be given the status of a nationai standard, either by publicaiion of an identical text or by endorsement, at the latest by September 1997, and conflicting nationai standads shall be withdrawn at the latest by September 1997. According to the CENKENELEC Internal Reguiations, the nationai st
15、andards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finiand, France, -, Greece, Iceland, Ireland, Ita - the respect of a certain number of rules and precautions concerning: . storage; . safety in view of the servi
16、ce conditions; installation; maintenance. steam Low High Polluted viscosity viscosity Bourdon tube 0,6 bar to 1600 bar X X 1) 1) 1 scope This European standard only applies to those pressure gauges whose pressure responsive element measuring system is a metal part which deforms under the effect of t
17、he pressure measured, as defined in EN 837-1 and This standard has been prepared to assist in the selection, instailation and use of pressure gauges to ensure that they give satisfactory service for the intended application with the maximum level of safety. EN 837-3. 2 Normative references This Euro
18、pean standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any these publications a
19、pply to this part of this European standard only when incorporated in it by amendment or revision. For undated references the atest edition of the publication referred to applies. EN 472 : 1994 EN 837-1 : 1996 Pressure gauges - Pressure gauges - Vocabulaw Part 1: Bourdon tube pressure gauges - Dimen
20、sions, metrology, requirements and testing Part 3: LXaphragm and capsule pasure gauges - Dimensions, metrology, requirements and testing EN 837-3 : 1996 Pressure gauges - Page 3 EN 837-2 : 1997 3 Definitions For the purpose of this European Standard the definitions given in EN 472 apply 4 Selection
21、Following criteria should be considered 4.1 Selection of pressure sensitive element The type of pressure responsive element may be selected according to the following table 1. 4.2 Safety 4.2.1 Pressure range The range should be such that the maximum working pressure does not exceed 75 % of the maxim
22、um scale value for steady pressure or 65 % of the maximum scale value for cyclic pressures. 4.2.2 Sqfetu design The safety design shall be selected in consideration of safety requirements of the specific applications. Criteria for the selection of pressure gauges with Bourdon tube are given in table
23、 2. For diaphragm and capsule gauges normally there are no specific requirements but the manufacturer should be consulted where special conditions may apply: for instance possibility of high pressure overload. NOTE. Capsule and diaphragm gauges are not recommended for oxygen and acetylene use. Howev
24、er, where absolutely necessary, consuitation between user and manufacturer is required. 4.3 Materials Pressure gauges are manufactured with pressure responsive elements that can be made from various materials. It is therefore necessary to choose from these materials the one best suited to the type o
25、f process fluid and its pressure. The purchaser shall indicate to the manufacturer all information concerning the materials which are compatible with the fluid in relation to the specific conditions of measurement. If none of the standard materials are suitable, it shall be necessary to interpose a
26、separator between the process fluid and the pressure gauge. The fliing of a chemical seal pressure gauge assembly shali always be done by the manufacturer and these two instruments shall never be uncoupled. I Table 1. I Reference of the - gauges with tapered threads: The pressure seai is normally ma
27、de by the mating of the thread, but it is common phce to apply jointing material to the male thread before assembly The jointing matern shal be compatible with the fluid (see figure lb); - diaphragm gauges with fiange connection should be fitted in accordance with recommendations from the relevant s
28、tandards; - direct mounting gauges should have the ghtenhg torque appiied to the connection by means of a spanner applied to the flats on the shank of the gauge. When tightening the pressure connection of a surface or flush mounted gauge, the tightening torque applied to the connection should be opp
29、osed by a spanner fitted to the flat on the shank of the gauge to prevent damaging the gauge or its mounting points. Do not tighten by grasping the case of the gauge as thismaycausedamage. When fitst applying pressure, the leak tightness of the connection shall be checked. All gauges shall be mounte
30、d verticaily unies marked on the dial (see EN 837-1 or EN 837-3). When the gauge incorporates a blow out device or blow-out back, a minimum distance of 20 mm hm any obstacle shali be ensured. O BSI 1998 STD-BSI BS EN 837-2-ENGL 1998 lb211bb7 06881180 735 Page 6 EN 837-2 : 1997 (1) Pressure joint sha
31、ii be made on this face oniy by means of the correct type sealing washer (2) Direct mounting Figure la. Parallel thread connections (3) Union nut and tailpipe connection (5) Pressure joint shail be made on the thread only. A suitable jointing material may be applied to the threads. (6) Direct mounti
