Asme b40 1 1991 (american society of mechanical engineers)

~~ I N D D 840-1 ~~ 2595532 0077967 l T ASME-B40.1 ADOPTION NOTICE ASME-B40.1, "Gauges-Pressure Indicating Dial Type-Elastic Element," was adopted on October 3, 1994 for use by the Department of Defense (DoD) Proposed changes by DoD activities must be submitted to the DoD Adopting Activity: Commanding Officer, Naval Construction Battalion Center, Code 156, 1000 23rd Avenue, Port Hueneme,CA 93043-4301 DoD activities may obtain copies of this standard from the 700 Robbins Avenue, Standardization Document Order Desk, Building 4D, Philadelphia, PA 19111-5094 The private sector and other Government agencies may purchase copies from the American Society of Mechanical Engineers, 345 East 47th Street, New York, NY 10017 Custodians: Army - ME Navy - YD-1 Air Force - 11 Adopting Activity Navy - YD-1 FSC 6 DISTRIBUTION STATEMENT A Approved for public release; distribution is unlimited SPECIAL NOTICE ASME B40.1-1991 GAUGES - PRESSURE INDICATING DIAL TYPE - ELASTIC ELEMENT ASME 840.1-1991 was issued with misprints A complimentary copy of the corrected version is enclosed Please discard the original issue We apologize for any inconvenience MAY 1992 THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 East 47th Street, New York, N.Y 10017 K1591N ASME B40.1-1991 (REVISION OF ANSVASME B40.1-1985) - Gauges ! Pressure Dial Type Elastic Element ( I-"' Indicating i AN AMERICAN NATIONAL STANDARD :(1 I I ! ! \"., The American Society of Mechanical Engineers - IERICAN NATIONAL STANDARD Gauges - Pressure Indicating Dial Type Elastic Element - ASME B40.1-1991 (REVISION OF ANSVASME B40.1-1985) @ t The American Society of Mechanical Engineers 345 East 47th Street, New York, N.Y 10017 Date of Issuance: September 27, I991 This Standard will be revised when the Society approves the issuance of a new edition There will be no addenda or written interpretations of the requirements of this Standard issued to this Edition ASME is the registered trademark of The American Society of Mechanical Engineers This code or standard was developed under procedures accreditedas meeting the criteriafor American National Standards, The Consensus Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate The proposed code or standard was made availablefor public review and commentwhich provides an opportunity for additional publicinput from industry, academia, regulatory agencies, and the public-at-large ASME does not "approve," "rate," or "endorse" any item, construction, proprietary device, or activity ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentionedin this document, and doesnot undertake to insure anyone uti1izing.a standard againstliability for infringement of any applicable LettersPatent, nor assume a code or standardare expressly advised that the determination of the any such liability Users of validity of any such patent rights, and the risk of the infringement of such rights, is entirely their own responsibility Participation by federal agency representative(s)or person(s) affiliated with industry is not to be interpreted as government or industry endorsement ofthis code or standard ASME acceptsresponsibilityfor only those interpretations issued in accordance with governing ASME procedures andpolicies which preclude the issuanceof interpretations by individual volunteers No part of this document may be reproducedin any form, in an electronic retrieval systemor otherwise, without the prior written permission of the publisher Copyright O 1991 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A FOREWORD (This Foreword is not part of ASME 640.1-1991) ASME Standards Committee B40 is comprised of a balanced cross sectionof pressure gauge users, manufacturers, and interested members representing governmental agencies, testing laboratories, and other standards producing bodies All are convinced that national standards such as this one serve not only to provide product performance and configuration guidelines,but also to inform and update the specifier and user regarding the science of pressure gauge production, application, and The use standards are vehicles by which the Committee as a body’can transmitto users the benefits of their combined knowledge and experience as regardsthe proper and safe use of pressure gauges The Committee, in its continual effort to make the B40.1 pressure gauge standard more informative and comprehensive, has scrutinized this document and has made the following additions and improvements: (U) all definitions, previously listed in both the main document and the Appendix, have been combined; (b) certain new definitions havebeen added; (c) pressure equivalents of sea water, and water at 60°F have been added; (d) paragraphs related to Insatllation, Vibration Failure, and Vibration-Induced Failure have been added; (e) Accuracy Test Procedure has been clarified; cf) Liquid Filled Gauge Test added; (g) Case - Slow Leak Test added; (h) listing of referenced documents was removed because of an ASME ruling that would automatically accept all referenced documents as U S Standards This was not our intent when these references were included, and is beyond the scope of this Committee The formulation and approval of this Standard did not include the investigation or consideration of patents Neither ASME northe B40 Committee shallbe responsible for identifying applicablepatents or for conducting inquiriesinto the legal validity or scope of those patents brought to their attention Prospective users of this Standard are responsible for protecting themselves against anypatent infringement liability This Standard is advisory only Its use is entirely a voluntary matter and shall in no way preclude the manufacture or use of products that not conform Neither ASME nor the B40 Committee assumes responsibility for the effects of observance or nonobservance of recommendations made herein This Standard was approved by the B40 Standards Committee and approved as an American National Standard by the American National Standards Institute of January 14, 1991 iii ASME STANDARDS COMMITTEE B40 Specifications for Pressure and Vacuum Gauges (the following is the roster of the Committee at the time of approval of this Standard.) OFFICERS R D Bissell, Chairman A.B Schupp, Vice Chairman J Pang, Secretary COMMITTEE PERSONNEL R A Andrews, Span Instruments W H Baier, Dupage Institute G Becker, Consultant R D Bissell, Dresser Industries/lnstrument Division J C Bowen, Consultant R Bross, AMETEK, Inc./U.S Gauge Div M D Dantona, Duro Instrument Corp T A S Duff, Consultant P Moes, Defense General Supply Center D.B Pearl, Continental Precision Instruments Inc C J Reed, AMETEK, Inc G W Reichard, The Dickson Company S Rosenblaft, Weksler Instrument Corp C H Savage, 111, Naval Ship Systems H Schindler, Consultant J E Schott, Operating Maintenance Specialties A B Schupp, Trend Instruments, Inc W H Slonaker, Weiss Instruments, Inc R W Walkeman, Marshalltown Instruments B Williams, U.S Air Force F L Walicki, Alternate, Naval Ship Systems V CONTENTS Foreword Standards Committee Roster Pressure Gauges General 2.1 Pressure'Defined 2.2 PressureGauge Components 2.3 PressureGauge