This standard specifies the mandatory requirements for materials, technical requirements, test methods and acceptance rules for gas cylinder pressure reducers used in welding, cutting and similar processes. This standard applies to single-stage and double-stage gas cylinder pressure reducers used in welding, cutting and similar processes. This standard must be used in conjunction with the recommended standard GB 7899-87 when conducting factory inspection, type inspection or other relevant national sampling inspections of pressure reducer products. JB 7496-1994 Safety Specification for Gas Cylinder Pressure Reducers for Welding, Cutting and Similar Processes JB7496-1994 Standard download decompression password: www.bzxz.net

Machinery Industry Standard of the People's Republic of China
JB7496-94
Safety Specifications for Gas Cylinder Pressure Reducers for Welding, Cutting and Similar Processes
Published in 1994 - 09 08
Implementation in 1995-0501
Published by the Ministry of Machinery Industry of the People's Republic of China Machinery Industry Standard of the People's Republic of China
Safety Specifications for Gas Cylinder Pressure Reducers for Welding, Cutting and Similar Processes 1 Subject Content and Scope of Application
JB7496-94
This standard specifies the mandatory requirements for materials, technical requirements, test methods and acceptance rules for gas cylinder pressure reducers for welding, cutting and similar processes in terms of safety assurance
This standard applies to single-stage and double-stage gas cylinder pressure reducers for welding, cutting and similar processes (hereinafter referred to as pressure reducers). This standard must be used in conjunction with the recommended standard GB7899-87 when it is used for factory inspection, type inspection or other relevant national sampling inspection of pressure reducer products.
2 Reference standards
GB7899-87 Gas cylinder pressure reducers for welding, cutting and similar processes 3 Terms and symbolsbZxz.net
Terms and symbols used in this standard shall be in accordance with the provisions of GB7899-87 4 Materials
4.1 The copper content of materials in contact with acetylene or gases with similar chemical properties shall not exceed 70% (m/m). When silver-copper solder and copper solder alloy are used, the welding thickness of the filler metal shall not exceed 0.3mm, and the silver content in the solder shall not exceed 43% (m/m), and the copper content shall not exceed 21% (m/m)
Note: % (m/m) indicates mass percentage. 4.2 All parts in contact with oxygen shall be free of grease. 5 Technical requirements
5.1 Mechanical strength
5.1.1 Structural strength
The high-pressure chamber and low-pressure chamber of the pressure reducer shall not have permanent deformation after a water pressure test of 5 minutes under the pressure specified in Table 1. Table 1
When P2<1
Approved by the Ministry of Machinery Industry on September 8, 1994
When P2≥1
Implemented on May 1, 1995
JB1496-94
512 Safety
When the low-pressure chamber of the pressure reducer or the intermediate chamber of the two-stage pressure reducer is directly connected to the gas cylinder filled with high-pressure gas, for the pressure reducer with a rated inlet pressure of 15MPa, the high-pressure gas should be cut off or safely discharged, and for the pressure reducer with a rated inlet pressure less than 3MPa, the high-pressure gas should be cut off.
5.2 Safety discharge device
The pressure reducer with a rated inlet pressure of 15MPa should be equipped with a safety discharge device, which should meet the following requirements. a. It should be sealed when the outlet pressure is not greater than 1.3p2; b. It should be able to exhaust when the outlet pressure is greater than 1.3p2 and less than the safe discharge pressure; c. The safe discharge flow rate should not be less than the rated flow rate Q1 of the pressure reducer. 5.3 Explosion safety
All parts of the oxygen pressure reducer should be cleaned of grease before assembly. After assembly, they should be able to withstand 20 continuous impacts of rated inlet pressure oxygen without ignition or internal damage similar to burning. 5.4 Pressure gauge
5.4.1 Mark
The red "Oil-free" word or the following oil-free mark should be marked on the dial of the pressure gauge measuring oxygen pressure. 5.4.2 Energy release
When the spring tube breaks, the exhaust hole on the back of the pressure gauge should be able to discharge the leaked gas in the direction away from the front of the pressure gauge, and the pressure gauge glass should be intact.
6 Test method
6.1 Test conditions
The test shall be carried out at 20±5℃. When this condition cannot be met, the measured gas volume flow rate shall be converted to the volume flow rate at 20℃.
6.1.1 General requirements for test equipment
The diameter of all pipelines and valves controlling the flow rate of the test equipment must be larger than the inlet diameter of the pressure reducer to be tested. 6.1.2 Test gas
The test generally requires oil-free air or nitrogen. Oxygen pressure reducers can be tested with oxygen. Stock
When the test gas is inconsistent with the gas used when the pressure reducer is working, the measured flow rate shall be converted to gas flow rate according to the provisions of Appendix A (Supplement).
6.1.3 Flow measurement
The accuracy level of the instrument for measuring gas volume flow rate shall not be lower than Class 2.5. 6.1.4 Pressure measurement
The accuracy level of the instrument for measuring pressure shall not be lower than Class 1.0. 6.2 Mechanical strength test
6.2.1 Structural strength test
JB7496-94
Plug the installation holes of the safety discharge device and pressure gauge of the pressure reducer with screw plugs, replace the diaphragm of the pressure reducer with metal sheets, and conduct a 5-minute water pressure test on the low-pressure chamber and the high-pressure chamber according to the pressure specified in Table 1. Then check that the size and shape should not change. 6.2.2 Safety test
Plug the installation holes of the safety discharge device and pressure gauge of the pressure reducer with screw plugs, make the inlet pressure pl, the outlet pressure P2, close the inlet, and gradually apply a steadily increasing pressure to the low-pressure chamber through the outlet until p1. During the test, there should be no leakage in the pressure reducer with a rated inlet pressure of less than 3MPa. The spring cover of the pressure reducer with a rated inlet pressure of 15MPa should be able to withstand this pressure and no debris should fly out from the inside. 6.3 Safety discharge device test
The test can be carried out on the pressure reducer or on special equipment. When it is carried out on the pressure reducer, the valve of the pressure reducer should be opened or removed.
