00566693 PDF BRITISH STANDARD BS EN 472 1995 Pressure gauges — Vocabulary The European Standard EN 472 1994 has the status of a British Standard BS EN 472 1995 This British Standard, having been prepa[.]
BRITISH STANDARD Pressure gauges — Vocabulary The European Standard EN 472:1994 has the status of a British Standard BS EN 472:1995 BS EN 472:1995 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GEL/65, Measurement and control, upon which the following bodies were represented: British Coal Corporation British Gas plc British Nuclear Fuels plc Electrical Contractors’ Association Electricity Association Energy Industries Council GAMBICA (BEAMA Ltd.) Health and Safety Executive Institution of Gas Engineers The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Compressed Air Society British Compressed Gases Association British Fluid Power Association British Pressure Gauge Manufacturers’ Association Department of Trade and Industry (National Engineering Laboratory) This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 September 1995 © BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference GEL/65 Draft for comment 91/24810 DC ISBN 580 24628 Amendments issued since publication Amd No Date Comments BS EN 472:1995 Contents Committees responsible National foreword Foreword Text of EN 472 © BSI 01-2000 Page Inside front cover ii i BS EN 472:1995 National foreword This British Standard has been prepared by Technical Committee GEL/65 and is the English language version of EN 472:1994, Pressure gauges — Vocabulary published by the European Committee for Standardization (CEN) No British Standard is superseded A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application 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, pages i and ii, the EN title page, pages to and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 01-2000 EUROPEAN STANDARD EN 472 NORME EUROPÉENNE October 1994 EUROPÄISCHE NORM UDC 681.2.084.83:001.4 Descriptors: Measuring instruments, manometers, vocabulary English version Pressure gauges — Vocabulary Manomètres — Vocabulaire Druckmeßgeräte — Begriffe This European Standard was approved by CEN on 1994-10-19 CEN members are bound to comply 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 Secretariat 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 official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1994 Copyright reserved to CEN members Ref No EN 472:1994 E EN 472:1994 Foreword Contents This European Standard has been prepared by Technical Committee CEN/TC 141, Pressure gauges, of which the secretariat is held by AFNOR This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 1995, and conflicting national standards shall be withdrawn at the latest by April 1995 In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom Page Foreword Introduction Scope Definitions relating to pressure gauges 3 Definitions relating to pressure gauge components Definitions relating to the characteristics Index © BSI 01-2000 EN 472:1994 Introduction In the preparation of this International Standard, the following two principles have been followed as far as possible: — to standardize suitable terms without perpetuating unsuitable terms merely because they have been used in the past; — to discard any term which is used with different meanings and to replace it by a term which has an unequivocal meaning 2.7 differential pressure gauge a pressure gauge used to measure the difference between two applied pressure and/or vacuum values, the metallic pressure-responsive element(s) of which drive(s) one pointer 2.8 duplex pressure gauge Scope a pressure gauge used to measure two applied pressure and/or vacuum values, by means of two separate pressure-responsive elements in one case, each of which drives its own pointer This European Standard defines the fundamental and general terms to be used for pressure gauges 2.9 control pressure gauge Definitions relating to pressure gauges a pressure gauge fitted with one or more switches which open or close one or more control circuits depending on the pointer position 2.1 indicating pressure gauge 2.10 edgewise pressure gauge a measuring instrument which displays the value of the applied pressure by means of a pointer relative to a scale a pressure gauge with a rectangular dial for flush mounting in a panel or a control board, where the pivotal axis of the pointer lies in a plane parallel to the plane of the panel or control board 2.2 indicating pressure gauges with an elastic measuring element 2.11 liquid filled pressure gauge instrument in which the mechanical measuring sequence directly transmits the elastic deformation of the sensing element to the indicating device, consisting of a pointer and a graduated scale a pressure gauge, the case of which is filled with a liquid 2.3 pressure gauge a gauge incorporating safety