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1、BRITISH STANDARD BS EN 874:1995 Gas welding equipment Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel Type of construction, general specifications, test methods The European Standard EN 874:1995 has the status of a British Standard ICS 25.160.30 Licensed Copy: sheffieldun shef
2、fieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 874:1995 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1995 BSI 10-1999 T
3、he following BSI references relate to the work on this standard: Committee reference WEE/18 Draft for comment 92/83315 DC ISBN 0 580 24678 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee WEE/18, Gas welding and cutting
4、appliances, upon which the following bodies were represented: British Compressed Gases Association British Railways Board Consumer Policy Committee of BSI Department of Trade and Industry (Consumer Safety Unit, CA Division) Health and Safety Executive LP Gas Association Railway Industry Association
5、South Bank University Welding Manufacturers Association (BEAMA Ltd.) Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 874:1995 BSI 10-1999i Contents Page Committees responsibleIns
6、ide front cover National forewordii Foreword2 Text of EN 874:19953 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 874:1995 ii BSI 10-1999 National foreword This British Standard has been prepared by
7、 Technical Committee WEE/18 and is the English language version of EN 874:1995 Gas welding equipment Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel Type of construction, general specifications, test methods, published by the European Committee for Standardization (CEN). EN 87
8、4:1995 was produced as a result of international discussion in which the UK took an active part. 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 doe
9、s not of itself confer immunity from legal obligations. Cross-references Publication referred toCorresponding British Standard EN 29090:1992BS EN 29090:1992 Specification for gas tightness of equipment for gas welding and allied processes EN 29539:1992BS EN 29539:1992 Specification for materials for
10、 equipment used in gas welding, cutting and allied processes ISO 3:1973BS 2045:1965 Preferred numbers Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 20, an inside back cover and a back cover. This standard has been updated
11、 (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 874
12、 April 1995 ICS 25.160.30 Descriptors: Welding equipment, oxygen cutting, oxyacetylene cutting, blowpipes, dimensions, safety, performance evaluation, testing conditions, tests English version Gas welding equipment Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel Type of constr
13、uction, general specifications, test methods Matriel de soudage aux gaz Chalumeaux oxy-gaz combustible (type machine doxycoupage) corps cylindrique Type de construction, spcifications gnrales, mthodes dessai Gasschweigerte Maschinenschneidbrenner mit zylindrischen Schaft fr Brenngas/Sauerstoff Bauar
14、ten, allgemeine Anforderungen, Prfverfahren This European Standard was approved by CEN on 1995-01-09. 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. U
15、p-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 un
16、der 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, Nether
17、lands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of reproduction and communication in any form and
18、by any means reserved in all countries to CEN and its members Ref. No. EN 874:1995 E Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 874:1995 BSI 10-1999 2 Foreword This European Standard has been prepared by the Technical Committee CEN/T
19、C 121, Welding, of which the secretariat is held by DS. 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 October 1995, and conflicting national standards shall be withdrawn at the latest by October
20、 1995. According to 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 King
21、dom. Contents Page Foreword2 1Scope3 2Normative references3 3Terminology3 4Definitions3 5Dimensions5 6Hose connections5 7Material5 8Marking6 9Safety and operational requirements6 10Test conditions7 11Instructions for use15 Annex A (informative) Cutting nozzles seats and fixing16 Annex B (informative
22、) Terminology, example of construction16 Figure 1 Fuel gas induction mixer (low and high pressure)4 Figure 2 Mixer without injector action4 Figure 3 Main specifications5 Figure 4 Fuel gas injector mixer6 Figure 5 Mixer without injector action6 Figure 6 Fuel gas injector mixer with backflow resistanc
23、e in accordance with 9.1.56 Figure 7 Overheating test8 Figure 8 Acceptance requirements9 Figure 9 Assembly for closing flat nozzle end faces10 Page Figure 10 Segment shape of copper plate, dimensions11 Figure 11 Assembly for closing nozzle end faces that are not flat13 Figure 12 Assembly for testing
24、 the resistance against backflow of heating oxygen in the fuel gas line14 Figure 13 Assembly for testing the resistance against backflow of fuel gas in the heating oxygen line15 Figure B.1 Blowpipe with built-in valves16 Figure B.2 Blowpipe with screw-on valve16 Figure B.3 Two-hose blowpipe17 Figure
25、 B.4 Heating and cutting nozzle with mixing point in the blowpipe17 Figure B.5 Gas mixing nozzle with mixing in the nozzle18 Figure B.6 Heating and cutting nozzle with mixing point in the blowpipe18 Table 1 Dimensions of the rack5 Table 2 Designation and symbols of the gases6 Table 3 Test conditions
26、8 Table B.1 List of terms19 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 874:1995 BSI 10-19993 1 Scope This standard is applicable to machine cutting blowpipes with cylindrical barrels where the nozzle centre is coaxial with the barrel
27、, operating with oxygen and fuel gas, with a cutting range from 3 mm to 300 mm cutting thickness, and which are fitted to a gas cutting machine. This standard specifies the characteristics of machine cutting blowpipes and gives specifications and corresponding tests. 2 Normative references This Euro
28、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 of these publications
29、 apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 560, Gas welding equipment Hose connections for equipment for welding, cutting and allied processes. EN 730, Gas welding equipm
