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Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This code is a revision of GB/T 12242-1989 Performance test methods for safety valves. This code is modified based on ASME PTC 25:1994 Pressure relief devices - Performance test code (English version). The following main changes have been made with respect to ASME PTC 25: ——Editorial changes has been made to this code with respect to the original code in terms of structure and drafting rules in accordance with the requirements of GB/T 1.1; ——US standards for measurements and instruments cited in the original code are not cited in this code; ——The US units and calculation formulas adopted in the original code are converted into metric units and calculation formulas in this code. The following main changes have been made with respect to GB/T 12242-1989: ——The scope of application has expanded from safety valves to including non-reclosing pressure relief devices, and the code name has been changed accordingly; ——“Terms and definitions” is added; ——The content of test on rupture disk drag coefficient is added; ——The contents of in-service testing and bench testing are added; ——Annex A "Test report form", Annex B "Test summary report form" and Annex C "Examples of flow error determination" are added. Annexes A, B and C of this code are informative. This code replaces GB/T 12242-1989. This code was proposed by the China Machinery Industry Federation. This code is under the jurisdiction of SAC/TC 188 National Technical Committee on Valve of Standardization Administration of China. The previous edition of the code replaced by this code is as follows: ——GB/T 12242-1989. Performance test code - Pressure relief devices 1 Scope This code provides guidance and rules (including the preparation of test reports) for the operational characteristics (including mechanical properties) and relieving capacity testing of pressure relief devices. Those tests are used to determine the operational characteristics and relieving capacity of pressure relief device which is used to prevent overpressure in boilers, pressure vessels, and associated piping equipment. There are inlet and outlet conditions for the test procedures of this code, and steam, gas (air) or liquid (water) whose physical properties are known is used as the test medium. This code is applicable to the following types of reclosing and non-reclosing pressure relief devices: a) safety valve; b) rupture disk device; c) breaking/shear pin device; d) fusible plug device. Other pressure relief devices may be tested provided all parties to the test agree to accept the provisions of this code. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this code. However parties to agreements based on this code are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies. GB/T 12241 Safety valves - General requirements (GB/T 12241-2005, ISO 4126-1: 1991, MOD) GB/T 12243 Spring loaded safety valves (GB/T 12243-2005, JIS B 8210: 1994, MOD) 3 Terms For the purposes of this code, the terms and definitions given in GB/T 12241 apply. 