Pneumatic valve selection inquiry order matters needing attention in low temperature

low temperature pneumatic valve means can be used under low temperature conditions of the pneumatic valve, the working temperature is below - usually The pneumatic valve called cryogenic pneumatic valve ℃. Cryogenic pneumatic valve is petroleum chemical industry, air separation, gas and other industrial one of indispensable important equipment, its quality fit and unfit quality determines whether security, economy and continuous production. With the development of modern science and technology, cryogenic pneumatic valve USES more and more wide, demand is also increasing.
for temperature above - ℃, generally do not use long neck structure, to temperature below - ℃ of the pneumatic ball valve, neck length T according to escape fast design and calculation of the pneumatic valves. Cryogenic pneumatic ball valve is mainly used for output medium a cryogenic liquid such as ethylene, liquid oxygen, liquid hydrogen, liquefied natural gas, liquefied petroleum products, etc. , not only the flammable and explosive, and in to gasification temperature, gasification, the volume expansion of hundreds of times.
liquefied natural gas (LNG) pneumatic valve material is very important, the material is unqualified, will cause the housing and the sealing surface of leakage or leakage; Parts of comprehensive mechanical properties, strength and stiffness can't satisfy the use requirement and even rupture. Liquefied natural gas (LNG) medium leak caused an explosion. Therefore, in the development, design, development of liquefied natural gas (LNG) in the process of pneumatic valves, material is the primary key problem. Pneumatic valve, pneumatic valve cover adopt: LCB ( - ℃、LC( - ℃,CF ( ） ( - ℃.
low temperature pneumatic valve pneumatic valve cover structure requires a long neck, the day is to reduce the heat from the incoming device; Ensure that the temperature of the stuffing box parts in ℃ above, make the packing can work normally; Prevent make by stuffing box part too cold in the stuffing box parts of the upper part of the pneumatic valve stem and valve cover parts frost or freeze.
long neck pneumatic valve cover design is mainly the design of the neck length L, L refers to the stuffing box at the bottom of the distance from the surface to the seal seat, it and the coefficient of thermal conductivity, thermal conductivity material area and the surface coefficient of heat transfer, heat dissipation area of factors, such as computation is trival, generally obtained by experimental method.
low temperature pneumatic valve working conditions are harsh, most of the working medium for inflammable, explosive, porous material, the lowest working temperature can reach - ℃, the highest working pressure of MPa. Therefore, low temperature air valve design, fabrication, inspection has the very big difference compared with the general pneumatic valves.
a lot of people, just put the pneumatic valve material is low temperature steel is believed to be low temperature pneumatic valve directly, actually otherwise, it's only a cryogenic pneumatic valve of semi-finished products, because it didn't after cryogenic treatment at low temperature, and low-temperature cryogenic treatment is the nods eyeball pen of cryogenic pneumatic valve, pneumatic valve is the key in cryogenic treatment at low temperature, which ensures that all parameters of the pneumatic valve is achieved at low temperature, especially the expansion coefficient, will not lead to appear in using all kinds of pneumatic valve is stuck. Sometimes under considering the price problem, also want to consider the quality of the pneumatic valve. Pneumatic valve belongs to special pneumatic valve in low temperature.
but now most of the low temperature domestic pneumatic valves are not after cryogenic treatment at low temperature, the first cost would be expensive, I can give you a rough here, if you add set of cryogenic equipment cost is high, the cryogenic equipment is expensive, and cryogenic in addition to the necessary material and liquid nitrogen is a bad storage medium, and processing in a pneumatic valve consume a lot of liquid nitrogen, and the price of liquid nitrogen is not cheap. On the low-temperature pneumatic valves produced by the special low temperature treatment, rough machining of parts in the cooling medium for hours ( - Hours) To release the stress, to ensure material low temperature performance, ensure finishing size, in case of pneumatic valves in the condition of low temperature and deformation caused by temperature change caused by the leakage of low temperature pneumatic valves. The name of the low temperature medium; The temperature of the medium at low temperature; You need to customize their so low temperature long neck length, pneumatic valve by pneumatic valve standard does not provide will; The material of low temperature air valve ( Can customize according to customer's requirement) ； The pressure of cryogenic pneumatic valves; Pneumatic valve seal (low temperature Soft seal and hard seal) ； Connection ( Flange connection or welding) ； Drive way, Manual, pneumatic, electric) 。