Some standard content:
Mechanical Industry Standard of the People's Republic of China
Dry-type flashback fuse
1 Subject content and scope of application
JB/T 7437---94
This standard specifies the basic structure, technical requirements, test methods, acceptance rules, marking, packaging, transportation and storage of dry-type flashback fuses for welding and cutting equipment.
This standard applies to dry-type flashback fuses for acetylene gas and other flammable gases. Cited standards
GB1220 Stainless steel bars
GB 3863
GB3864
GB5107bZxz.net
GB5232
Industrial gaseous oxygen
Industrial gaseous fluorine
Hose joints for welding and cutting
Processing yellow steel Chemical composition and product shape
Dissolved acetylene
GB 6819
Basic structure and terminology
3.1 Basic structure
Dry-type flashback fuses are mainly composed of a one-way valve, a flame arrester, a housing and other components. The basic structure is shown in Figure 1. 3.2 Terminology
3.2.1 One-way valve
A valve that only allows gas to flow in one direction. 3.2.2 Flame arrester
A device that uses micropores to dissipate heat and extinguish flames. For example, microporous sintered powder metal tube. Approved by the Ministry of Machinery Industry of the People's Republic of China on September 6, 1994 580
Implementation on July 1, 1995
4 Basic parameters
JB/F 7437-94
4.1 The maximum working pressure of acetylene tempering fuse is 0.15MPa. 4.2 The threads of the inlet and outlet ends of the tempering fuse shall comply with the requirements of GB5107. 4.3 The working environment temperature is -20～60℃. 5 Technical requirements
5.1 Materials
5.1.1 Metal materials
One-way
Flame extinguisher
5.1.1.1 The copper content (mass percentage) of the alloy used for parts in contact with acetylene must be less than 70%, and its chemical composition shall comply with the provisions of GB5232 on lead brass.
5.1.1.2 The chemical composition and mechanical properties of stainless steel materials shall comply with the relevant provisions of GB1220. 5.1.2 Non-metallic materials
The materials used to manufacture non-metallic parts of flashback fuses must be materials with sufficient physical and chemical stability to acetylene gas, propane, oxygen and acetone.
No grease or oil is allowed in the parts that come into contact with oxygen. 5.2 Performance
5.2.1 Anti-flashback performance
When the pressure of the fuel gas-oxygen mixture is 0.15MPa, five consecutive flashback tests shall ensure that the fire is stopped, and the time interval between each test shall not exceed 405, but not less than 20s.
5.2.2 Anti-flashback performance durability
When the pressure of the fuel gas-oxygen mixture is 0.15MPa, 1000 consecutive tests shall ensure that the fire is stopped, and the time interval between each test shall not exceed 40s+, but not less than 20s.
5.2.3 Gas flow and pressure loss
JB/T 7437-94
Take the average value of the flow measured by five samples. The dispersion of the measured values of the flow of the five samples should not deviate from ±10%. The nesting is shown by a diagram (see Figure 2). The pressure drop force should not exceed 15% of the inlet pressure 1. Figure 2
5.2.4 The flashback fuse shall not leak at any part under a pressure of 0.25MPa. Gas flow, m*/h
5.2.5 The shell of the flashback fuse shall be able to withstand a 6MPa hydraulic pressure without permanent deformation and leakage. 5.2.6 The closing pressure p of the flashback fuse check valve is less than or equal to 0.02MPac6 Test method
6.1 Anti-flashback performance test
The sample is installed on the test device, and its test system is shown in Figure 3. Open valves A, B, C, and D, purge the system with nitrogen first, and then fill it with oxygen-acetylene mixed gas with a pressure of 0.15MPa (the mixing ratio is by volume, acetylene is 32%~38%). When the inlet pressure is 0.15MPa, close B and C, start the ignition device, and observe whether there is a flame passing through the flame detector (the inner hole diameter of the tempering tube is 10mm). 6.2 Anti-flashback performance durability test
The test method shall be carried out in accordance with the provisions of Article 6.1.