3.1 General 3.1.1 pressure relief device device designed to prevent internal medium pressure from rising above a predetermined maximum pressure in a pressure vessel exposed to emergency or abnormal conditions 3.1.2 operational characteristics and flow capacity testing testing of a pressure relief device to determine its operating characteristics including measured relieving capacity 3.1.3 in-service testing testing of a pressure relief device while protecting the system on which it is installed to determine some or all of its operating characteristics using system pressure solely or in conjunction with an auxiliary lift device or other pressure source 3.1.4 bench testing testing of a pressure relief device on a pressurized system to determine set pressure and seat tightness 3.2 Types of pressure relief devices 3.2.1 reclosing pressure relief device pressure relief device that is closed after action a) safety valve automatic valve which discharges rated amount of fluid by virtue of the force of the medium itself but not any other external force to prevent the pressure from exceeding a rated safe value and, after the pressure returns to normal, closes to prevent the medium from continuing to flow out b) direct-loaded safety valve safety valve that overcomes the acting force generated by the pressure of the medium under the valve disk relying only on direct mechanical loading device such as counter weight, a lever plus counter weight or spring. c) assisted safety valve such safety valve can be opened with the help of a power assist device when the pressure is lower than the normal set pressure d) supplementary loaded safety valve such safety valve always maintains an additional force for enhancing the seal before its inlet pressure reaches the set pressure, with the additional force, i.e., the supplementary load, able to be provided by an external source of energy, reliably released when the safety valve inlet pressure reaches the set pressure and so designed that, assuming such load is not released, the safety valve can still reach the rated relieving capacity with its inlet pressure not exceeding the percentage of the set pressure specified by national regulations e) pilot-operated safety valve safety valve which is actuated or controlled by the medium discharged from a pilot valve which is a direct-loaded safety valve f) vacuum relief valve safety valve designed to admit fluid to prevent an excessive internal vacuum; it is designed to reclose and prevent further flow of fluid after normal conditions have been restored 3.2.2 non-reclosing pressure relief device pressure relief device designed to remain open after operation a) rupture disk device non-reclosing pressure relief device actuated by the static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a pressure containing disk b) breaking pin device non-reclosing pressure relief device actuated by inlet static pressure and designed to function by the breakage of a load-carrying section of a pin which supports a pressure containing member c) buckling pin device non-reclosing pressure relief device actuated by inlet static pressure and designed to function by the buckling of a load-carrying section of a pin which supports a pressure