30、ent Equipment used in gas welding, cutting and allied processes Safety devices for fuel gases and oxygen or compressed air General specifications, requirements and tests. EN 29090 (ISO 9090:1989), Gas tightness of equipment for gas welding and allied processes. EN 29539 (ISO 9593:1988), Material req
31、uirements for equipment used in gas welding, cutting and allied processes. ISO 3:1973, Preferred numbers Series of preferred numbers. 3 Terminology Terminology concerning machine cutting blowpipes is given in Annex B. The design details of the blowpipes are left to the discretion of the manufacturer
32、; the illustrations in the standard are solely to clarify the terms. 4 Definitions For the purposes of this standard, the following definitions apply. 4.1 Common types of mixing systems 4.1.1 injector-mixer mixing system in which the fuel gas and the oxidizing gas are mixed by the action of the latt
33、er which, being discharged from the orifice of the injector, reduces the pressure, thus entraining the fuel gas. Accordingly, when the valve in the fuel gas channel is closed while the oxidizing gas is normally discharged, the pressure in this channel is below the atmospheric pressure. If during the
34、 same time the fuel gas hose connecting nipple is exposed to the atmosphere, air will be entrained (fuel gas valve open) (see Figure 1) 4.1.2 mixer without injector action mixing system in which the fuel gas and the oxidizing gas are mixed when the latter is discharged from the orifice and meets the
35、 fuel gas which is discharged at nearly identical pressure. When the valve in the fuel gas channel is closed while the oxidizing gas is discharged, the pressure in this channel is higher than the atmospheric pressure. If during the same time the fuel gas hose connecting nipple is exposed to the atmo
36、sphere, oxidizing gas will be discharged (fuel gas valve open) (see Figure 2) 4.2 High pressure and low pressure blowpipes 4.2.1 high pressure blowpipe a blowpipe in which the pressure of both the fuel gas and the oxidizing gas measured immediately before the point of mixing is higher than the press
37、ure of the gas mixture measured downstream between mixer and nozzle (see Figure 2) 4.2.2 low pressure blowpipe a blowpipe in which the fuel gas pressure measured immediately before the point of mixing is lower than the pressure of the gas mixture measured down-stream between mixer and nozzle (see Fi
38、gure 1) 4.3 Blowpipes classified according to the possibility of varying the flow rate 4.3.1 Blowpipes with multiple flow rates A blowpipe giving a range of flow rates corresponding to a series of nozzles. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled C
39、opy, (c) BSI EN 874:1995 4 BSI 10-1999 4.3.1.1 blowpipes with multiple flow rates adjusted by means of the injector a blowpipe with multiple flow rates which are varied by means of a device for adjustment of the injector cross-section (blowpipe with variable injector) 4.3.1.2 blowpipe with multiple
40、flow rates adjusted by the pressure a blowpipe with multiple flow rates which are varied by adjusting the feed pressures (blowpipe with fixed mixer) 4.3.1.3 blowpipe with multiple flow rates adjusted by means of gas control valves a blowpipe with multiple flow rates which are varied by adjustment of
41、 the adjustment valves Figure 1 Fuel gas induction mixer (low and high pressure) NOTEPosition of the mixing systems. The mixing systems in accordance with 4.1.1 and 4.1.2 are usually in the blowpipe or in the nozzle. pf pm po pm Figure 2 Mixer without injector action Licensed Copy: sheffieldun sheff
42、ieldun, na, Tue Nov 07 05:34:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 874:1995 BSI 10-19995 4.4 Blowpipes classified according to the mixing position 4.4.1 blowpipes with preliminary mixer the mixture of heating oxygen and fuel gas is ensured by the injector-mixer located before the cutting
43、nozzle 4.4.2 blowpipes with nozzle mixing the heating oxygen and fuel gas ways are independent in the blowpipe and the head. The gases are mixed in the cutting nozzle (nozzle mixing) 4.5 Backfire, sustained backfire, flashback, backflow 4.5.1 backfire the return of the flame into the blowpipe with a
44、 popping sound, the flame being either extinguished or reignited at the nozzle 4.5.2 sustained backfire the return of the flame into the blowpipe with continued burning within the neck or mixer (This may be accompanied by an initial popping sound followed by a continuous hissing sound from the conti
45、nued burning within the blowpipe.) 4.5.3 flashback the return of the flame through the blowpipe into the hoses and even the regulators. It may also reach the acetylene cylinder, causing heating and decomposition of the contents 4.5.4 backflow flowing back of the gas with the higher pressure into the
46、 hose of the gas with the lower pressure. This can be caused by the nozzle exit becoming blocked or restricted 5 Dimensions 5.1 Shank diameter The diameter of the blowpipe cylinder shank (D) is preferably equal to one of the following values: 32 mm = usual diameter; 28 mm = useful diameter for porta
47、ble machines and robot equipment; 45 mm = used e.g. for automatic internal ignition systems; Tolerance of shank diametermm. 5.2 Shank length The shank length (L) is the length on which the blowpipe holder can be fixed. The shank length will be preferably equal to 50 mm, 100 mm, 160 mm, 250 mm, and 4
48、00 mm. If other lengths are to be used, they should comply with the series R 20 (ISO 3). 5.3 Rack The rack is not mandatory, unless required by the blowpipe fixing and height adjusting device. If a rack is fitted it shall comply either with type F or S, given in Table 1. Table 1 Dimensions of the ra
49、ck A spur tooth rack is characterized by its width, the module and pitch of its teeth, its position on the cylinder shank (dimension E in Figure 3). 6 Hose connections The nipples shall be either permanently fitted to the shank or detachable. The external profile of the nipples is left to the choice of manufacturer. Where a threaded union connection is used it shall conform to EN 560. 7 Material The material requirements, according to EN 29539, shall be fulfilled. 0 0,2 Spur t