TerminoIogy Defined General Recommendations 3.1 Gauge Sizes Scope 3.2 3.3 3.4 3.5 Preferred Ranges Construction Accuracy InstalIation 111 V 1 1 13 13 13 13 16 17 Safety 4.1 Scope 4.2 General Discussion 4.3 Safety Recommendations 4.4 Reuse of Pressure Gauges 18 18 18 19 20 Cleanliness 5.1 General 5.2 Cleanliness Levels 5.3 Inspection for Cleanliness 5.4 Packaging 21 21 21 21 21 Pressure Gauge Testing 6.1 Calibration Standards 6.2 Verification TestProcedures 21 21 22 Ordering Parameters and Related Standards 7.1 Order Checklist 7.2 Conversion Factors (Customary Units to SI Units) 7.3 SI (DIN) Case Sizes 23 23 24 24 vii Figures Basic Pressure Terms .! Pressure Gauge Components (C Type Bourdon Illustrated) ElasticElements Cases CasesMounting Recommended Case and Mounting Dimensions i., Tables Accuracy Grades ., CleanIinessLevels SI(D1N)CaseSizes 11 17 22 24 Appendices A ' Some Definitions and Suggested Test Procedures Used to Measure New GaugePerformance Al Scope Evaluation Procedures B Gauges Used on Regulators B1 Scope B2 Recommendations B3 Installation 25 25 25 29 29 29 31 Tables A l Vibration Test Amplitudes B1 Ranges 27 30 A2 viii ASME 840.1-1991 GAUGES - PRESSURE INDICATING DIAL TYPE - ELASTIC ELEMENT adjustment, span - a means of causing a change in the angle of pointer rotation for a given change in pressure This adjustment is not generally accessible to the gauge user ambient pressure - see pressure, ambient bar - a metric pressure unit equivalent to 14.50 psi bellows - a thin walled, convoluted elastic pressure sensing element (see Fig 3) bezel - see ring Bourdon tube - a tubular elastic pressure sensing element May have "C," helical, spiral or other form (see Fig 3) brazing - a metal joining process wherein coalescence is produced by use of nonferrous filIer metal having a melting point above 800°F(425"C), but lower than that of the base metals joined calibration - the process of graduating the pressure scale or adjusting the mechanism to cause the gauge to indicate within specified accuracy limits calibration~ven~catio~l - the checking of a gauge by comparison with a given standard to determine the indication error at specified points of the scale case ring - see ring, cam case - the housing or container that supports, protects and surrounds the internals case, liquid filled - a case that is filled with a liquid such as glycerine or silicone fluid to a least 75% of its total internal voIume Liquid filled cases may be either open front or solid front types The purpose of this construction is to protect the internals from damage caused by severe vibration of pulsation or to exclude ambient corrosives, or both case, openfiont with case pressure relief- a case with a pressure relief device or openings and no partition between the pressure element and the window (see Fig 4) An alternateconstruction is a plastic window especially designed to relieve internal case pressure case, open fiont without case pressure relief - a case having no partition between the pressure element and the window, and no pressure relief devices or openings (see Fig 4) case, pressure tight - a case capable of maintaining a pressure differential between the inside and the outside of the case SCOPE ThisStandard is confined to analog, dial-type gauges, which, utilizing elastic elements, mechanically sense pressure and indicate it by means of a pointer moving over a graduated scale It does not include gauges of special configuration designed for specific applications, edge reading, deadweight or mercury floated piston gages, or any other gauges not utilizing an elasticelement to sense media pressure PRESSURE GAUGES, GENERAL 2.1 Pressure Defined See Fig 2.2 Pressure Gauge Components See Fig 2.3 Pressure Gauge Terminology Defined absolute pressure - see pressure, absolute absolute pressure gauge - see gauge, absolute pressure accuracy - the conformity of a gauge indication to an accepted standard or true value Accuracy is the difference (error) between the true value and the gauge indication expressed as a percent of the gauge span It is the combined effects of method, observer, apparatus, andenvironment Accuracy error includes hysteresis and repeatability errors, but not friction error It is determined under specific conditions accuracy, reference - the accuracy of a gauge under reference conditions [normal position at 73.4"F (23°C) and 29.92 in Hg barometric pressure] adjustment, pointer - a means of causing a change in indication The change is approximately equal over the entire scale Some examples of this type of adjustment are adjustable pointers, rotatable dials, rotatable movements, andother similar items This adjustment, if provided, is generally accessible to the gauge user (see para 6.2.3.4) ASME BYO.1 91 0759670 050358b - GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT ASME 640.1-1991 SAFETY - where lower pressure gauges could be installed in higher pressure systems; (i) systems containing radioactive or toxic fluids (liquids or gases); (IC) systems installed in a hazardous environment 4.1 Scope This section of the Standard presents certain information to guide users, suppliers, and manufacturers toward minimizing the hazards that could result from misuse or misapplication of pressure gauges with elastic elements The user should become familiar with allsections of this Standard, as all aspects of safety cannot be covered in this section Consult the manufacturer Or supplier for advice whenever there is'uncertainty about the safe application of a pressure gauge 4.2.5 When gauges are to be used in contact with media having known or uncertain corrosive effects or known to be radioactive, random or unique destructive phenomena can occur In such cases the user should always furnish the supplier or manufacturer with information relative to the application and solicit his advice prior to installation of the gauge 4.2.6 Fire and explosions within a pressure system can cause pressure element failure with very violent effects, even to the point of completely disintegrating or melting the pressure gauge Violent effects are also produced when failure occurs due to: (a) hydrogen embrittlement; (6) contamination of a compressed gas; (c) formation of acetylenes; (d) weakening of soft solder joints by steam or other heat sources; (e) weakening of soft soldered or silver brazed joints caused by heat sources such as fires; cf) corrosion; (g) fatigue; (II) mechanical shock; (i) excessive vibration Failure in a compressed gassystemcan be expected to produce violent effects 4.2 General Discussion 4.2.1 Adequate safety results from intelligent planning and careful selection and installation of gauges into a pressure system The user should inform the supplier of all conditions pertinent to the application and environment so that the suppliercan recommend the most suitable gauge for the application 4.2.2 The history of safety with respect to the use of pressure gauges has been excellent Injury to personnel and damages to property have been minimal In most instances, the cause of failure has been misuse or misapplication 4.2.3 The pressure sensing element in most gauges is subjected to high internal stresses, and