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1、JPS B*A225 Ab 4933608 0020549 9 siil - JIS .- a JAPANESE INDUSTRIAL STANDARD Measuring Methods for Coefficient of Discharge of Safety Valves Translated and Published Japanese Standards Association UDC 621.646.4 . - Printed in Japan 14 S Copyright Japanese Standards Association Provided by IHS under
2、license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- J I S B*225 8b I 4933608 0020550 5 I In the event of any doubt arising, the original Standard in Japanese is to be final
3、authority. Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- J I S B*8225 8b m 4933608 0020553 7 1 UDC 621,6
4、46.4 1. Scope JAPANESE INDUSTRIAL STANDARD J I S Measuring Methods for Coefficient B 8225-1986 . of Discharge of Safety Valves This Japanese Industrial Standard specifies measuring methods for coefficient of discharge of safety valves for steam and gas, hereinafter referred to as the “safety valves“
5、. Remark: In this Standard the units and numerical values shown in and calculation formulae are in accordance with the International System of Units (SI) and, appended for informative reference. 2. Definitions For the purposes of this Standard following definitions apply: (1) safety valve The valve
6、which actuates automatically when the pressure at the inlet side has become the preliminarily definite pressure, returns again to the normal condition when the pressure lowers, and has the capability to exhaust the nominal discharge amount. measured experimentally to be expressed by kgf/h kg/h). (2)
7、 discharge amount The discharge amount of fluid (steam, air or gas) (3) theoretical discharge amount The calculated discharge amount, which is the amount specified in 4.2.2 relating to each fluid. (4) nominal discharge amount The discharge amount guaranteed for each safety valve which is specified i
8、n 5. Applicable Standards: 0 JIS B 7503-Dial Gauges Reading in 0.01 mm JIS B 8210-Spring Loaded Safety Valves for Steam Boilers and JIS C 1602-Thermocouples JIS C 1604-Resistance Thermometer Sensors Pressure Vessels JIS Z 8704-Electrical Methods of Temperature Measurements JIS Z 8705-Method of Tempe
9、rature Measurement by Liquid-in-Glass JIS Z 8762-Measurement of Fluid Flow by Means of Orifice Plates, Thermometers Nozzles and Venturi Tubes Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007
10、 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- J I S B*8225 86 E 4933608 0020552 9 2 B 8225-1986 coefficient of discharge discharge amount. The ratio of discharge amount to theoretical nominal coefficient of discharge discharge amount which is in accordance with
11、the specification of 4.2.3. The coefficient to be applied to nominal diameter of valve seat opening valving element with the valve seat (Refer to Appendix Attached Figure of JIS B 8210). The inner diameter of fitting surface of - lift The travelling amount of valve element or valve stem in axial dir
12、ection from the closed position of valve to the opened position of valve during discharge of safety valve. valve seat angle In the flat seat valve, the valve seat angle becomes 90“ (Refer to Appendix Attached Figure of JIS B 8210). The angle included by valve axis and valve seat face. valve seat are
13、a opening. The area formed according to diameter of valve seat discharge area safety valve which is used for calculation of nominal discharge amount (Refer to Appendix Attached Figure of JIS B 8210). The area to determine the flow rate passing through the area of gorge The area of narrowest part of
14、nozzle from fluid inlet until valve seat face. Relating to lower-guide valve, the area subtracted by the areas of vane and shaft. area becomes the discharge area (Refer to Appendix Attached Figure of JIS B 8210). In a whole amount type safety valve, the gorge determination pressure for nominal disch
15、arge amount determine the nominal discharge amount which is the pressure specified in Appendix of JIS B 8210. The pressure to back pressure following two pressures: The pressure at outlet side of safety valve. There are (a) The pressure generated at outlet side of safety valve by resistance of disch
16、arge side when the safety valve has started discharge. The pressure existing at discharge side already before discharge of safety valve. (b) (15) nominal diameter The nominal diameter expressing the size of safety valve is expressed by diameter of fluid inlet and is in accordance with the specificat
17、ion of 3. (3) of JS B 8210. 3. Tests 3.1 Test Methods 3.1.1 gas clear in physical value and respective back pressure side, the atmospheric pressure. Fluid for Test The fluid to be used for test shall be steam, air or Copyright Japanese Standards Association Provided by IHS under license with JSALice