During the test, apply a gas source pressure of 1.3p2 to the safety discharge device through the inlet. Check with a leak detection solution and no bubbles should appear. Continue to increase the pressure until bubbles begin to appear in the safety discharge device, and record the pressure at this time. This pressure should be less than pRV. Increase the pressure again until the safety discharge device is fully opened, and measure the flow rate discharged at this time. If it is less than Q, continue to increase the pressure to PRV, and then measure QRy. Reduce the pressure until the safety discharge device is closed. The pressure at this time should be greater than p2
6.4 Explosion safety test
The test is carried out using the device shown in Figure 1 (schematic diagram). The aperture of the quick-opening valve should not be less than 3mm, and the connecting pipeline between it and the pressure reducer to be tested should be as short as possible. During the test, the regulating handle of the pressure reducer should be completely loosened to keep the pressure reducer in the closed state. The time for the test pressure to rise from atmospheric pressure to p value is 20ms. The test gas source uses industrial gaseous oxygen (hydrogen-free) with an inlet pressure of p and a purity of not less than 99.5% (volume percentage), and is preheated to 603℃. The pressure shock wave generated by oxygen is sent from the inlet for shock. Each shock lasts for 10s, and the shock interval is 30s. Each group of tests is subjected to 20 shocks in total. During the interval, the test pressure should be released to atmospheric pressure by the quick-opening valve. The pressure drop in each group of tests shall not exceed 3% of the p1 value.
For two-stage pressure reducers, the first decompression chamber should also be tested. Pressure instrument
183838
Temperature regulator
Heating system
6.5 Pressure gauge inspection
6.5.1 Marking inspection
Visual inspection.
6.5.2 Energy release test
Oxygen temperature maintenance system
Control thermometer
Figure 1 Explosion test device (schematic diagram)
Tested pressure reducer
Protection system
Connect the pressure gauge to the gas source to reserve energy E=pV. Then suddenly exhaust the gas in the gauge case. The gas source gas should be continuously replenished during exhaust. Among them: p is 1.5 times the upper limit of the measurement range of the pressure gauge. If the calculated value is less than 4MPa, take 4MPa: V is the approximate value of the spring tube capacity of the pressure gauge
JB7496-94
Skin Note: If a pressure chamber is used to simulate the spring tube at the inlet end of the pressure gauge, the diameter of the inlet hole of the pressure gauge joint should not be less than 5mm. 7 Acceptance rules
7.1 Factory inspection
The pressure reducer shall be inspected one by one according to the requirements of Articles 5.2.a and 5.2.b of this standard, and can only be shipped after passing the inspection. If the inspection fails, the pressure reducer shall be judged as a defective product and cannot be shipped.
7.2 Type inspection
7.2.1 Inspection items
In the following cases, the pressure reducer shall be subjected to type inspection according to all technical requirements of this standard. .ta. Trial production of new products;
b. When changes in design, process or materials used affect the performance of the pressure reducer;c. Regular spot checks on pressure reducers in regular production
d. When the pressure reducer that has been stopped for a period of time is produced again. 7.2.2 Sampling and judgment rules
For the two situations of Article 7.2.1 a and b, four pressure reducers shall be sampled for type inspection, and each inspection item of each pressure reducer shall be qualified. For 7.2.For cases c and d of item 1, four pressure reducers shall be randomly selected from the products that have passed the export inspection for type inspection. If every inspection item of each pressure reducer is qualified, the batch of products shall be judged as qualified products, otherwise, the batch of products shall be judged as unqualified products. ERVED
JB7496-94
Appendix A
Flow conversion of test gas
(Supplement)
A1 When the test gas is inconsistent with the working gas, the measured flow rate is converted according to formula (A1): Qx=KQ
Where: Qx——flow rate of working gas, m2/h; Q——measured flow rate of test gas, m/h; - conversion coefficient, its value is shown in Table A1
Test gas
........
Acetylene gas
Carbon dioxide
Note: The conversion coefficient refers to the value under standard conditions, that is, the ambient temperature is 20℃ and the gas pressure is 0.1013MPa. Additional remarks:
This standard is proposed and managed by Xi'an Industrial Automation Instrumentation Research Institute. This standard is drafted by Xi'an Industrial Automation Instrumentation Research Institute. The main drafters of this standard: Zhang Zhanqi, Wang Jinyi, Hu Hexin, Liu Qingming, Wang Xuemeng, Kang Yu (A1)
People's Republic of China
Mechanical industry standard
Safety specification for gas cylinder pressure reducers for welding, cutting and forging processes
JB7496-94
JB 7496-94
Published by the Institute of Integrated Technology and Economics of Instruments and Meters, Ministry of Machinery Industry Printed by the Printing Service Department of Beijing Machinery Enterprises Association
Issued by the Institute of Integrated Technology and Economics of Instruments and Meters, Ministry of Machinery Industry★
First edition in September 1995
Print run: 250 copies
First printing in September 1995
Cost: RMB 7.00
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