Retrospective 176, the call of a 30-year-old player
Pressure-relief valves are valves that reduce import pressure to the required export pressure through regulatory agencies and maintain export pressure stability by relying on the medium's own energy. The following are key technical points in this area:
I. Core functions and rationale
Pressure regulation mechanisms
The dynamical opening of the valve is regulated by elements such as springs, membranes or pistons, which reduce the flow when the export pressure is higher than the fixed value, and increases the opening and achieves a dynamic balance when the pressure is lower than the fixed value. For example, the direct-activation pressure-relief valves drive directly through the membrane core and respond quickly but with a lower accuracy (±10%); the lead-relief valves use the main valve+conductor valve structure with a accuracy of up to >5% 。
Pyramid media adaptorium
For gas (air, gas, etc.) and liquid (water, steam, etc.) media. Gas-reducing valves are required to maintain the stability of the flaming air ratio to prevent damage to the equipment; liquid pressure-reducing valves (e. G., piped water-reducing valves) usually use full copper valves and nbr seals with a temperature tolerance range of 1-120°c。
Ii. Main types and structures
Disaggregated by structure
Pyramids: use membranes to detect changes in pressure and apply to low and medium pressure scenarios。
Pyramid piston: control the main valve piston through a conductor valve and treat large-flow high pressure media (e. G. Steam) piping。
Pyramid tubals: strong in balancing pressure but low sensitivity。
Classification by function
Pyrobaric depressure valves: export pressure fixed, e. G., laboratory gas supply system piping。
Pyrobaric decompressure valves: keep import/export differential constant for hydraulic systems piping。
Pyramid combination pressure-reducing valves: integrated conductors and main valves, with self-control under complex conditions。
Iii. Applications and standards
Industry
Reactive pressure control is used in petrochemicals, and the electricity industry regulates the boiler for water pressure; liquefied gas stations are required to meet gb/t 50493 safety standards and be equipped with an emergency cut valve。
Civil sphere
Household water pressure-relief valves prevent over-pressure damage to pipes and require horizontal installation and filtration。
Technical specifications
gb/t 12244-2006: determines the material, pressure-temperature grade and test requirements for industrial pressure relief valves。
Pyramid safety valves are activated: pressure monitoring devices are required to avoid back pressure abnormalities when combined with blast fragments。
Iv. Selected and maintenance elements
Select parameters
The range of voltage (e. G. 0. 1 - 5. 5 mpa), the characteristics of the medium and flow demand need to be considered. For example, the decompressive valve is applied to the construction pipeline and the export pressure is freely adjusted。
Installation requirements
Directly installed in horizontal pipelines with valve arrows consistent with the flow; the end of the gas pressure reduction valve requires a safe excretion valve。
Recommendation for maintenance
Seals are periodically checked for wear and tear, and conductor valve components need to be cleaned to prevent jamming。