applications exist where the possibility of catastrophic failure is present Pressure regulators, chemical (diaphragm) seals, pulsation dampers or snubbers, syphons, and other similar items, are available for use in these potentially hazardous systems The hazard potential increases at higher operating pressure 4.2.7 Modes of Pressure Gauge Failure 4.2.7.1 Fatigue Failure Fatigue failure caused by pressure induced stress generally occurs from the inside to the outside along a highly stressed edge radius, appearing as a small crack that propagates along the edge radius Such failures are usually more critical with compressed gas media than with liquid media Fatigue cracks usually releasethe media fluid slowly so case pressure buildup can be averted by providing pressure relief openings in the gauge case However, in high pressure elastic elements where the yield strength approachesthe ultimate strength of the element material, fatigue failure may resemble explosive failure A restrictor placed in the gauge pressure inlet will reduce pressuresurges and restrict fluid flow into the partially open Bourdon tube 4.2.4 The following systemsare considered potentially hazardous and must be carefully evaluated: (a) compressed gas systems; (6) oxygensystems; (c) systems containing hydrogen or free hydrogen atoms; (d) corrosive fluid systems (gas and liquid); (e) pressure systems containing any explosive or flammable mixture or medium; cf) steam systems; (g) nonsteady pressure systems; (h) systems where high overpressure could be accidentally applied; (i) systems wherein interchangeability of gauges could result in hazardous internal contamination or 4.2.7.2 Overpressure Failure Overpressure failure is caused by the application of internal pressure greater than the rated limits of the elastic ele18 ~~~ - ~~~ ~ ~~ GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT - ASME B40.1-1991 ment and can occur when a low pressure gauge is installed in a high pressure port or system The effects of overpressure failure, usually more critical in compressed gas systems than in liquid filled systems, are unpredictable and may cause parts to bepropelled in any direction Cases with pressure relief openings will not always retain expelled parts Placing a restrictor in the pressure gauge inlet will not reduce the immediate effect of failure, but will help control flow of escaping fluid following rupture and reduce the potential of secondary effects.' It is generally accepted that solid front cases with pressure relief backwill reduce the possibility of parts being projected forward in the event of failure The.window alone will not provide adequate protection against internal case pressure buildup, and can be the most hazardous component Short duration pressureimpulses (pressure spikes) may occur in hydraulic or pneumatic systems, especially when valves open or close The magnitude of the spikes may be many times the normal operating pressure, and may not be indicated by the gauge The result could be immediate failure, or a large upscale error A restrictor (snubber) may reduce the magnitude of the pressure transmitted to the elastic element ultimately failure of the pointer to indicate any pressure change 4.2.7.6 Vibration-Induced Fatigue Failure In addition to its effect on the gauge movement and linkage (see para 4.2.7.5) vibration may, in some instances, result in high loading of various parts of the pressure element assembly This loading could cause cracks in the element itself, or in joints Case pressure buildup may be slow, but it is possible that a large hole may suddenly develop, with a high rate of case pressure rise, which could result in a failure similar to an explosive failure 4.2.8 Pressure Connection See recommenda- tions in para 3.3.4 4.3 Safety Recommendations 4.3.1 Operating Pressure The pressure gauge selected should have a full scale pressure such that the operating pressureoccurs in the middle half (25% to 75%) of the scale The full scale pressure of the gauge selected should be approximately two times the intended operating pressure Should it be necessary for the operating pressure to exceed 75% of full scale, contact the supplier for recommendations This does not apply to test, retarded,or suppressed scale gauges 4.2.7.3 Corrosion Failure.Corrosion failure occurs when the elastic element has been weakened through attack by corrosive chemicals present in either the media inside or the environment outside it Failure may occur as pinhole leakage through the element walls or early fatigue failure due to stress cracking brought about by chemical deterioration or embrittlement of the material A chemical (diaphragm) seal should be considered for use with pressure media that may have a corrosive effect on the elastic element 4.3.2 Use of Gauges Near Zero Pressure The use of gauges near zero pressureis not recommended because the accuracy tolerance may be a large percentage of the applied pressure If, for example, a O/ 100 psi Grade B gauge is used to measure psi, the accuracy of measurement will be + psi, or +50% of the applied pressure In addition, the scale of a gauge is often laid out with takeup, which can result in further inaccuracies when measuring pressures that are a small percentage of the gauge span For the same reasons, gauges should not be used for the purpose of indicating that the pressure in a tank, autoclave, or other similar unit has been completely exhausted to atmospheric pressure Depending on the accuracy and the span of the gauge and the possibility that takeup is incorporated at the beginning of the scale, hazardous pressure may remain in the tank even though the gauge is indicating zero pressure A venting device must be used to completely reduie the pressure before unlocking covers, removing fittings, or performing other similar activities 4.2.7.4 Explosive Failure Explosive failure is caused by the release of explosive energy generated by a chemical reaction such as can result when adiabatic compression of oxygen oc'curs in the presence of hydrocarbons It is generally accepted that there is no known means of predicting the magnitude or effects of this type of failure For this mode of failure, a solid wall or portion between the elastic element and the windowwill not necessarily prevent parts being projected forward 4.2.7.5 Vibration Failure The mostcommon mode of vibration failure is that wherethe movement parts wear because of high cyclic loading caused by vibration, resulting in gradual loss of accuracy, and, 19 ASME Bq0.L 9L œ 0757670 0503588 œ - GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT ASME 640.1-1991 4.3.3 Compatibility With thePressure Medium - of t h modes of failure outlined in para 4.2.7 The hydraulic effect duetopressureelementfailure could cause the window to beprojected forward even when a case having a solid front is employed The elastic element is generally a thin walled member, which of necessity operates under high stress conditions and must, therefore, be carefully selected for compatibility with the pressure medium being measured None of the common element materials is impervious to every type of chemical attack The potential for corrosive