18、nsee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- JIS B*8225 86 m 4933608 0020553 O m 3 B 8225-1986 3.1.2 Type of Test The type of test and its application shall be as follows: (1) Test A Rel
19、ating to those of the same design series (), select three kinds of representative nominal diameters, measure actual discharge amounts of nine pieces in total respectively at three different pressures, and determine the nominal coefficient of discharge, hereinafter referred to as the llK;ll. Its Kd m
20、ay be used for every pressure and nominal diameter relating to every one of this design series. range of nominal diameters is not more than six kinds, it may be performed on nominal diameters of two kinds. design series, measure the actual discharge amounts at different pressures respectively to det
21、ermine Kd. design. However, in the case where the (2) Test B Relating to four pieces of the same diameter of the same Its Kd may be used for all pressures of nominal diameters of this (3) Test C Select three kinds of nominal diameters representative to the same design series and measure the actual d
22、ischarge amounts at the same pressure to determine Kd. diameters of this design. Note (l) Its K d may beused to the tested pressure relating to all nominal It means safety valves of the same design conception for example a group of safety valves to be expressed by style number or the like constituti
23、ng of a series nominal diameters relating to each nominal pressure. 3.2 Instruments and Measuring Methods - 4 3.2.1 Measurement of Atmospheric Pressure Measure by means of a suitable instrument of not more than 0.25 mmHg C33.3 Pa) in instrumental error. the measured value reported from the meteorolo
24、gical observatory of each district performed with the height correction may be used as the atmospheric pressure. 3.2.2 Measurement of Temperature The measurement of temperature shall be as follows: However, e The temperature should preferably be in accordance with the instrument and measuring method
25、 specified in JIS Z 8705, JIS C 1602, JIS C 1604 and JIS Z 8704. For measurement of temperature, . use the thermometer certified by of ficial organization or a thermocouple or resistance bulb calibrated by the thermometer certified by official organization relating to the temperature scale in its us
26、ing range and insert into the piping or thermometer cylinder to measure. However, in the case of measuring a temperature of not more than 150C, it is preferable to attach the temperature detector in the piping directly without using thermometer cylinder. Copyright Japanese Standards Association Prov
27、ided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- - J I S 8*8225 86 4933608 0020554 2 4 B 8225-1986 The thermometer cylinder shall be clean and free from
28、 rust, and, inserted with a suitable liquid having a boiling point not lower than the highest value of temperature to be measured into its inner part. Further, the thickness shall be made as thinner as possible in the safe stress range and also its inner, as smaller as possible. The temperature at s
29、afety valve inlet shall be measured at the positions shown in Fig. 1 and Fig. 2. temperature measuring point to the specimen valve is not more than five times the piping diameter and is free from harmful variation in piping diameter, this temperature may be treated as the temperature of fluid passin
30、g the throttling mechanism. In cases where the piping length from the The measuring of temperature of fluid passing the throttling mechanism shall be in accordance with the specifications of JIS Z 8762. Cautions to TemDerature Measurement (6.1) General Cautions General cautions shall be as follows:
31、Restrict the heat amount given by conduction or radiation to the temperature measuring device from substances other than those to be measured in temperature to the minimum limit. The part near the inserting point of thermometer and the exposure part of thermometer cylinder shall be heat-insulated. I
32、n the case of measuring the temperature of fluid in a small bore tube, the detecting part of thermometer shall be inserted more deeply than the centre of piping. Further, in the case of a large bore tube exceeding 300 mm, the detecting part of thermometer shall be inserted by 150 mm at least. (d) In
33、 the case of measuring the fluid temperature, the detecting part of temperature measuring device shall not be placed at a portion where the flow is congested. in cases of using mercury-in glass thermometer shall be as follows: (6.2) Cautions in Cases of Using Mercury-in Glass Thermometer Cautions (a
