BS EN 837-2-1998 Pressure gauges - Selection and installation recommendations for pressure gauges《压力计 压力计的选择和安装推荐规范》.pdf

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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 837-2 : 1998 The Eu

2、ropean Standard EN 837-2 : 1997 has the status of a British Standard ICS 17.100 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Pressure gauges Part 2. Selection and installation recommendations for pressure gaugesThis British Standard, having been prepared under the direction

3、 of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 March 1998 BSI 1998 ISBN 0 580 28894 3 BS EN 837-2 : 1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English

4、 language version of EN 837-2 : 1997 published by the European Committee for Standardization (CEN). The UK participation in its preparation was entrusted by Technical Committee GEL/65, Measurement and control, to Subcommittee GEL/65/2, Elements of systems, which has the responsibility to: aid enquir

5、ers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on th

6、is subcommittee can be obtained on request to its secretary. Cross-references The 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 International Standards Correspondence Index,

7、 or by using 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

8、 and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels CEN 1997 All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref

9、. No. EN 837-2 : 1997 E EUROPEAN STANDARD EN 837-2 NORME EUROPE ENNE EUROPA ISCHE NORM March 1997 ICS 17.100 Descriptors: Metrology, measuring instruments, pressure measurements, manometers, specifications, choice, storage, installation, maintenance English version Pressure gauges Part 2: Selection

10、and installation recommendations for pressure gauges Manome tres Partie 2: Recommandations sur le choix et linstallation des manome tres Druckmegera te Teil 2: Auswahl- und Einbauempfehlungen fu r Druckmegera te This European Standard was approved by CEN on 1997-01-31. CEN members are bound to compl

11、y with the CEN/CENELEC 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 to the Central Secr

12、etariat or to any CEN member. This European Standard exists 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 same status as the offi

13、cial versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 837-2 : 1997 BSI 1998 Foreword This

14、 European Standard has been prepared by Technical Committee CEN/TC 141, Pressure gauges Thermometers Means of measuring and/or recording temperature during the distribution of refrigerated, frozen and quick-frozen products, the secretariat of which is held by AFNOR. This European Standard shall be g

15、iven the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 1997, and conflicting national standards shall be withdrawn at the latest by September 1997. According to the CEN/CENELEC Internal Regulations, the national standards orga

16、nizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. This European standa

17、rd consists of the following parts, under the general title Pressure gauges: Part 1 : Bourdon tube pressure gauges Dimensions, metrology, requirements and testing Part 2 : Selection and installation recommendations for pressure gauges Part 3 : Diaphragm and capsule pressure gauges Dimensions, metrol

18、ogy, requirements and testing. Contents Page Foreword 2 0 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Selection 3 5 Transport 4 6 Storage prior to installation 4 7 Installation 4 8 Putting into service 6 9 Maintenance 6Page 3 EN 837-2 : 1997 BSI 1998 Table 1. Reference of the

19、 standard Type of pressure gauge Pressure range Process fluid Gas or steam Liquid Low viscosity High viscosity Polluted EN 837-1 Bourdon tube 0,6 bar to 1600 bar x x 1) 1) EN 837-3 Diaphragm 2,5 mbar to 25 bar xxxx EN 837-3 Capsule 1 mbar to 600 mbar x x 2) 1) Separators should be used. 2) The capsu

20、le and the pipe shall be fully filled with the liquid. 0 Introduction Pressure gauges are instruments used for pressure measurement which implies: the selection of a gauge suited to the conditions of use; the respect of a certain number of rules and precautions concerning: storage; installation; saf

21、ety in view of the service conditions; maintenance. 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 the pressure measured, as defined in EN 837-1 and EN 837-3. This standard has

22、been prepared to assist in the selection, installation and use of pressure gauges to ensure that they give satisfactory service for the intended application with the maximum level of safety. 2 Normative references This European standard incorporates, by dated or undated reference, provisions from ot

23、her 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 apply to this part of this European standard only when incorporated in it by a

24、mendment or revision. For undated references the latest edition of the publication referred to applies. EN 472 : 1994 Pressure gauges Vocabulary EN 837-1 : 1996 Pressure gauges Part 1: Bourdon tube pressure gauges Dimensions, metrology, requirements and testing EN 837-3 : 1996 Pressure gauges Part 3

25、: Diaphragm and capsule pressure gauges Dimensions, metrology, requirements and testing 3 Definitions For the purpose of this European Standard the definitions given in EN 472 apply. 4 Selection Following criteria should be considered: 4.1 Selection of pressure sensitive element The type of pressure

26、 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 maximum scale value for steady pressure or 65 % of the maximum scale value for cyclic pressures. 4.2.2 Safety

27、 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 2. For diaphragm and capsule gauges normally there are no specific requirements but the manufacturer sh

28、ould 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. However, where absolutely necessary, consultation between user and manufacturer is required. 4.3 Materials Pr

