Safety valve selection and installation considerations: the operating temperature of the safety valve to determine the scope of the use of safety valve, the operating pressure to determine the safety valve nominal pressure. Determined by the calculation of the safety valve of the value of the spring or lever to determine the range of pressure, and then use the media to determine the safety valve of the material and structural type, and then according to the safety valve leakage volume to calculate the safety valve throat diameter. The following is the general rules of the selection of safety valve.
1, hot water boiler is generally not closed with a wrench micro open type safety valve.
2, steam boiler or steam pipe is generally closed with a wrench open with a safety valve or a safety relief valve.
3, water and other liquids can not be compressed in general with a closed micro open type safety valve. Such as high pressure feed water heater, heat exchanger, etc..
4, high pressure water supply generally closed with the full swing type safety valve. Such as gas storage tanks, gas pipelines, etc..
5, gas and other compressible medium generally closed with the full swing type safety valve.
6, E class steam boiler in general with static heavy type safety valve. Pulse type safety valve for large displacement and high pressure system.
7, large diameter. Such as temperature and pressure reduction devices, power station boilers, etc..
8, train transporting liquefied gas tankers, tank trucks, tanks and other general use built-in safety valve. Need to cooperate with the use of breathing valve.
9, tank top general with hydraulic safety valve.
10, underground drainage or natural gas pipeline in general with the pilot type safety valve.
11, liquefied petroleum gas station can pump the liquid return pipe on the general safe return valve.
12, negative pressure or operation process may produce negative pressure system generally use the vacuum negative pressure safety valve.
13, back pressure to shake the larger and toxic flammable container or piping systems generally use Bellows Safety valve.
14, the system is generally used to select the low freezing point of the system insulation jacket type safety valve.
Safety valve installation precautions
Safety valve is an important safety accessories for special equipment, its installation also has the corresponding requirements, the following list of some common items:
1, rated evaporation is greater than 0.5t/h of the boiler, at least two safety valves installed: rated evaporation is less than or equal to 0.5t/h of the boiler, at least a safety valve installed. Can economizer exit steam superheater outlet must be installed safety valve.
2, the safety valve should be installed vertically in the pot, the highest position of the box. Between the safety valve and the boiler drum or header, the outlet pipe and the valve of the steam can not be installed.
3, the lever type safety valve to prevent the hammer guide their own mobile devices and to limit leverage deviant, spring-loaded safety valve should improve handle and prevent casual twist screw adjustment device.
4, for the rated steam pressure is less than or equal to 3.82MPa of the boiler, safety valve throat diameter should not be less than 25mm: for the rated steam pressure is greater than 3.82MPa of the boiler, the safety valve throat diameter should not be less than 20mm.
5, the safety valve and the boiler connection pipe, the cross-sectional area should not be less than the safety valve inlet section. If several safety valves installed in a common root with the drum directly connected to the short, 1.25 times short tube channel cross-sectional area should not step on all exhaust valve area.
6, the safety valve should normally be installed in exhaust pipe, exhaust pipe should be through a safe place, and with sufficient cross-sectional area to ensure that the exhaust flow. Exhaust valve at the bottom should have received security posturing location of drainage pipe, the exhaust pipe and drain pipe installed on the valve are not allowed.