features and particularly suitable for use with high pressure gases and steam an indicator of the applied (gauge) pressure with respect to the atmospheric pressure 2.4 vacuum gauge an indicator of the applied (gauge) vacuum with respect to the atmospheric pressure 2.5 combined pressure and vacuum gauge a combined indicator of the applied (gauge) pressure or vacuum with respect to the atmospheric pressure 2.6 absolute pressure gauge an indicator of absolute pressure, i.e pressure relative to a complete vacuum NOTE This description therefore does not apply to pressure gauges graduated in absolute pressure units, the indications of which are influenced by variations of atmospheric pressure © BSI 01-2000 2.12 safety pattern gauge Definitions relating to pressure gauge components 3.1 pressure-responsive element An elastic element which undergoes deformations under the effect of pressure variations It may be a Bourdon tube, diaphragm, diaphragm capsule, bellows or other type of element 3.1.1 bourdon tube a type of spiral pressure-responsive element where a tube with a non-circular cross-section is bent into a circular or coiled shape Under the effect of the internally applied pressure the tube tends to straighten The deflection induced is proportional to the pressure applied EN 472:1994 3.1.2 diaphragm 3.5.2 maximum pointer a type of pressure-responsive element usually in the form of a concentrically corrugated membrane where the pressure applied causes the diaphragm to deflect in proportion to the pressure a secondary pointer driven by the pointer which stays at the maximum value reached by the latter 3.1.3 capsule a screw, stud, or other projection, fitted to limit the travel of the pointer a type of pressure-responsive element comprising of two diaphragms suitably shaped and joint pressure-tight around their circumference The pressure commonly acts on the interior of the capsule and the expansion generated thus is proportional to the pressure 3.1.4 bellows a type of pressure-responsive element in the form of a thin-walled convoluted tube The change in its length is proportional to the pressure 3.2 movement an assembly by means of which the deformations of the pressure-responsive element are transformed and enlarged into an angular variation 3.3 pressure element assembly the assembly of all the pieces coming into contact with the fluid whose pressure is measured 3.4 connection The part by which the pressure gauge can be coupled to the pressure tapping of the plant, pipework or equipment 3.4.1 shank 3.5.3 pointer stop NOTE It is not the function of a pointer stop to act as an overload stop 3.6 adjustable mark a moving index operated from the outside and not driven by the indicating pointer, used to place a reference mark on the dial 3.7 case the casing which contains the pressure-responsive element, parts of the pressure element assembly and the movement It may also include a safety device The front face of the case may be circular, square or rectangular 3.8 blow-out device A safety device incorporated in the case or back plate to permit the rapid and safe dissipation of internal pressure in the event of a leakage or burst in the pressure responsive element 3.8.1 blow-out back a safety device incorporating the greater part of the back of the case 3.8.2 baffle wall the part of the gauge that includes the screwed connection, the spanner flats, square or hexagon, the spigot, and the inlet orifice a barrier between the pressure responsive element and the dial, so disposed that, in the event of a leakage or burst in the pressure responsive element, the blast would be dissipated away from the front 3.4.2 screwed connection 3.8.3 removable back plate the threaded portion of the shank a plate at the back of the case, that is removable for the purpose of giving access to the interior 3.5 pointer The index, the position of which, in relation to the scale, indicates the value of the measured pressure 3.5.1 adjustable pointer a pointer with an adjustable device for zero correction 3.9 flange the circular, square or rectangular part, removable or fixed, projecting from the case, on which the latter is mounted 3.10 window the transparent front intended for protection of the pointer, dial and control devices, if any © BSI 01-2000 EN 472:1994 3.11 bezel ring 3.16 adjustment the part which retains the window on the case operation of bringing a pressure gauge into a state of performance suitable for its use 3.12 clamp the part used for mounting clamp fixing pressure gauges on panel boards 3.13 spacer the distance piece, ring, or collar separating the window from the dial 3.14 dial that part of an indicating device, fixed or moving, which carries the scale or scales 3.17 user adjustment the operation intended to bring a pressure gauge into a state of performance and freedom from bias suitable for its