containing member d) shear pin device non-reclosing pressure relief device actuated by inlet static pressure and designed to function by the shearing of a load-carrying section of a pin which supports a pressure containing member e) fusible plug device non-reclosing pressure relief device designed to function by the yielding or melting of a plug of suitable melting temperature material 3.3 Safety valve dimensional characteristics 3.3.1 discharge area minimum sectional area of fluid flow path during valve discharge 3.3.2 flow area minimum cross-sectional area of flow between valve inlet end and closure member sealing surface 3.3.3 flow diameter diameter corresponding to the flow area 3.3.4 curtain area area of the cylindrical or conical discharge opening between the seating surfaces created by the lift of the disk above the seat, see Figure 1 3.3.5 lift actual travel of the disk away from closed position 3.3.6 rated lift design lift at which a valve attains its rated relieving capacity 3.3.7 seat angle angle between the axis of a valve and the seating surface. A flat-seated valve has a seat angle of 90° 3.3.8 seat area area determined by the seat mean diameter 3.3.9 seat mean diameter mean diameter of contact between the valve disk and the seat 3.4 Non-reclosing pressure relief device dimensional characteristics 3.4.1 net flow area area which determines the flow after a non-reclosing pressure relief device has operated. The (minimum) net flow area of a rupture disk is the calculated net area after a complete burst of the disk, with appropriate allowance for any structural members which may reduce the net flow area through the rupture disk device 3.5 Operational and flow capacity characteristics of pressure relief device 3.5.1 set pressure preset pressure under which the safety valve in operating conditions starts to open and the force opening the valve generated by medium pressure in specified operating conditions is balanced with that keeping the valve disk on the valve seat 3.5.2 overpressure pressure increase over the set pressure of a safety valve, usually expressed as a percentage of set pressure 3.5.3 re-seating pressure pressure at which the valve disk reestablishes contact with the seat or at which lift becomes zero 3.5.4 blowdown difference between set pressure and re-seating pressure expressed as a percentage of set pressure or in pressure units 3.5.5 relieving pressure set pressure plus overpressure 3.5.6 flow-rating pressure upper limit of relieving pressure specified by the standard or specification, which is the inlet static pressure at which the relieving capacity of a pressure relief device is measured 3.5.7 back pressure static pressure existing at the outlet of a pressure relief device due to pressure in the discharge system 3.5.8 built-up back pressure pressure existing at the outlet of a pressure relief device caused by the flow through that particular device into a discharge system 3.5.9 superimposed back pressure pressure existing at the outlet of a pressure relief device at the time the device is required to operate. It is the result of pressure in the discharge system from other sources 3.5.10 cold