overpressure protection device - Safety reflux valve (return valve; Reverse flow valve)
The primary function of a safety valve is therefore to protect life and property.
Compressed springs to act as safety devices on pressurized vessels. The principle type of device used to prevent overpressure in plant is the safety or safety relief valve. The safety valve operates by releasing a volume of fluid from within the plant when a predetermined maximum pressure is reached, thereby reducing the excess pressure in a safe manner. As the safety valve may be the only remaining device to prevent catastrophic failure under overpressure conditions, it is important that any such device is capable of operating at all times and under all possible conditions.
Safety valves should be installed wherever the maximum allowable working pressure (MAWP) of a system or pressure-containing vessel is likely to be exceeded. In steam systems, safety valves are typically used for boiler overpressure protection and other applications such as downstream of pressure reducing controls. Although their primary role is for safety, safety valves are also used in process operations to prevent product damage due to excess pressure. Pressure excess can be generated in a number of different situations, including:
model A41H safety valve Usage
Reflux valves install at the liquid reflux pipe of LPG tank pump outlet. When the front pump pressure greater than rated value, safety reflux valve reduce pressure & back flow.
Structure
Safety reflux valve include flange parallel type (picture 4) and right-angle type (picture 2). Disc sealing material is PTFE (picture 5), good sealability. Valve open and close function is realized by the inlet and outlet different pressure.
safety relief valves Working principle
When inlet pressure is greater than outlet pressure of 0.5MPa, spring is compressed, and valve open automatically. When inlet pressure is less than outlet pressure of 0.5MPa, the valve get closed automatically by spring moving.
The terms 'safety valve' and 'safety relief valve' are generic terms to describe many varieties of pressure relief devices that are designed to prevent excessive internal fluid pressure build-up.
Pressure relief valve - A spring-loaded pressure relief valve which is designed to open to relieve excess pressure and to reclose and prevent the further flow of fluid after normal conditions have been restored.
This is a general term, which includes safety valves, relief valves and safety relief valves.
Safety valve - A pressure relief valve actuated by inlet static pressure and characterised by rapid opening or pop action.
Safety valves are primarily used with compressible gases and in particular for steam and air services. However, they can also be used for process type applications where they may be needed to protect the plant or to prevent spoilage of the product being processed.
Relief valve - A pressure relief device actuated by inlet static pressure having a gradual lift generally proportional to the increase in pressure over opening pressure.
Relief valves are commonly used in liquid systems, especially for lower capacities and thermal expansion duty. They can also be used on pumped systems as pressure overspill devices.
Safety relief valve - A pressure relief valve characterised by rapid opening or pop action, or by opening in proportion to the increase in pressure over the opening pressure, depending on the application, and which may be used either for liquid or compressible fluid.
l Working pressure's confirmation
| PN |
Set pressure rate (MPa) |
| (MPa) |
| 1.6 |
0.06~0.1 |
0.1~0.16 |
0.16~0.25 |
0.25~0.4 |
0.4~0.6 |
0.6~0.8 |
0.8~1.0 |
1.0~1.3 |
1.3~1.6 |
| 2.5 |
1.3~1.6 |
1.6~2.0 |
2.0~2.5 |
|
|
|
|
|
|
| 4 |
1.3~1.6 |
1.6~2.0 |
2.0~2.5 |
2.5~3.2 |
3.2~4.0 |
|
|
|
|
| 6.4 |
2.5~3.2 |
3.2~4.0 |
4.0~5.0 |
5.0~6.4 |
|
|
|
|
|
| 10 |
4.0~5.0 |
5.0~6.4 |
6.4~8.0 |
8.0~10.0 |
|
|
|
|
|
| 16 |
10~13 |
13~16 |
|
|
|
|
|
|
|
| 32 |
16~19 |
19~22 |
22~25 |
25~29 |
29~32 |
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