6.3 Gas flow and pressure loss test
The sample is installed on the test device, and its test device system is shown in Figure 4. Using oil-free air or nitrogen (the volume conversion ratio of air to acetylene is 1.049:1, and the volume conversion ratio of nitrogen to acetylene is 1.0311), at different inlet pressures (until the maximum allowable working pressure pm), when it flows freely to the atmosphere according to Figure 4, measure the gas flow at different intermediate pressures. Inlet pressure P
Flame detector
Outlet pressure P#
1 Ignition element
5000rutm
Inlet pressure gauge
JB/T 7437-94
Outlet pressure gauge
Repeat the same test with inlet pressures equivalent to 0.25rutmax, 0.5rutmx, and 0.75rutm, and measure the flow rate at different pressures △b. 6.4 Air tightness test
Install the sample on the test device, fill the sample with grease-free dry gas from the outlet, pressurize it to 0.25MPa, immerse the sample in water, and keep it for 30s. No leakage is allowed in any part, and repeat the air tightness test after the anti-tempering test. 6.5 Shell strength test
Install the shell of the tempering fuse on the hydraulic test device, pressurize it to 6MPa, and maintain it for 5min. No permanent deformation or leakage is allowed. 6.6 One-way test
Install the sample on the test device. The test system is shown in Figure 5. Open valves G, F, and A, and fill it with oil-free air or nitrogen. When the pressure gauge shows 0.15MPa, close valve G and gradually open valve C. After 60s, the value indicated by U-type pressure gauge I is the closing pressure value. Then close valve C, open valves D and E, and fill it with oil-free air or nitrogen from the reverse direction of the sample to 5 times the closing valve pressure value. Continue for 60s. The value indicated by U-type pressure gauge 1 should remain unchanged at the closing pressure value.
6.7 Accuracy of test instruments
The accuracy of pressure gauge shall not be lower than Class 1.0;
The accuracy of flow meter shall not be lower than Class 2.5;
The accuracy of U-type pressure gauge shall not be lower than Class 2.5. U-type pressure gauge 1
7 Inspection rules
7.1 Factory inspection
7.1.1 Inspection one by one
Normal air flow
U-type pressure gauge I
Pressure gauge
7.1.1.1 All the flashback fuses shipped out of the factory shall be inspected one by one according to the items specified in Table 1. If all three inspection items are passed, the product is judged to be qualified; if any of the inspection items are not passed, the product is judged to be unqualified. 583
Inspection items
Anti-tempering performance test
Anti-tempering durability test
Flow-pressure loss test
Air tightness test
Shell strength test
One-way flow test
Repeated air tightness test
7.1.2 Batch inspection
7.1.2.1 Batch sampling and grouping
JB/T 7437—94
Test method
Inspect one by one
Batch inspection (type test)
First group
Second group
Third group
Judgment basis
For products with the same design, same process and same material produced continuously, 5000 pieces shall be considered as one batch. The samples for batch inspection are taken from the qualified products inspected one by one. Ten samples are taken from each batch of products and divided into three groups for inspection. The first group has five, the second group has three, and the third group has two. 7.1.2.2 All tempering fuses leaving the factory shall be batch inspected according to the items specified in Table 1. If all the inspection items are qualified, the batch of products shall be judged as qualified products. When the tempering resistance durability test fails, the batch of products shall be judged as unqualified products. When the tempering resistance durability test passes, if any of the other inspection items fails, double sampling is allowed. If there are still unqualified items, the batch of products shall be judged as unqualified products.
7.2 Type test
7.2.1 Type inspection shall be carried out when the product has one of the following conditions a.
When new product trial production and identification:
When the design, process or materials used of the product are changed; when production is resumed after suspension for more than six months: when the national quality supervision agency puts forward the requirement for type inspection. The number and grouping of samples for type inspection shall be in accordance with 7.1.2.1. The type inspection items shall be in accordance with the provisions of Table 1, and the inspection results shall be determined in accordance with the provisions of Article 7.1.2.2. 8 Marking, packaging, transportation, storage
Each flashback fuse shall be marked with the following content: 8.
Manufacturer name or registered trademark;
Product model $
Gas flow direction symbol;
Quality inspection pass mark and seal,
Manufacturing date or production batch number.
8.2 Packaging
8.2.1 Each flashback fuse shall be accompanied by a product certificate and product instructions when leaving the factory. 8.2.2
The threads of the inlet and outlet of the flashback fuse shall be kept clear and oil seals are not allowed. 8.2.3 The packaging box shall indicate the product model, product name, quantity, weight, volume and manufacturer name. 8.3. Transportation
The flashback fuse should be transported with care and moisture-proof. 8.4 Storage
JB/T7437
The flashback fuse should be stored in a dry, ventilated room that does not contain flammable, explosive and grease-free items. Additional remarks:
This standard was proposed and coordinated by Harbin Welding Research Institute of the Ministry of Machinery Industry. This standard was drafted by Harbin Welding Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Ri Zhenjie and Wang Run. 585
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