differential test pressure inlet static pressure at which a pressure relief valve is adjusted to open on the test stand. This test pressure includes corrections for service conditions of back pressure and/or temperature 3.5.11 tight test pressure inlet static pressure under which tightness test is conducted and under which the leak rate for flowing through the closure member seat 3.5.12 burst pressure value of inlet static pressure at which a rupture disk device functions 3.5.13 specified burst pressure of a rupture disk device value of increasing inlet static pressure, at a specified temperature, at which a rupture disk is designed to function 3.5.14 breaking pressure value of inlet static pressure at which a breaking pin, buckling pin or shear pin device functions 3.5.15 primary pressure pressure at the inlet in a pressure relief device 3.5.16 secondary pressure pressure existing in the passage between the actual discharge area and the valve outlet in a safety valve 3.5.17 simmer pressure audible or visible escape of fluid between the seat and disk at an inlet static pressure below the set pressure of safety valve and at no measurable capacity. It applies to safety valve on compressible-fluid service 3.5.18 theoretical relieving (discharge) capacity computed capacity expressed in gravimetric or volumetric units of a theoretically perfect nozzle having a minimum cross-sectional flow area equal to the flow area of a safety valve or net flow area of a non-reclosing pressure relief device 3.5.19 measured relieving (discharge) capacity relieving capacity of a pressure relief device measured at the flow-rating pressure, expressed in gravimetric or volumetric units 3.5.20 rated relieving capacity (certified discharge capacity) that portion of the measured relieving capacity permitted by the applicable code or regulation to be used as a basis for the application of a pressure relief device 3.5.21 equivalent calculated capacity calculated capacity of a pressure relief device when the service conditions for pressure, temperature or medium are different from the applicable conditions of rated relieving capacity 3.5.22 coefficient of discharge ratio of measured relieving (discharge)capacity to theoretical relieving (discharge) capacity 3.5.23 rated coefficient of discharge ratio of rated relieving capacity (certified discharge capacity) to theoretical relieving (discharge) capacity 3.5.24 chatter abnormal rapid reciprocating motion of the valve disk of a safety valve in which the disk contacts the seat 3.5.25 flutter abnormal, rapid reciprocating motion of the valve disk of a safety valve in which the disk does not contact the seat 3.5.26 reference conditions those conditions of a test medium which are specified by either an applicable standard or an agreement between the parties to the test, which may be used for uniform reporting of flow capacity testing results Flat-seated valve Curtain area = πDL Bevel-seated valve Curtain area = πB(D+DB)/2 Bevel-seated valve Curtain area = πB(D+DB)/2 Bevel-seated valve Curtain area = πB(D+DB)/2 Radial-seated valve Curtain area = πB(D+DB)/2 Radial-seated valve Curtain area = πB(D+DB)/2 L = lift