32、ng flat bottom hole Figure lb. Taper thread connections Figure 1. Correct methods of making pressure connections (7) Direct mounting through hole (4) Compression fitting adaptor T+-r (8) Compressiong fitting adaptor O BSI 1998 Page 6 EN 837-2 : 1997 7.2 Special conditions 7.2.1 Mechanical shocks Pre
33、ssure gauges shall not be subject to mechanical shocks. If installations are subject to mechanical shocks, gauges shall be mounted remotely and connected by flexible pipe. 7.2.2 Vbrations When the actual support of the pressure gauge is subject to vibrations several solutions may be considered - use
34、 of liquid filled pressure gauges; - when vibrations are large de or random, it is preferable to proceed as for mechanical shocks, as defined in 7.2.1. The presence of vibrations may be detected by continuous oscillations, offen irreguiar, of the tip of the pointer. 7.2.3 Pressure pulses These are g
35、enerally present when pressure gauges are instaed on pumps. They are the cause of a considerable reduction of the life of the pressure responsive element and movement of the pressure gauge. They are generally indicated by the large amplitude of the pointer oscillations. It is necessary to reduce the
36、se pulses of pressure by interposing a damper between the pressure source and the pressure responsive element. 7.2.4 Overpressure Any overpm creates stress in the pressure responsive element and consequently reduces its life and accuracy It is therefore always preferable to use an instrument whose m
37、aximum de vahie is greater than the maximum working pressure and which will consequently absorb overpressure and surges more easily (see 4.2.1). Surges can be handled in the same way as pressure puises. Longer overpressum can be overcome by installing an overrange protection system. 7.2.5 lkmperatur
38、e 7.2.5.1 Ambiat temperacUre It is dicut to shield a pressure gauge from an ambient temperature that is too high or too low. One solution consists of moving the gauge away from the source of heat or cold when possible. A correction shali be applied when a gauge accuracy class 0,6 or better is used a
39、t an ambient temperatwe different from the reference temperature (20 “C f 2 OC). 7.2.6.2 Fluid ternpwatuw To protect a pressure gauge from a fluid which is too hot, a siphon or a similar device may be inserted so as to provide condensed fluid in the pressure responsive element. A siphon or a similar
40、 device shall always be placed close to the pressure gauge and be filled with condensate before the installation is presswised in order to avoid the hot fluid reaching the gauge on the initial pressurisation. The fluid in the pressure responsive element shall not be allowed to freeze or crystallize.
41、 When the temperature of the fluid cannot be modined, it is often necessary to insert a separator between the process fluid and the gauge provided the buffer fluid used is capable of withstanding the temperature of the process fluid 7.2.6 Cleanliness Certain applications require gauges which are pur
42、chased specially cleaned In such instance the user shall ensure that the instrument is correctly specified and instailed (for example: oxygen service pressure gauge oil free) 7.2.7 meet of liquid columns Theinstailershallbeawarethatifastaticheadof liquid is actjng on the gauge, it sha have been cali
43、brated accordingly and the compensation marked on the diai. 8 Putting into service An instabon shall always be brought into service carefully to avoid surges or sudden variations in temperature. Isolating valves shall therefore be opened slowly. 9 Maintenance The overall safety of an instalMon often
44、 depends on the operating condition of the pressure gauges it contains. It is essential that the measurements indicated by these gauges are reliable. Thus any pressure gauge whose indications appear to be abnormal shall be immmly removed, veried or recalibrated if nec-. Connnnation of gauge accuracy
45、 shoud be maintained by periodic testing. Verification and recaiibration sha be carried out by competent personnel using appropriate test equipment. O BSI 1998 STD-BSI BS EN 837-2-ENGL 1998 Lb24bb9 Ob88482 708 = BS EN 837-2 : 1998 BSI 389 Chiswick High Road London w4 4AL BSI - British Standards Inst
46、itution BSI is the independent nationai body responsible for preparing British standards. It presents the UK view on standards in Europe and at the intedonal level. It is incorporated by Royal Charter. Contract requirements A British Standard does not purport to include all the necessary provisions
47、of a contract Users of British standards are responsible for their correct application. Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quali
48、ty of our products and services. We would be gratefui if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretaqy of the responsible technical committee, the identity of which can be found on the inside front cover. Tek O181 996 9000; Fax O181 996 7400.
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