attack is established by many factors, including the concentration, temperature, and contamination of the medium The.user should inform the gauge supplier of the installation conditions so that the appropriate element materials can be selected 4.3.7 Restrictor Placing a restrictor between the pressure connection and the elastic element will not reduce the immediate effect of failure, but will help control flow of escaping fluid following rupture and reduce the potential of secondary effects 4.3.8 Specific Service Conditions 4.3.8.1 Specific applications for pressure gauges exist where hazards are known In many instances, requirements for design, construction, and use of gauges for these applications are specified by state orfederal agencies or Underwriters Laboratories, Ine Some of these specific service gauges are listed below The list is not intended to include all types, and the user should always advise the supplier of all application details 4.3.4 In addition to the factors discussed above, the capability of a pressure element is influenced by the design, materials, and fabrication of the joints between its parts Common methods of joining are soft soldering, silver brazing, and welding Joints can be affected by temperature, stress, and corrosive media Where application questions arise, these factors should be considered and discussed by the user and manufacturer 4.3.8.2 Acetylene Gauge A gauge designed to indicate acetylene pressure It shall be constructed using materials that are compatible with commercially available acetylene The gauge may bear the inscription ACETYLENE on the dial 4.3.5 Some special applications require that the pressure element assemblyhave a high degree of leakage integrity Special arrangement should be made between manufacturer and user to assure that the allowable leakage rate is not exceeded 4.3.8.3 Ammonia Gauge A gauge designed to indicate ammonia pressure and towithstand the corrosive effects of ammonia The gauge may bear the inscription AMMONIA on the dial It may also include the equivalent saturationtemperature scale markings on the dial 4.3.6 Cases 4.3.6.1 Cases, Solid Front It is generally ac- cepted that a solid front case per para 3.3.1 will reduce the possibility of parts being projected forward in the event of elastic element assembly failure An exception is explosive failure of the elastic element assembly 4.3.8.4 Chemical Gauge A gauge designed to indicate the pressure of corrosive or high viscosity fluids, or both The primary material(s) in contact with the pressure medium may be identified on the dial It may be equipped with a chemical (diaphragm) seal, pulsation damper, or pressure relief device, or a combination These devices help to minimize potential damage to personnel and property in the event of gauge failure They may, however, also reduce accuracy or sensitivity, or both 4.3.6.2 Cases, Liquid Filled It has been general practice to use glycerine or silicone filling liquids However, these fluids may not be suitable for all applications The should be avoided where strong oxidizing agents including, but not limited to, oxygen, chlorine, nitric acid, and hydrogen peroxide are involved In the presenceof oxidizing agents, potential hazard can result from chemical reaction, ignition, or explosion Completely fluorinated or chlorinated fluids, or both, may be more suitable for such applications The user shall furnish detailed information relative to the application of gauges having liquid filled cases and solicit the advice of the gauge supplier prior to installation Consideration should also be given to the instantaneous hydraulic effect that may be created by one 4.3.8.5 Oxygen Gauge A gauge designed to indicate oxygen pressure Cleanliness shall comply with Level IV (see section 5) The dial shall be clearly marked with a universal symboland/or USENO OIL in red color (see para 6.1.2.1) 4.4 Reuse of Pressure Gauges It is not recommended thatpressure gauges be moved from one application to another Should it be 20 ~ - ~ ~~~ ~ ~ ~ ~~~~~ ~~~ ~~ ~ GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT - ASME 840.1-1991 necessary,however, the following must be considered the solvent used to flush the pressure element assembly is evaluated When black light radiation methods are employed, the manufacturer should ascertain that the solvent usedwilldissolve all hydrocarbons that could be present and that all hydrocarbons are detectably fluorescent under black light It may be necessary for the gauge manufacturer to add fluorescent additives to certain suspected contaminants to make their detection possible The dimensions of particles and fibers are usually determined by microscopic examination of filter paper through which the flushing solvent has been passed 4.4.1 ChemicalCompatibility The consequences of incompatibility can range from contamination to explosive failure For example, moving an oil service gauge to oxygen services can result in explosive failure 4.4.2 Partial Fatigue The first installation may involve pressure pulsation that has expended most of the gauge life, resulting in early fatigue in the second installation 4.4.3 Corrosion Corrosion of the pressure element assembly in the first installation may be sufficient tocause early failure in thesecond installation 5.4Packaging 4.4.4 Other Considerations When reusing a gauge, allguidelines covered in this Standard relative to application of gauges should be followed in the same manner as when a new gauge is selected Gauges shall be packaged in such a manner that specified cleanliness requirements are maintained The user shall takeproper precautions so that cleanliness levels for socket and pressureelement are maintained after the gauge is removed from its package for installation CLEANLINESS 5.1 General This section provides standardized reference for gauge users in specifying cleanliness requirements and guidance to manufacturers in meeting these requirements If gauge cleanliness is important for the application, such as for use on equipment involving food processing, life support, or oxidizing fluids, the user should specify the appropriate level of cleanliness listed in Table If the cleanliness requirements of the intended application arenot covered in this Table, the user should so advise the manufacturer PRESSURE GAUGE TESTING 6.1 Calibration Standards 6.1.1 General Discussion 6.1.I.I CompIete information regarding ma- nometers and piston gages is contained in ASMEI ANSI PTC 19.2 In computing the accuracy of these instruments, their geographid location must be accurately ascertained and corrections applied as outlined in NIST Manometry Manual and NIST Piston Gage Manual 6.1.1.2 Working standards (gauges or transducers) used as calibration standards shall have an accuracy that is significantly better than that of the gauges to be tested and that has a documented path to NIST (see para 6.1.2.1) Refer toNIST Technical Note on Error Assessment) 5.2CleanlinessLevels Cleanliness is determined by the size and quantity of maximum permmissible solid contaminants on wetted surfaces or by the quantity of contaminant (hydrocarbons) discernible in the fluids used to flush or clean such