34、) The thermometer kept in a metal case shall not be used. (b) Correction to exposed part shall be in accordance with 9. of JIS Z 8705. exposed part shall be so heat-insulated that the influence from those other than mercury column of main thermometer is not received as far as possible. Further, the
35、mercury reservoir of thermometer for correction of Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- - JIS B
36、*A225 Ab W 4733608 0820555 4 3.2.3 follows: (1) 5 B 8225-1986 (6.3) Cautions in Cases of Using Thermocouple using thermocouple shall be as follows: Cautions in cases of (a) The temperature-measuring contact point shall be complete and relating to temperature graduation in using range together with c
37、ompensation conductor, be authorized. (b) The material of thermocouple shall be suitable to fluid and temperature to be measured. (c) The thermocouple specified in JIS C 1602 shall be used. (3) Measurement of Pressure The measurement of pressure shall be as As to measurement of pressures, for measur
38、ing of static pressure not more than 1 kgf/cm2 (0.1 MPal use a liquid column meter, and for pressure or differential pressure exceeding 1 kgf/cm2 CO.1 MPa use a Bourdon tube pressure gauge completed with calibration. The pressure gauge shall be divided into graduations within 1 % of the maximum grad
39、uation, in scale. The Bourdon tube pressure gauge shall be used in the range within -$- of the maximum graduation. Pressure measuring positions shall be arranged in the portion where the flow is practically parallel to walls of piping and container. The safety-valve inlet pressure shall be the stati
40、c pressure measured at positions of pressure gauge shown in Fig. 1 and Fig. 2. In the case where water or other liquid column exists between the pressure-measuring point and the pressure gauge, the correction to reading of pressure shall be conducted. 3.2.4 Measurement of Flow Rate For measurement o
41、f flow rate, the orifice 0 specified in JIS Z 8762 shall, as a rule, be used and, as follows. Further, in cases where it is impossible to use orifice, the nozzle specified in JIS Z 8762 may be used. (1) In the case where a flow-rate measuring method other than that specified in JIS Z 8762 is applied
42、, the attachment, procedures and calculation of instantaneous flow rate shall be agreed upon between the parties concerned with delivery. Selection of method, selection of flowmeter, details of its use, etc. shall be agreed upon between the parties concerned with delivery prior to test, The orifice
43、shall comply with the following specifications: (2) (3) (a) The orifice shall be set at upstream side of specimen valve inlet. The setting conditions and positions are shown in Fig. 1 and Fig. 2. Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/11
44、11111001, User=Wing, Bernie Not for Resale, 03/14/2007 08:45:04 MDTNo reproduction or networking permitted without license from IHS -,-,- JIS B*8225 86 4933b08 0020556 b 6 B 8225-1986 (b) The throttling aperture diameter of orifice shall be of such that the differential pressure before and after the
45、 orifice is not less than 100 mm in water column. (c) The maximum differential pressure before and after the orifice should, preferably, be not more than 2500 mm in water column. (d) Throttling diameter ratio of orifice to piping diameter shall not exceed 0.7. (e) The orifice shall be confirmed that
46、 it is clean through during the test period according to a suitable method. (4) (5) 3.2.5 (1) (3) (4) (5) The differential pressure before and after the orifice and the temperature of fluid shall be measured with arranging the instruments at the positions shown in Fig. 1 and Fig. 2. Cautions of 3.2.
47、3 applies to pressure measurement, and cautions of 3.2.2, to temperature measurement respectively. The length of straight tube at the upstream side of orifice shall be taken so sufficiently that the approaching flow to the orifice becomes regular and uniform flow velocity distribution (Refer to JIS
48、Z 8762). Further, depending upon the agreement, a rectifier may be used at upstream side of straight pipe part. In order to secure a reliable pressure measuring, a sufficiently long straight tube part of the same diameter shall be provided at the downstream of the orifice (Refer to JIS Z 8762). In the case of measuring of flow rate, the flow shall be stabilized as far as possible and the measuring differential pressure of liquid column meter, free from pulsation (total amplitude) exceeding 2 %. Further, in case where pulsation exceeding 2 % exists, the source shall be co