D = smallest diameter at which seat touches disk DB = other diameter of frustrum of cone B = slant height of frustrum of cone θ = seat angle R = radius Note: Curtain area is the discharge area unless the disk attains sufficient lift for the flow area to become the smallest sectional area of the passage. Figure 1 Typical curtain areas of safety valves 4 General 4.1 The measurement deviation of this standard test is as follows: for the flow capacity testing, the deviation of the final flow capacity measurement shall not exceed ±2.0% of the measured value; for the operational characteristics testing, the deviation of the pressure measurement shall not exceed ±0.5% of the measured value; for the in-service testing and bench testing, the deviation of the pressure measurement shall not exceed ±1.0% of the measured value. 4.2 It is assumed that the testing facility has adequate capacity and sufficient pressure to conduct the tests specified in this code. The diameter of the test vessel for operational characteristics and flow capacity testing shall be at least ten times the device nominal inlet diameter when testing with steam or gas, and four times the pressure relief device nominal inlet diameter when testing with liquids. Operating conditions shall be maintained in accordance with the requirements of the procedure used (see 5.4). The duration of the test shall be that required to obtain the necessary performance and capacity data under stable conditions. 4.3 Field installation and/or abnormal operating conditions may adversely affect the function of the pressure relief device. It is not the intent of this code to attempt to assess the suitability or reliability of the pressure relief device under such conditions. Foreword i 1 Scope 2 Normative references 3 Terms 3.1 General 3.2 Types of pressure relief devices 3.3 Safety valve dimensional characteristics 3.4 Non-reclosing pressure relief device dimensional characteristics 3.5 Operational and flow capacity characteristics of pressure relief device 4 General 5 Operational characteristics and flow capacity testing of pressure release devices 5.1 Testing facility and instrument 5.2 Measurement methods 5.3 Test requirements 5.4 Test procedure 5.5 Computation of results 5.6 Test summary report 6 In-service and bench testing 6.1 Instruments and methods of measurements 6.2 In-service testing procedures 6.3 Bench testing procedures 6.4 Seat tightness test 6.5 Computation of results 6.6 Test summary report Annex A (Informative) Test report form A.1 Symbolic description of test record A.2 Test report form Table A.1 Test report form for pressure relief device tested with steam and water - Weighed-water method Table A.2 Test report form for pressure relief device tested with steam - Flow-meter method Table A.3 Test report form for pressure relief device tested with liquid - Flow-meter method Table A.4 Test report form for pressure relief device tested with air or other gases - Flow-meter method Table A.5 Test report form for pressure relief device tested with air or other gases - Sonic-flow method Table A.6 Test report form for pressure relief device tested with fuel gas - Flow-meter