surfaces, or by both Common cleanliness levels are defined in Table 6.1.I.3 Working standards shall be tested before and after a period of use The frequency of recalibration will depend on their ability to retain their accuracy during use The indicating error for each cardinal point and the date of last calibration shall be noted prominently on the frontof the instrument 5.3 Inspection for Cleanliness Hydrocarbon concentration may be determined by methods such as infraredspectrophotometry or black light (ultraviolet) radiation of the long wavetype [approximately3600 angstrom units (360nm)], where 6.1.1.4 Indicating dial gauges used as working standards may be equipped with a device or devices to minimize parallax reading errors The test gauge 21 - GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT ASME 840.1-1991 TABLE ~ - CLEANLINESSLEVELS ~~ Allowable Size andQuantity Fibers Particles Cleanliness Maximum Level Cleanliness Requirements General Size [Note (111 Applicable to All Levels I Normal cleanliness attained through high standardshop practices IV Gauge shall be free of visually [Note (411 (unaidedeye) detectable moisture and foreign matter (chips, slivers, weldslag or splatter,shopsoil,greases,oils, or other Contaminants)that could be mechanically detrimental to proper function of gauge (Micrometers) Maximum Quantity [Note (211 Size (Micrometers) Quantity [Note (211 Hydrocarbon PPm [Note (311, Maximum No limit No limit No limit No limit No limit Less than 100 No limit 25 O Less than 700 No limit 10 50 1001500 Over 500 70011 O00 Over 1000 O - NOTES: (1) Levels II and III intentionally omitted (2) Quantity = number by count per solvent flush (3)Ppm per solventflush (approximatelythe volume contained by the wetted surface) i4) Excluding particle, fiber, and hydrocarbon detectionprocedures should not have a stop pin unless it is located below the true zero pressure point of the graduated scale See para 6J.2.1 and Table for recommended accuracy and sizes 6.1.2.2 Accuracy Grades 4A and 3A Manom- eters or piston gages (as appropriate) 6.1 -2.3Accuracy Grades 2A, IA, A, B, C, and D 6.1.1.5 Liquid pressure media should not be (a) 30 in Hg vac through 100 psi or -100 kPa through 1000 kPa - manometer or piston gage, specially calibrated test gauge, or transducer (b) Above 100 psi or 1000 kPa - piston gage, test gauge specially calibrated, or transducer used to calibrate gauges where the weight of the liquid in the pressure element will induce errors, This effect is greater on low pressure range gauges 6.1.2 Recommended Standards 6.1.2.1 Use of the instruments suggested below is not mandatory, but the standards of weight, density, and linear measurements used in manufacturing and calibrating the test instrument shall conform to equivalent measuring standards that have been calibratedat the National Institute of Standardsand Technology and shall be documented The working standard,at the pressure being tested, shall be at least four times as accurate as the gauge being tested If the accuracy levelis less than four times, allowance for error in the standard is necessaly If a liquid pressure medium is used, correction for liquid head effect is necessary CAUTION: Piston gages containing oil or other hydrocarbon fluids shall not be used to calibrate oxygen gauges or gauges cleaned to Level IV See Table 6.2 Verification Test Procedures The following procedures are suggested when testing a pressure gauge todetermine its compliance with the accuracy grades defined in para.3.4 Statistical methods or alternate test procedures, or both, may be used when agreed to by the manufacturer and the user 6.2.1 Reference Temperature(All Grades) A temperature of 73.4"F (23°C) shall be the reference standard for testing allgauges Temperature compensated gauges shall be tested at several ambient temperatures within the range specified by the manufacturer 22 ASME B q O - 91 ~ ~ ~~~~ ~~ ~~ ~~ m 0759670 0503591 m ~~ ~ ~ - ~ \ "~ ~ GAUGES PRESSURE INDICATING DIAL TYPE ELASTIC ELEMENT - ASME B40.1-1991 proached from both increasing and decreasing pressure directions; in a single pressure cycle, expressed in percentage of span The hysteresis value is lower if the pressure excursion is less than full scale Hysteresis is part of the accuracy 6.2.2 Liquid Head When used in connection with an air piston gauge, there shall be no liquid in the gauge or in the lines between the gauge and the piston gauge 6.2.3 Procedures 6.2.3.1 Accuracy (a) Grades 3A and 4A On& Before conducting the 6.2.3.4 Pointer Adjustment Pointer adjustment can only be used to match the indication to a reference pressure at one point on the scale and should not be depended upon to recalibrate the gauge Such an adjustment could cause a significant error at pressures above or below the setting point accuracy test, subject the gauge to a pressure equal to the maximum scale pressure (or vacuum) Conduct the accuracy test within 10 (b) All Grades Known pressure shall be applied at each test point on increasing pressure (or vacuum) from one end to the other end of the scale At each test point the gauge shall be read,lightly tapped, and then read again The same sequence shall be repeated on decreasing pressure (or vacuum) The entire set of upscale and downscale readings shall then be repeated ORDERING PARAMETERS AND RELATED STANDARDS 7.1 OrderChecklist The following includes things to consider and questions to answer when ordering pressure gauges Accuracy Grade 4A 3A, 2A, lA, A B, C, D Recomrnendcd Minimum Number of test Points [Note] 7.1.1 If user does not require assistance with selection and recommendation for serviceinvolved, specify: (U) manufacturer's catalog number, size, range, and connection location and size; and (b) variations or accessories, or both, if required 10 N O T E The test points shall be distributed over the dial range and shall include points within 10% of the ends of the dial range 7.1.2 If user requires moderate assistance, specify: (U) range (specify units of measure) (see para 3.2); (b) accuracy (see para 3.4); (c) size (para 3.1 and Fig 6); (d) material and method of joining of pressure containing components; (e) connection type, location, and size; cf) mounting (stem, surface, or flush) (see Fig 6); (g) approved manufacturer's catalog number; and (h) variations or accessories, or both The error can be determined from the data obtained in the two pressure cycles and is equal to the maximum error at each test point, in either direction, after tapping, For Grade 4A gauges only, the error must remain with tolerance both before and after tapping When expressed as a percentage of span, the error shall not exceed the limits in Table 1for the applicable grade of accuracy 6.2.3.2 Repeatability Repeatability can be determined from the data obtained in the two pressure cycles It is the difference between any two readings taken after tapping, at the same pressure, approached from the same direction, and in the two pressure cycles, expressed in percentage of span More than two pressure cycles may be desirable Repeatability does not include hysteresis or friction error 7.1.3 If user requires detailed assistance, specify items listed inpara 