use, employing only the means at the disposal of the user Definitions relating to the characteristics 4.1 nominal size 3.15 scale (of an indicating device) a conventional alpha-numerical designation relating to the size of the pressure gauge An ordered set of scale marks, together with any associated numbering, forming a part of an indicating device 4.2 nominal range 3.15.1 scale length for each scale range, the set of indicated values of the applied pressure for which a pressure gauge gives values within that scale range for a given scale, the length of the line between the first and the last scale marks and passing through the centres of all the shortest scale marks NOTE The nominal range is expressed in units of the applied pressure regardless of the units marked on the scale, and is normally stated in terms of its lower and upper limits, for example – 200 mbar to + 400 mbar NOTE The line may be real or imaginary, curved or straight 3.15.2 scale range for a given scale, the set of scale values between the extreme scale marks NOTE The scale range is expressed in the units marked on the scale, regardless of the units of the applied pressure and is normally stated in terms of its lower and upper limits, for example bar to 100 bar 3.15.3 scale division 4.3 span the modulus of the difference between the two limits of a nominal range of a pressure gauge EXAMPLE Nominal range – 200 mbar to + 400 mbar: span 600 mbar 4.4 specified measuring range the part of a scale between any two successive scale marks the set of values of an applied pressure for which the error of a pressure gauge is intended to lie within specified limits 3.15.4 scale spacing 4.5 accuracy class the distance between any two successive scale marks measured along the same line as the scale length a class of pressure gauge which meets certain metrological requirements that are intended to keep errors within specified limits NOTE Scale spacing is expressed in units of length, regardless of the units of the applied pressure or the units marked on the scale 3.15.5 scale numbering the set of numbers, associated with scale marks, which correspond to the set of values of the applied pressure defined by the scale marks © BSI 01-2000 NOTE An accuracy class is usually denoted by a number adopted by convention and called the class index 4.6 limits of permissible error the extreme values of an error permitted by specifications, regulations etc for a given pressure gauge EN 472:1994 4.7 error (of indication) of a pressure gauge 4.9 hysteresis the indication of a pressure gauge minus the true value of the applied pressure the property of a pressure gauge whereby its response to a given stimulus depends on the sequence of preceding stimuli 4.8 repeatability of a pressure gauge the ability of a pressure gauge to give, under defined conditions of use, closely similar responses for repeated applications of the same stimulus NOTE Although hysteresis is normally considered in relation to the applied pressure, it may also be considered in relation to influence quantities NOTE The defined conditions of use are usually as follows: — repetition over a short period of time; — use at the same location under constant ambient conditions; — reduction to a minimum of the variations due to the observer © BSI 01-2000 EN 472:1994 Index A E pointer stop 3.5.3 absolute pressure gauge 2.6 accuracy class 4.6 adjustable mark 3.6 adjustable pointer 3.5.1 adjustment 3.16 edgewise pressure gauge 2.10 error (of indication) of a pressure gauge 4.7 pressure element assembly 3.3 pressure gauge 2.3 pressure-responsive element 3.1 F R flange 3.9 removable back plate 3.8.2 repeatability of a pressure gauge 4.8 B baffle wall 3.8.2 bellows 3.1.4 bezel ring 3.11 blow-out back 3.2.1 blow-out device 3.8 Bourdon tube 3.1.1 C capsule 3.1.3 case 3.7 clamp 3.12 combined pressure and vacuum gauge 3.5 connection 3.4 control pressure gauge 2.9 D dial 3.14 diaphragm 3.1.2 differential pressure gauge 2.7 duplex pressure gauge H hysteresis 4.9 S M safety pattern gauge 2.12 scale (of an indicating device) 3.15 scale division 3.15.3 scale length 3.15.1 scale numbering 3.15.5 scale range 3.15.2 scale spacing 3.15.4 screwed connection 3.4.2 shank 3.4.1 spacer 3.13 specified measuring range 4.4 maximum pointer 3.5.2 movement 3.2 U I indicating pressure gauge 2.1 indicating pressure gauges with an elastic measuring element 2.2 L limits of permissible error 4.6 liquid filled pressure gauge 2.11 N user adjustment 3.17 nominal range 4.2 nominal size 4.1 nominal span 4.3 V P window 3.10 vacuum gauge 2.4 W pointer 3.5 © BSI 01-2000 BS EN 472:1995 BSI — British Standards Institution BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter 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 quality of our products and services We would be 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