method Table A.7 Test report form for rupture disk device tested with air - Resistance coefficient method Annex B (Informative) Test summary report form Table B.1 Test summary report form of pressure relief valve - Steam medium Table B.2 Test summary report form of pressure relief valve - Water or liquid medium Table B.3 Test summary report form of pressure relief valve - Air, gas or fuel gas medium Table B.4 Test summary report form of rupture disk device - Air, gas or fuel gas medium Annex C (Informative) Examples of flow error determination 压力释放装置 性能试验规范 1范围 本标准为进行压力释放装置的动作性能试验(包括机械特性)及排量的试验提供指导和规则(包括编制试验报告)。压力释放装置用来防止锅炉、压力容器及相关管道设备的超压，而这些试验则用来确定压力释放装置的动作性能和排量。 本标准的试验程序有各种进口和出口条件状况，试验介质是使用其物理性质已知的蒸汽、气体(空气)或液体(水)。本标准适用于下列类型的重闭式和非重闭式压力释放装置： a)安全阀； b)爆破片装置； c) 折断/剪切销装置； d)易熔塞装置。 试验有关各方同意接受本标准的条款，本标准也可适用于其他压力释放装置。 2规范性引用文件 下列文件中的条款通过本标准的引用而成为本标准的条款。凡是注日期的引用文件，其随后所有的修改单(不包括勘误的内容)或修订版均不适用于本标准，然而，鼓励根据本标准达成协议的各方研究是否可使用这些文件的最新版本。凡是不注日期的引用文件，其最新版本适用于本标准。 GB/T 12241安全阀 一般要求(GB/T 12241—2005，ISO 4126-1：1991，MOD) GB/T 12243 弹簧直接载荷式安全阀(GB/T 12243—2005，JIS B 8210—1994，MOD) 3术语 GB/T 12241中术语的定义适用于本标准。 3.1通用术语 3.1.1 压力释放装置pressure relief device 一种用来在压力容器处于紧急或异常状况时防止其内部介质压力升高到超过预定最高压力的装置。 3.1.2 动作性能及排量试验operational characteristics and flow capacity testing 用来确定压力释放装置的动作性能和实际排放能力的试验。 3.1.3 在用试验 in-service testing 当压力释放装置安装在系统上正在对系统实施保护时，单独利用系统压力或配合使用辅助开启装置或其他压力源以确定其某些或全部工作特性的试验。 3.1.4 工作台上定压试验bench testing 为确定压力释放装置的整定压力和关闭件密封性而在一个加压系统上进行的试验。 3.2压力释放装置类型 3.2.1 重闭式压力释放装置reclosing pressure relief device 一种在动作后再行关闭的压力释放装置。 a) 安全阀safety valve 一种自动阀门，它不借助任何外力而利用介质本身的力来排出一额定数量的流体，以防止压力超过额定的安全值。当压力恢复正常后，阀门再行关闭并阻止介质继续流出。 b) 直接载荷式安全阀direct-loaded safety valve 一种仅靠直接的机械加载装置如重锤、杠杆加重锤或弹簧来克服由阀瓣下介质压力所产生作用力的安全阀。 c) 带动力辅助装置的安全阀 assisted safety valve 该安全阀借助一个动力辅助装置，可以在压力低于正常整定压力时开启。 d) 带补充载荷的安全阀supplementary loaded safety valve 这种安全阀在其进口压力达到整定压力前始终保持有一个用于增强密封的附加力。该附加力(补充载荷)可由外部能源提供，而在安全阀进口压力达到整定压力时应可靠地释放。补充载荷的大小应这样设定，即假定该载荷未能释放时，安全阀仍能在其进口压力不超过国家法规规定的整定压力百分数的前提下达到额定排量。 e) 先导式安全阀pilot-operated safety valve 一种依靠从导阀排出介质来驱动或控制的安全阀。该导阀本身为直接载荷式安全阀。 f) 真空安全阀vacuum relief valve 一种设计用来补充流体以防止容器内过高真空度的安全阀，当正常状况恢复后又重新关闭而阻止介质继续流入。 3.2.2 非重闭式压力释放装置non-reclosing pressure relief device 一种在动作后保持开启的压力释放装置。 a) 爆破片装置rupture disk device 一种由装置进出口静压差驱动的非重闭式压力释放装置，其功能系通过承压片的爆破而实现。 b) 折断销装置breaking pin device 一种由进口静压力驱动的非重闭式压力释放装置，其功能系通过承压件支承销承载截面的折断而实现。 c) 弯折销装置buckling pin device 一种由进口静压力驱动的非重闭式压力释放装置，其功能系通过承压件支承销承载截面的弯折而实现。 d) 剪切销装置shear pin device 一种由进口静压力驱动的非重闭式压力释放装置，其功能系通过承压件支承销承载截面的剪切而实现。 e) 易熔塞装置fusible plug device 一种非重闭式压力释放装置，其功能系通过一个用具有适当熔点的材料制成的塞子的屈服或熔化而实现。 3.3安全阀的特性尺寸 3.3.1 排放面积discharge area 阀门排放时流体通道的最小截面积。 3.3.2 流道面积 flow area 阀进口端至关闭件密封面间流道的最小横截面积。 3.3.3 流道直径 flow diameter 对应于流道面积的直径。 3.3.4 帘面积curtain area 当阀瓣在阀座上方升启时，在其密封面之间形成的圆柱面形或圆锥面形排放通道面积。见图1。 3.3.5 开启高度lift 阀瓣离开关闭位置的实际行程。 3.3.6 额定开高rated lift 使阀门达到其额定排量的设计开高。 3.3.7 密封面斜角seat angle 阀门轴线与密封面间的夹角。平面密封阀门的密封面斜角为90°。 3.3.8 密封面积seat area 由密封面平均直径确定的面积。 3.3.9 密封面平均直径seat mean diameter 阀瓣与阀座接触面的平均直径。 3.4非重闭式压力释放装置的特性尺寸 3.4.1 净流通面积net flow area 非重闭式压力释放装置动作之后决定流量的面积。一个爆破片的(最小)净流通面积是其完全破裂后的计算净面积，它带有适当的允差，因为爆破片的某些结构件可能减小其净流通面积。 3.5压力释放装置的动作和排量特性 3.5.1 整定压力 set pressure 安全阀在运行条件下开始开启的预定压力，在该压力下，在规定的运行条件下由介质压力产生的使阀门开启的力同使阀瓣保持在阀座上的力相互平衡。 