7.1.2 plus the applicable portions of the following: ( U ) pressure fluid, name and state (gas or liquid), concentration, temperature, and material of equipment; (b) pressure pulsation range and frequency; (c) sudden pressure (less than 1/10 sec) increase or decrease; (d) case and ring materials; (e) window material; cf) environmental conditions such as: (-I) vibration frequency and amplitude (2) temperature 6.2.3.3Hysteresis Hysteresis can bedetermined from the data obtained in the two pressure cycles It is the difference at each test point between increasing pressure and decreasing pressure readings taken after tapping, at thesame test point, ap23 GAUGES - PRESSUREINDICATING DIALTYPE - ELASTICELEMENT ASME B40.1-1991 TABLE Circle SI (DIN)CASE SIZES OutsideMounting Case Bolt Diameter mm in Gauge Size Diameter mm: in ~~ 1.97 50 63 3.74 50 ao 1O0 160 60 75 95 116 I 78 2.36 2.95 63 4.57 7.01 1O0 160 (3) indoor and outdoor use (4) corrosive atmosphere (5) dust (6) weather resistance (7) humidity (8) mechanical shock (g) associated equipment ozJin.' (ounce per square inch) in.Hg (mercury) [Note 31 = SI Unit Paipascat) 2.540 O0 E - 02 3.048 O0 E - O 2.486 4E + m(meter) m Pa + 2.488 E +2 Pa 2.983 E E 6.451 60 + 03 Pa 9.290 30 E - 02 (square meters) mz 6.894 76 E 6.894 76 E + 03 4.309 22 3.386 38 -m2 04 - O2 + 02 E + 03 E Factor [Note (111 = SI Unit micron 1.000 O0 E - 06 m OF(degree (OF - 32)/1.8 "C(degree Fahrenheit) Celsius) NOTES: (1) Conversion factors are expressed as a number between 1.0 and 10.0 with five decimal places This number is followed by the letter E (for exponent), a plus or minus symbol, and two digits indicating the power of 10 by which the number must be multiplied to correctly place the decimal point The plus or minus indicates the direction the decimal must be moved: plus to the right, minus to the left EXAMPLES: (a) 2.540 O0 E - 0.2 means 2.540 O0 X lo-, and equals 0.025 400 (b) , 0.013 25 E + 05 means 1.013 25 X 105 and equals 101 325 (2) The bar is a unit outside the SI system that is nevertheless recognized by the Comitt6 International des Poids et Measures (CIPM) bar X 1.000 000 E + @=Pa (3) Mercury at 32°F (WC) The customary measuring units are listed below with their corresponding SI units and conversion factor will yield the correct value in SI units Conversion Factor [Note (111 1.013 25 E 05 2.48 3.15 3.94 6.30 ao Conversion Customary Unit X 7.2 Conversion Factors (Customary Units to SI Units) Customary X Unit atmosphere (standard) in.(inch) ft(fo0t) in H,O(water) (ZWC) in H,O(water) (60°F) ft H,O [Note (2)] insz(square inches) ft2 (square feet) psi (pound force per square inch 7.3 SI (DIN) Case Sizes This Standard defines gauge size as the approximate inside diameter of the case, in inches, at the dial Other standards, such as the German DIN series, define.gauge size as the precise outside diameter of the case Because of this difference, a B40 gauge and DIN gauge may not be interchangeable, even though the nominal sizes are approximately 63.5 mm inside the case at the face of the dial The outside diameter of the case may be as large as 70 mm, i.e., over 10% larger than a DIN 63 mm gauge The dimensions given in Table are taken from the DIN standards Pa bar [Note (2)) Pa Pa 24 APPENDIX A SOME DEFINITIONS AND SUGGESTED TEST PROCEDURES USED TO MEASURE NEW GAUGE PERFORMANCE (This Appendix is not an integral part of ASME 840.1-1991 and is included for information purposes only.) A I SCOPE A2.4 Pointer Adjustment Per this Standard (see para 6.2.3.4) This Appendix is intended to provide an outline of the parameters used when evaluating new gauge performance and to suggest evaluation outlines These test methods may or may not satisfy the requirements of the intended application When it is known that the gaugeswill encounter conditions more severe or less severe than those specified, the test may be modified to match more closely the application A functional test in the intended application is generally the best evaluation method A2.5 Friction Friction can be determined from data obtained in the accuracy test It is the difference between the readings taken before and after the gauge is lightly tapped A2.6 Error, Position The gauge shall be mounted in its normal calibrating position (see para 3.4.3.10) and checked for accuracy in accordance with para 6.2.3.1 The gauge WARNING: FAILURES DURING FRESSURE shall then be placed in its intended operating posiTESTING ARE UNPREDICTABLEAND MAY tion(s) and again checked for accuracy in accordance CAUSE PARTS TO BE PROPELLED IN ANY DIwith para 6.2.3.1 The difference between the two RECTION ALL PRESSURE TESTING SHOULD sets of readings is the position error BECONDUCTED BY QUALIFIED PERSONNEL USING APPROPRIATE SAFETY EQUIPMENT SUCH AS SAFETY GLASSES, SHIELDS, A2.7 High Temperature Error OR ENCLOSURES, OR A COMBINATION, TO The gauge shall be tested for accuracy in accordPREVENTPERSONALINJURY AND' PROPance with para 6.2.3.1 The gauge shall thenbe ERTY DAMAGE READ SECTION BEFORE placed in a temperature test chamber at the manuCONDUCTING ANY TESTING facturer's rated maximum operating temperature and allowed to stabilize for a period of not less than hr A2.1 Accuracy The gauge shall then be checked for accuracy at this temperature, in accordance with para 6.2.3.1 The Per this Standard (see para, 6.2.3) difference in readings at each test point between room temperature and the maximum operating temA2.2 Repeatability perature is the high temperature error Per this Standard (see para 6.2.3.3) A2 EVALUATlON.PROCEDURES A2.8 Low Temperature Error A2.3 Hysteresis The gauge shall be tested for accuracy in accordance with para 6.2.3.1 The gauge shall then be Per this Standard (see para 6.2.3.3) 25 / High or positive permissible 100 / / - permissible limit of error Desired charactethtic / (zero error curve) \ Hysteresis error Offset error t / / /- Input Pressure (Percentageof Span) / FIG A I HYSTERESIS AND OFFSET ERROR 26 O0 O759670 5 ~ ~ ~ TABLE A I VIBRATION TEST AMPLITUDES placed in a temperature test chamber at the manufacturer’s rated minimum operating temperatureand allowed to stabilize for a period of not less than hr The gauge shall then be checked for accuracy at this température, in accordance with para 6.2.3.1 The difference in readings at each test point between room temperature and the minimum operating temperature is the low temperature error Frequency Range, HZ Peak to Peak Vibration Amplitude, in 0.060+/-0.012 to 15 16 to 25 26 to 33 0.010+/-0,002 34 to 40 41 to 60 A2.9 Storage Temperature 0.040+/- 0.008 0.020+/- 0.004 0.005+/- 0.001 about 15 sec The frequencies and locations at which resonances occur shall be noted The gauge shall be tested for accuracy in accordance with para 6.2.3.1 The gauge shall then be placed in a temperature test chamber at the manufacturer’s high limit of storage temperature for aperiod of 24 hr The gauge shall then be placed in a temperature test chamber at the manufacturer’s low limit of storage temperature for a period of 24 hr This 48 hr cycle shall be repeated four times for a total of five complete cycles The gauge shall then be allowed to stabilize at room temperature and then be checked for