Low temperature valve and ordinary normal temperature valve difference and selection

        Low temperature valve as the name implies, that is, to be able to work in cryogenic low temperature working conditions of the valve, the demarcation of its working temperature, usually the working temperature below -40℃ valve is called low temperature valve, mainly used for gas liquefaction, separation, transportation and storage equipment, the use of temperature up to -270℃ below, There are gate valve, globe valve, check valve, ball valve, butterfly valve and throttle valve type.

        USES more and more widely in recent years, cryogenic valve, oil chemical industry, air separation, gas industry one of the indispensable important equipment, such as the working medium temperature is low, not only and most or toxic or flammable and explosive, and permeability is strong, thus determines the material and the design of valve and other special requirements. It is not only required to work properly at the set temperature, but also to ensure the working performance at room temperature.

        Low temperature valve compared with normal temperature valve, low temperature valve packing parts are increased, and the use of extended stem. Its purpose is to reduce the external heat into the device; Ensure that the temperature of the packing box is above 0℃, so that the packing can work normally; Prevent frosting or freezing of the stem and the upper part of the cover of the stuffing box due to over-cooling of the stuffing box.

        The design of the long neck valve cover is mainly the design of the neck length L, L refers to the distance from the bottom of the packing box to the upper surface of the sealing seat, and it is related to the thermal conductivity of the material, thermal conductivity area and surface heat dissipation coefficient, heat dissipation area and other factors, the calculation is more complicated, generally obtained by experimental method. Ferritic stainless steel can be used when the temperature is higher than -100℃, austenitic stainless steel can be used when the temperature is lower than -100℃, copper alloy or aluminum alloy can be used for low-pressure and small-caliber valves, the valve body should be able to fully withstand temperature changes caused by the expansion and contraction, and the structure of the seat part will not produce permanent deformation due to temperature changes.

        Source: Zhejiang Pump and Valve Industry Association