3.5.2 超过压力 overpressure 超过安全阀整定压力的压力增量，通常用整定压力的百分数表示。 3.5.3 回座压力 re-seating pressure 安全阀排放后阀瓣重新与阀座接触，即开启高度变为零时的压力。 3.5.4 启闭压差blowdown 整定压力同回座压力之差，以整定压力的百分数或以压力单位表示。 3.5.5 排放压力relieving pressure 整定压力加超过压力。 3.5.6 额定排放压力flow-rating pressure 标准或规范规定的排放压力上限值，是测量压力释放装置排量时的进口静压力。 3.5.7 背压力 back pressure 由于在排放系统中存在压力而在压力释放装置出口产生的静压力。 3.5.8 排放背压力built-up back pressure 由于介质流经压力释放装置进入排放系统而在该装置出口处产生的压力。 3.5.9 附加背压力superimposed back pressure 压力释放装置即将动作前在其出口处存在的压力，是由其他压力源在排放系统中引起的。 3.5.10 冷态试验差压力cold differential test pressure 安全阀在试验台上调整到开始开启时的进口静压力，该压力包含了对背压力和/或温度等运行条件所作的修正。 3.5.11 密封试验压力tight test pressure 进行密封试验时的进口静压力，在该压力下测量通过关闭件密封面的泄漏率。 3.5.12 爆破压力 burst pressure 当爆破片装置动作时，其进口静压力。 3.5.13 爆破片装置的规定爆破压力 specified burst pressure of a rupture disk device 爆破片装置升高的进口静压力，在规定的温度下爆破片设计在该压力爆破。 3.5.14 折断压力breaking pressure 当折断销装置、弯折销装置或剪切销装置动作时.其进口静压力。 3.5.15 一次压力primary pressure 压力释放装置进口压力。 3.5.16 二次压力 secondary pressure 在安全阀的实际排放截面与出口间的通道中存在的压力。 3.5.17 前泄压力simmer pressure 一个低于安全阀整定压力的进口静压力，在该压力下，安全阀关闭件密封面间发生可由听觉或视觉感知的介质泄出，但没有可测量的排量。前泄压力仅适用于可压缩介质用的安全阀。 3.5.18 理论排量theoretical relieving(discharge)capacity 其流道最小截面积等于安全阀流道面积或等于非重闭式压力释放装置净流通面积的理想喷管的计算排量，以重量单位或容积单位表示。 3.5.19 实测排量 measured relieving(discharge)capacity 在额定排放压力下测量的压力释放装置排量，以重量单位或容积单位表示。 3.5.20 额定排量rated relieving capacity(certified discharge capacity) 实测排量中由适用的规范或标准允许用作压力释放装置应用基准的部分。 3.5.21 当量计算排量equivalent calculated capacity 当压力、温度或介质等使用条件与额定排量的适用条件不同时，压力释放装置的计算排量。 3.5.22 排量系数coefficient of discharge 实测排量同理论排量的比值。 3.5.23 额定排量系数rated coefficient of discharge 额定排量同理论排量的比值。 3.5.24 频跳 chatter 安全阀阀瓣快速异常地来回运动，运动中阀瓣接触阀座。 3.5.25 颤振 flutter 安全阀阀瓣快速异常地来回运动，运动中阀瓣不接触阀座。 3.5.26 基准状况 reference conditions 由适用的标准或由试验各方间的协议规定的试验介质状况，可用来统一排量试验的结果。 平面密封阀门 帘面积=πDL 锥面密封阀门 帘面积=πB(D+DB)/2 锥面密封阀门 帘面积=πB(D+DB)/2 锥面密封阀门 帘面积=πB(D+DB)/2 球面密封阀门 帘面积=πB(D+DB)/2 球面密封阀门 帘面积=πB(D+DB)/2 L=开启高度 D=阀座阀瓣接触面最小直径 DB=锥面通道另一直径 B=锥面通道斜高 θ=密封面斜角 R=半径 注：帘面积系排放面积，陈非阀瓣达到足够开高使流道面积成为通道最小截面积。 图1 安全阀帘面积的典型示意图 4总则 4.1本标准试验的测量偏差规定如下：对于排量试验，最终排量测量的偏差应不超过测量值的±2.0％；对于动作性能试验，压力测量的偏差应不超过测量值的±0.5％；对于在用试验及工作台上定压试验，压力测量的偏差应不超过测量值的±1.0％。 4.2进行本标准规定的试验，要求试验装置具备试验所要求的压力和足够容量。进行动作性能和排量试验时试验容器的直径，当用蒸汽或气体试验时应至少为压力释放装置进口通径的10倍；当用液体试验时，应至少为4倍。应按试验程序(见5.4)的要求保持试验运行条件，试验持续时间应满足在稳定状况下取得必要的动作性能和排量数据的需要。 4.3现场安装及/或非正常运行条件可能会对压力释放装置的功能产生不利影响。评估压力释放装置在这类条件下的适用性和可靠性不属于本标准的范围。 4.4如果压力释放装置试验所用介质的温度同装置在实际使用时承受的温度之间存在较大的差别，其实际使用时的功能特性如开启压力、启闭压差和爆破压力等将不同于试验得出的特性。考虑这些不同而对试验条件下的压力释放装置作适当修正的内容也不属于本标准的范围。 4.5本标准提供推荐的试验程序和测试仪表。其他的试验程序和测试仪表只要能证明具有至少与本标准要求等同的精度和可靠性，则可以使用。如果要使用其他的程序和仪表，则必须在试验之前征得试验有关各方的书面同意。 4.6应按照测量和计算来对试验结果作出报告。只有当试验完全符合本标准的强制性要求时，才可以被指认为按照本标准进行的试验。 4.7试验的有关方应对管道系统和部件的设计和超压保护、试验中压力释放装置的安全排放以及通常伴随着排放的高噪声等给予特别的考虑，以保证试验装置满足最低强制要求。 4.8应达成协议的事项 试验各方应在进行试验之前就下列事项达成协议： a)试验目的； b) 试验场所，试验各方，试验和试验监督人员； c) 在额定排放压力下试验流体的基准状况； d)试验所用的测试方法、仪表和设备(仪表的校准应按5.1.2)； e)被试装置的数量、通径、类型、状况、来源、整定压力和预期排量； f) 书面的试验程序，该程序应包括为满足试验目的所应进行的观测和所应记录的读数。 4.9试验和试验监督试验人员的资格和职责 试验和试验监督人员应接受过热力学和流体力学的正规教育，并具有流体流量测量的实际经验。试验监督人员还应具有监督试验的经验。所有从事会影响试验结果的操作的人员应完全了解进行这些操作的正确方法。 试验和试验监督人员应负责保证书面的试验程序得到遵循，并对试验仪表已按5.1.2要求进行校准负责。 5压力释放装置动作性能及排量试验 5.1试验装置和仪表 5.1.1试验装置的布置按图2至图7及图9所示。测量应符合5.2的要求。 5.1.2仪表校准 试验中使用的每一台仪表以及备用仪表都应有编号或作其他明确标记。每一仪表依照其类型不同应按本节中概述的下列要点进行校准。有关的仪表校准记录应保存以供有关方面查阅。 