accuracy, in accordance with para 6.2.3.1 The difference between the twoaccuracy tests is the effect of storage temperature expressed as a percentage of span A2.10.3 Endurance Test The gauge shall be tested for a period of hr in each of three mutually perpendicular axes (6 hr total) at the resonant frequency If more than one resonant frequency exists, the test shall be conducted at the highest resonant frequency If no resonance is observed, the test shall be in accordance with Table Al Test for accuracy in accordance with para, 6.2.3.1 The difference between the two accuracytests is the effect of vibration expressed as a percent of span A2.11 Pressure, Proof N O T E This test is applicable only to new gauges and is not intended for gauges that have been fatigue tested or otherwise had their useful life reduced A2.10 Vibration A2.10.1 Vibration Tests The gauge shall be tested for accuracy in accordance with para 6.2.3.1 before starting the vibration tests Each of the tests specified below shall be conducted separately in each of three mutually perpendicular axes All tests in one axis shall be completed before proceeding to tests in another axis The gauge under test shall be secured to the vibration table in the same manner that it will be secured in selvice In the case of surface or flush mounting, the panel shall be sufficiently rigid to ensure that its motion will be essentially the same as the motion of the platform of the vibration machine Input conditions should be monitored adjacent to the gauge mounting A pressure of 50% +5% of full scale shall be applied to the gauge under test during vibration This pressure may be applied by pressurizing the gauge and sealing the pressure port The gauge shall be tested for accuracy in accordance with para 6.2.3.1 Apply proof pressure to the gauge under test and maintain for Release pressure and allow gauge to stabilize Test for accuracy in accordance with para 6.2.3.1 The difference between the two accuracy tests is the effect of proof pressure expressed as a percentage of span N O T E Proof pressure may be a semidestructive test and should not be conductcd repcatcdly on the same gauge A2.12 Pressure, Rupture N O T E This test is applicable only to new gauges and is not intended for gaugcs that have had their uscful life reduced CAUTION: Select a reference gauge with a full scale pressure rating above the rupture pressure of the gauge under test toavoid damaging the reference gauge Apply pressure (hydraulic preferred) to the gauge under test, increasing at a rate not to exceed 20% of full scale per second of the gauge being tested The pressure atwhich the pressure elementassembly will no longer hold pressure is the rupture pressure A2.10.2 Exploratory Vibration Tests To determine the presence of resonances, the gauge under test shall be vibrated at frequencies from Hz to 60 Hz at a peak to peak amplitude not to exceed that shown in Table Al The change in frequency shall be made in discrete frequency intervals of approximately Hz and maintained at each frequency for 27 ASME B O O - L 9L 0759670 050359b b (6) Heat filled gauge tothe supplier's recommended maximum temperature and hold for a minimum of hr (c) Reduce temperature to the supplier's recommended minimum temperature and hold for a minimum of hr (d) Repeat the above cycle 20 times (e) No leakage of the fill fluid is permitted cf) The dial must remain readable No discoloration of the fill fluid which degrades readability of the dial is permitted A2.13 Fatigue The gauge shall be tested for accuracy in accordance with para 6.2.3.1 The gauge shall then be subjected to repeated applications of a pressure (hydraulic preferred)that produces an indication from 20% to 80% of the range of the gauge at a rate of 0.3 to 0.6 Hz (18 to 36 cpm) The application and release of the pressure shall be as smooth as practicable, so as not to subject the gauge mechanism to excessive upscale or downscale accelerations or high amplitude impulses (pressure spikes) The gauge shall be tested periodically for accuracy in accordance with the test specified in para 6,2.3.1 not less than hr after stopping the pressure cycling The difference between the first set of readings at each test point and the latest set of readings at each test point is fatigue error at this point NOTE If some slight discoloration is observed, additional exposure to the maximum temperature may be desirable, to determine whether further darkening of the fluid, to the point where readability is affcctcd, will occur A2.15 Case NOTE: Pressure limits different from 20% to 80% of thc range of the gauge can have a significant effecton the fatigue error and fatigue life NOTE: Applics only to sealed cases, without venting ( U ) Open Bourdon tube to allow gas to flow freely from the socket Open socket hole to 1/8 in diameter (6) For a liquid filled gauge - refill the case (c) With the gauge at 65'F/85"F, apply gas pressure to the socket, and slowly increase to allow case pressure to equal applied pressure at approximately psi/sec Record pressure required to activate relief mechanism (d) Case must relieve applied pressure without ejecting parts, other than the pressure relief device The gauge shall also be tested periodically for leakage of the pressure element assembly at full scale pressure The fatigue life is the number of cycles to leakage A2.14 Liquid Filled Gauges and Stability - Slow Leak Test - Seal Integrity NOTE: This test must be conducted on each fill fluid, NOTE Testing at higher or lower temperature may change results drastically.If gauge is to be used atother temperatures, test should berepeatedatthosetemperatures.Supplier'stemperaturelimit may not be excecded (a) Mount gauge normally in accordance with the supplier's instruction 28 APPENDIX B GAUGES USED O N REGULATORS (This Appendix is not an integral part of ASME 840.1-1991 and is included for information purposes only.) This Appendix is intended to emphasize and supplement the recommendations contained in this Standard and to guide personnel specifying and installing gauges used on regulators for oxy-fuelgas welding, cutting, and allied processes It should not be assumed that every test or safety procedure or method, precaution, equipment, or device is contained in this Appendix, or that abnormal or unusual circumstances máy not warrantsuggesting further requirements or additional procedures B2.2.3 Safety considerations are discussed in sec- tion B2.2.4 Cleanliness levels are detailed in section Gauges used on oxygen regulators shall have cleanliness equivalent to Level IV 82.2.5 Pressure gauge testing standards and procedures are discussed in section Additional information is outlined in Appendix A B2.2.6 Section contains helpful information rel- ative to ordering gauges, related standards, andconversion factors B1 SCOPE This Appendix is intendedto emphasize those parts of this Standard that are applicable to gauges commonly used on regulators for oxy-fuel gas welding, cutting, and allied processes and to provide specific considerations for gauge dial printing (marking) and gauge installation B2.3 Gauges Used on Regulators The following references to specific paragraphs of this