29、essure 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 of process fluid and its pressure. The purchaser shall indicate to the manufacturer all information conce

30、rning 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 separator between the process fluid and the pressure gauge. The filling of a chemical seal pressure gaug

31、e assembly shall always be done by the manufacturer and these two instruments shall never be uncoupled.Page 4 EN 837-2 : 1997 BSI 1998 Table 2. Criteria for selection of pressure gauges with Bourdon tube (safety aspect) Pressure fluid Liquid Gas or steam (see note 1) Case filling Dry Liquid Dry Liqu

32、id Nominal size25 # 25 25 # 25 25 # 25 25 # 25 25 # 25 25 # 25 25 # 25 25 Minimum safety design code 0000S 1S 1S 1S 10S 2S 1S 3S 1S 2S 1S 3 Safety design codes : 0 Gauge without blow-out device S1 Blow-out device gauge S2 Safety pattern gauge without baffle wall S3 Safety pattern gauge with baffle w

33、all (providing a higher level of safety) NOTE 1. All oxygen and acetylene gauges shall be safety pattern gauges. NOTE 2. Glycerine filled gauges shall not be used with oxygen or other strong oxidizing process fluid. For such applications, highly fluorinated and chlorinated liquids can be used. NOTE

34、3. This table indicates the normal safety design code. Users must have cognizance of their special requirements and may use safety pattern gauges at pressures lower than 25 bar. 4.4 Accuracy The accuracy class required shall be selected from EN 837-1 or EN 837-3. 4.5 Pressure connection The pressure

35、 connection shall be selected from EN 837-1 or EN 837-3. Other connections specific to certain industries and applications shall be specified. 4.6 Nominal size The size of gauge required shall be selected from EN 837-1 or EN 837-3. 4.7 Mounting Type of mounting required shall be selected from EN 837

36、-1 or EN 837-3. 4.8 Other criteria If the application involves pressure pulsations, vibrations, extremes of temperature, shock loading, solids in suspension, viscous or chemically aggressive pressure fluid, hostile environment, or requires correction for a static head, the manufacturer shall be cons

37、ulted. 5 Transport Certain modes of transport may be incompatible with certain types of pressure gauges (for instance: high precision gauges or gauges with sensitivity to variations of atmospheric pressure). In these cases, the customer shall leave the manufacturer with free choice of the means of t

38、ransport, even the free choice of the carrier. 6 Storage prior to installation Gauges should be stored in dry, clean conditions within the temperature range of2408C to +708C and protected against any impact damage. 7 Installation 7.1 General The user shall ensure that the correct gauge has been sele

39、cted and has the correct range and construction. If necessary an isolating valve shall be inserted to facilitate removal for maintenance. Pressure connections shall be leak tight: gauges with parallel threads: The pressure seal is made on the sealing face using a sealing washer which is compatible w

40、ith the fluid (see figure 1a); gauges with tapered threads: The pressure seal is normally made by the mating of the thread, but it is common practice to apply jointing material to the male thread before assembly. The jointing material shall be compatible with the fluid (see figure 1b); diaphragm gau

41、ges with flange connection should be fitted in accordance with recommendations from the relevant standards; direct mounting gauges should have the tightening torque applied to the connection by means of a spanner applied to the flats on the shank of the gauge. When tightening the pressure connection

42、 of a surface or flush mounted gauge, the tightening torque applied to the connection should be opposed 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 this may cause damage. When firs

43、t applying pressure, the leak tightness of the connection shall be checked. All gauges shall be mounted vertically unless 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 from any obstacle shall be ensured.Page

44、 5 EN 837-2 : 1997 BSI 1998 (1) Pressure joint shall be made on this face only by means of the correct type sealing washer (2) Direct mounting (3) Union nut and tailpipe connection (4) Compression fitting adaptor Figure 1a. Parallel thread connections (5) Pressure joint shall be made on the thread o

45、nly. A suitable jointing material may be applied to the threads. (6) Direct mounting flat bottom hole (7) Direct mounting through hole (8) Compressiong fitting adaptor Figure 1b. Taper thread connections Figure 1. Correct methods of making pressure connectionsPage 6 EN 837-2 : 1997 BSI 1998 7.2 Spec

46、ial conditions 7.2.1 Mechanical shocks Pressure 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 Vibrations When the actual support of the pressure gauge is subject to vibration

47、s several solutions may be considered: use of liquid filled pressure gauges; when vibrations are large scale 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, often irregular, of the tip of the

48、 pointer. 7.2.3 Pressure pulses These are generally present when pressure gauges are installed 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 pointe

49、r oscillations. It is necessary to reduce these pulses of pressure by interposing a damper between the pressure source and the pressure responsive element. 7.2.4 Overpressure Any overpressure creates stress in the pressure responsive element and consequently reduces its life and accuracy. It is therefore always preferable to use an instrument whose maximum scale value is greater than the maximum working pressure and which will consequently absorb overpressure and surges more easily (see 4.2.1). Surge