5.1.2.1压力测量仪表 压力测量仪表的精度等级不应低于0.5级。压力测量系统应包括两套压力测量仪表，以便在试验中进行互校。应按国家有关规程对压力测量仪表进行校准。国家规程未规定的压力指示或记录装置的校准方法应得到有关方面的认可。 5.1.2.2温度测量仪表 温度测量仪表的分辨率不应低于0.5℃。温度测量系统应包括两套温度测量仪表，以便在试验中进行互校。应按国家有关规程对温度测量仪表进行校准。国家规程未规定的温度指示或记录装置的校准方法应得到有关方面的认可。 5.1.2.3开高测量仪表 开高测量仪表的分辨率应不低于0.02 mm。应在每次试验或一系列试验的前后对其精度进行检查。 5.1.2.4重量秤 在试验程序中用来称量冷凝液重量的重量秤，其指示部件的最小刻度值应小于或等于预期载荷的0.25％。用于本标准试验的重量秤应在每次或一系列试验之前按国家有关规程在足够的点位上进行校准，以保证其在预期使用范围内的精度。 5.1.2.5蒸汽热量计 蒸汽热量计应分别在其安装之时和在不超过6个月的规定周期内用蒸汽进行校准。当测量结果显示其读数有明显错误时或在重新安装后，应再进行校准。 5.1.2.6流量计组合 对任何类型流量计(见5.2.4)的校准应包括流量计上游和下游侧的实际管道和所有附件，附件包括控制阀、试验容器以及容器同阀门的连接件。这种校准应通过比较的方法在执行正式试验之前完成，即把流量测定值同由预先校准的流量计装置测得的值进行比较，而后者的校准系借助原始的装置或机构来完成。有关预先校准的流量计装置的协议应使最终总体试验结果的偏差在±2.0％以内。校准应在相应于对比装置的最小、中间和最大流量下进行。对于具有不同进口连接形式的阀门，其连接件应在制造或采购时由试验室人员进行校准。此外，流量计装置应如上述每5年至少进行一次再校准。这种再校准应包括使用至少两种尺寸的连接件。应保存校准记录并提供有关方面审核。若对设备作改变，应评估这种改变可能对系统校准产生的影响，当认为必要时应进行新的校准。 5.1.3试验中的调整 当在采集数据时，不应对压力释放装置作任何调整。在试验条件发生任何改变或偏离后，应给予足够的时间使流量、温度和压力达到稳定后再采集数据。 5.1.4试验记录和试验结果 试验记录应包括对试验对象的所有观察、测量、仪表读数和仪表校准记录(当需要时)。原始试验记录应由进行试验的机构保管，其保管期限不少于5年。所有试验记录的副本应提交试验各方。修正及修正值应分别载入试验记录。应按本标准5.6的规定作试验汇总报告。 5.1.5测量误差 应进行预备试验来确定，使用规定的仪表和程序能够满足4.1中对最终排量测量所规定的误差极限。还应进行试验后的误差分析，除非试验各方同意并证实，规定的仪表和程序包括数据的离散性是按试验规范来使用和执行的，从而确认预备试验确定的误差在试验后仍然有效。误差确定应由试验室形成文件以供审核。 5 2测量方法 5.2.1大气压测量 大气压应使用气压表测量。在进行包含排量的计算时，若压力释放装置的额定排放压力等于或高于0.15 MPa(表压)，则使用试验当地的平均大气压即可满足本规范的精度要求。在这种场合，记录的压力可以是平均大气压。 5.2.2温度测量 a)根据操作条件，温度测量可以采用玻璃管式液体温度计、双金属温度计、电阻式温度计或热电偶。除玻璃管式液体温度计必须插到套管中外，所有上述温度计可以直接插入管道中，也可插到套管中。当温度低于150℃时，宜将测温装置直接插入管道而不附加套管。 b) 当进行任何温度测量时，应采取下列措施： 1)除被测介质外，测温装置同外界不应有因辐射或传导产生的较大热传递。 2) 插入点的紧邻部位和测温装置的外露部分应隔热。 3)对于小直径管道，测温装置的插入深度应穿过管道中心线；当管道直径超过300 mm时，应插入到介质流中至少150 mm深处。 4)在输送可压缩流体的管道上，只要可能，测温装置应安装在进行任何流量测量时最大介质流速不超过30 m/s的地方。如果不可能这样安装，则可能需要将温度读数校正到适当的静温或全温。 5) 测温装置的插入位置应使其测量的温度正如在试验布置中描述的那样能代表流动介质的温度。 c) 当使用玻璃管式水银温度计测量温度时，该温度计应有一个带刻度的杆。当被测温度同环境温度的差值大于5℃且水银部分露出时，应作露出杆修正，或使用露出杆式温度计。 d) 当使用温度计套管时，套管应是薄壁的，其直径应尽可能小。套管外表应无腐蚀或杂物。套管内应充以适当的流体，但不宜采用水银。因为水银的蒸发压很低，会给人员健康带来严重危害。当然，如果为此目的而采用了水银，则必须采取适当的预防措施。 e)若采用热电偶，则应具有焊接的热端，且必须连同其外接导线一起在预期的使用范围进行校准。热电偶应采用适合于被测温度和介质的材料构成。其电动势应利用电位计或毫伏表来测定。热电偶的冷端应利用一个冰浴(参照标准器)或通过在电位计加装补偿电路而构成。 5.2.3压力测量 a)测压点应布置在流动基本上平行于管壁或容器壁的区域。当测量小于0.1MPa的静压差时，可以采用液体压力计。 b)试验容器的压力应为通过图2所示取压口测量的静压力。 c) 背压力应为通过图3、图5及图6所示取压口测量的静压力。 d) 如果在测压点和压力计之间存在水位差或其他液位差，则应对压力读数作适当修正。 5.2.4流量测量 a)测量压力释放装置排量的方法有： 1) 亚音速推断式流量计，包括孔板、流量喷嘴和文丘里管； 2) 音速推断式流量计，包括塞流喷嘴； 3) 直接收集排放介质或其冷凝液的容积法或重量法。 h) 测量压力释放装置排量应视情况分别采用下列方法： 1)背压为大气压时的蒸汽流量，采用上述a)1)或a)3)方法： 2)背压高于大气压时的蒸汽流量，采用上述a)1)方法； 3) 背压为大气压时的空气或气体流量，采用上述a)1)或a)2)方法； 4)背压高于大气压时的空气或气体流量，采用上述a)1)方法； 5)背压为大气压时的液体流量，采用上述a)1)或a)3)方法； 6)背压高于大气压时的液体流量，采用上述a)1)方法。 注：本节并不排除在背压高于大气压时用音速推断式流量计测量压力释放装置排量的试验。然而，由于通过这类流量计的压降很大，这样的试验也许是不可行的。 c)一次测试元件 1)一次测试元件应置于被试压力释放装置进口的上游侧。安装要求及仪表位置如图2所示。孔板孔径同管道内径的比率应在0.2到0.7之间。一次测试元件应在试验之前进行检查以确认其洁净和未受损伤。 2) 一次测试元件前后的压差和流体温度应利用连接在图2所示位置的仪表进行测量。 3) 在一次测试元件前面应有足够长的直管段，以保证在靠近元件的流道内有一个相当均匀的流速分布。为保证压力测量可靠，在一次测试元件的出口侧也应有与进口管道同样公称尺寸的足够长的直管段。 4) 在排量测量过程中流动应保持稳定，差压计上显示的总脉动值(双倍振幅)不应大于被测差压的2％。当脉动值较大时，应消除脉动的起因，试图就仪表本身来减少脉动是不允许的。 5)应采取措施避免使用通常会导致不稳定状态的过湿蒸汽。当用蒸汽进行试验时，应使用节流式热量计测量蒸汽干度(参见5.2.5)。 5.2.5蒸汽干度测量 流动蒸汽的于度应采用节流式热量计进行测量。热量计的安装如图2和图3所示。其蒸汽取样管也可直接安装在容器上，只要取样管伸入到压力释放装置进口喷嘴中心线正下方的流道中，同时不低于试验容器的水平中心线。
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