Standard apply to gauges used on regulators Appropriate additional considerations are discussed B2.3.1 Sizes See para 3.1 The nominal gauge sizes are l K , 2, and 2?4 for regulator applications B2.3.2 Ranges See para 3.2 Common ranges for gauges used on regulators are listed in Table B1 by customary units andthe corresponding SI units (rounded to a maximum of two significant figures) It is recommended that nolarger graduations than those shown in Table B1 be printed (marked)on the gauge dial The spacing and displaying of the numerals marked on the gauge dial may vary for aesthetic reasons, provided that at least three numerals are displayed B2 RECOMMENDATIONS 82.1 General References Gauges used on regulators for oxy-fuel gas welding, cutting, and allied processes are to be governed by the recommendations of this Standard To facilitate the use of this Standard, references have been made to specific sections and paragraphs B2.3.3 Cases See paras 3.3.1 and 4.3.8 The cases commonly used for regulator gauge applications are open front with pressure relief Figure and paras 3.3.1.1 and 3.3.1.4 outline case construction B2.2 General Contents B2.2.1 Basic terms and definitions are outlined in section B2.2.2 General requirements are provided in section Gauges used on regulators are usually size 2, and 21/, mounted by the stem (socket), and have open frontcases with pressure relief They shall be grade B accuracy or better B2.3.4 Dials See para 3.3.2 lx, B2.3.4.1 Recommended units of measurefor gauges used on regulators are kPa and psi (psig) presented together (dual scale) 29 TABLE B I RANGES Customary Units, psi Range O115 0130 Smallest Numerals Graduation 0160 01100 0.5 1.o 1.o 2.0 2.0 O1150 Oll 60 01200 5.0 5.0 5.0 0150 Range SI Units, kPa Smallest Numerals Graduation 3.0 5.0 01100 01200 10 10 01350 20 01700 30 20 20 50 50 1O0 2.0 5.0 10 10 20 01400 20 50 50 1O0 1O0 10 10 50 50 011 O00 Oll 100 Oll 400 O12 O00 012 800 01500 10 01600 1O0 1O0 013 500 014 O00 200 300 017 O00 0110 O00 1O0 1O0 200 200 0/2,000 20 20 50 50 400 0114 O00 500 500 O00 O00 O00 O00 013,000 014,000 015,009 016,000 0/7,500 1O0 1O0 1O0 200 200 500 500 500 1O00 O00 O110,000 200 0120 O00 0128 O00 0135 O00 0140 O00 0150 O00 0170 O00 01300 01400 011,000 0/1,500 20 40 1000 1O00 1000 2000 B2.3.4.2 Paras 3.3.2.3, 3.3.2.4, and 3.3.2.5 are applicable Scale graduations on gauges installed on the output side of acetylene regulators are usually restricted to 15 psi, with the scale red-lined above 15 psi 200 200 200 500 400 O00 1O00 O00 1000 1000 2000 10 O00 10 O00 10 O00 B2.3.9 Safety See section Personnel specifying and installing pressure gauges used on oxy-fuel gas regulators should become familiar with the material presented in this section B2.3.10 Cleanliness See section Gauges used on oxygen regulators shall complywith cleanliness Level IV or better B2.3.4.3 Dials used on regulator gauges having ranges greater than 1000 psi usually contain a UL listing mark The UL listing mark indicates that the gauge design complies with Underwriters Laboratories Safety Standard UL 404 and gauges bearing the listing mark are subject to UL followup procedures B2.3.5 Pointer Length See para 3.3.3 B2.3.6 Pressure Connection Seepara 3.3.4 Gauges used on regulators are stem mounted and have ?&27 NPT or Y,-18 NPT taper pipe threads, per ANSVASME B1.20.1 B2.3.11 Pressure Gauge Testing See section The pressure medium used for testing shall maintain the required cleanliness level of the gauge under calibration or calibration verification The dead ended pressure element assembly of regulator gauges cannot be reliably cleaned once contaminated Gauges contaminated with hydrocarbon pressure media shall not be used on oxygen regulators B3 INSTALLATION B.2.3.7 Windows See para 3.3.7 Plastic windows are most commonly used on regulator gauges B3.1 References B.2.3.8 Accuracy See para 3.4 Gauges shall have an accuracy of Grade B or better (see Table 1) Applicable paragraphs in this section include: 3.4.1, 3.4.1.1, 3.4.1.2, 3.4.1.6, 3.4.1.9, 3.4.1.10, and 3.4.1.12 This section is limited to the installation of gauges on regulators, as used for oxy-fuel gas welding, cutting, and allied processes The installation and operation of regulators may be found in manufacturer’s 30 DO NOT install a low pressure gauge into the high pressure port on a regulator DO NOT use the gauge case for wrenching DO NOT interchange gauges from one gas application to another DO NOT exchange gauges from one regulator to another DO NOT conduct calibration verification using air from shop air lines, oil, or a contaminated pressure source DO NOT remove the restrictor installed in the gauge connection The restrictor limits gas flow and aids in limiting temperature rise due toadiabatic compression instruction manuals or handbooks, in the Occupational Safety and Health Standards for Industry (29 CFR,Part 1910), Subpart Q, and in the National Institute for Occupational Safety and Health (NIOSH), Safety and Healthin Arc Welding and Gas Welding and Cutting 83.2 General Precautions Oxygen and hydrocarbons (oil and greaseare common hydrocarbons) undercertain conditions can react violently, resulting in explosions, fire, and damage and injury to personnel and property Never allow oil or greaseto come intocontact withany external or internal part of the threaded fitting or internal portion of the pressure element assembly of oxygen gauges Even a minute amount of hydrocarbon can be hazardous in the presence of oxygen Regulator gauges should be installed or replaced only by skilled personnel whohave been properly instructed B3.4 Operation Precautions Gauges can fail during operation and the energy contained in compressed gases can produce violent effects should the pressure element assembly rupture DO always apply cylinder pressure slowly Heat due to adiabatic compression can cause ignition DO use safety glasses or provide eye protection DO stand with the cylinder between yourself and the regulator (cylinder valve outlet facing away) when opening the cylinder valve DO read CGA Safety Bulletin SB-8, Use ofOxyFuel Gas Welding and Cutting Apparatus DO NOT stand in front of or behind the pressure gauges when applying cylinder pressure to the regulator This will reduce the possibility of injury from flying parts should the pressure element assembly rupture DO NOT operate regulators without eye protection B3.3 Installation Precautions DO maintain thepressureelement assembly and connection cleanliness level required for the intended application DO refer to the manufacturer’s instruction manual for the correct pressure ranges to be used DO use the wrench flats provided on the gauge connection and the proper size wrench to secure the gauge to the regulator DO use only the thread sealantrecommended by the regulator manufacturer for the specific application 31 This document is printed on 50% recycled paper 50% RECOVERED PAPER MATERIAL means paper waste generated after the completion of the papermaking process, such as postconsumer materials, text books, envelopes, bindery waste, printing waste, cutting and converting waste, butt rolls, obsolete inventories, and rejected unused stock ISBN #O-7918-2118-8 t KO1591