2、 Design requirements for valve body and valve stem bushing: 1) Structural shape of low-temperature valve shell. Whether the material selection is correct or not is of great significance to the normal and reliable operation of the valve. Compared with the stop valve and gate valve, the structural characteristics of the butterfly valve not only avoid the deformation caused by the cold shrinkage and temperature difference stress at low temperature due to irregular shape, uneven shell wall thickness, but also the small volume of the butterfly valve and the basically symmetrical shape of the valve body, so the heat capacity is small; Pre cooling consumption is also small; Regular shape is convenient for cold insulation measures of valves. For example, the newly developed DD363H butterfly valve is designed and manufactured in full accordance with the particularity of the cryogenic valve to ensure the reliable use of the valve at low temperatures. For example, the shell material is 1Cr18Ni9Ti austenitic stainless steel with cubic lattice.
2) Selection of valve rod bushing: according to the user's feedback, some low-temperature valves of special oxygen valves are in operation, and the rotating parts of the valves are stuck and occluded from time to time. The main reasons are: the selection of matching materials is unreasonable, the reserved cold clearance is too small, and the processing accuracy and other reasons. When developing cryogenic valves, a series of measures were taken to prevent the above phenomena. For example, we have selected SF-1 composite bearings with small friction coefficient and self-lubricating performance for the upper and lower bushings of the valve stem, which can meet some special needs of cryogenic valves. The metal sealed butterfly valve has the characteristics that some ordinary valves do not have. Especially, it has small flow resistance, reliable sealing, rapid opening and closing, long service life, etc.

The first thing to note is that under normal circumstances, the electric butterfly valve will be slightly hot, especially when the switch is frequent, so it is normal to slightly hot. If it feels higher than the normal temperature, and the valve is still very hot after several minutes of stagnation, then there is a problem and it needs to be solved as soon as possible.