①The rubber ring is produced at designated points to strengthen the quality control. Usually used for valves in the water supply industry, EPDM and nitrile rubber are used. Natural rubber is not used much. It is strictly forbidden to mix with reclaimed rubber;% The entire pressure plate of the sealing rubber ring on the board is changed to a short dovetail assembly connection. The domestic self-priming pump adjusts the pressure of each part of the pressure plate to balance the life of the sanitary butterfly valve, but this adjustment technique is also difficult to master;
②Some manufacturers have launched DB sanitary butterfly valve and flange sanitary butterfly valve. Their sealing rubber ring is embedded in the dovetail groove, and there is a certain amount of movement margin, which can adjust the extrusion condition of the rubber ring when the sanitary butterfly valve is closed;
③Some manufacturers introduced a kind of "fluoroplastic" sealing ring to replace rubber sealing ring, and a small vacuum pump improves the wear resistance and aging resistance of the sealing ring;
④Many manufacturers have introduced metal-sealed sanitary butterfly valves to replace rubber-sealed sanitary butterfly valves.
The metal-sealed sanitary butterfly valve generally adopts an eccentric structure, especially a three-dimensional eccentric structure, due to the less elasticity of the seal. The metal-sealed sanitary butterfly valve was originally used on high-pressure steam pipelines, and the price is relatively expensive. Its sealing surface is not easy to be damaged during operation, but its manufacturing accuracy is high, and it is difficult to repair once leakage.
1) The structural shape of the cryogenic control valve housing. The correct choice of materials is of great significance to the normal and reliable operation of the regulating valve. Compared with globe valves and gate valves, the structural features of sanitary butterfly valves not only avoid deformation caused by irregular shapes, uneven shell wall thickness, cold shrinkage at low temperatures, and temperature stress, but also due to the volume of sanitary butterfly valves. Small, the shape of the valve body is basically the same on the left and right, so the heat capacity is small; the pre-cooling consumption is also small; the shape is regular and it is convenient for the cooling measures of the regulating valve.
2) Selection of stem bushing: According to users' feedback, some low-temperature control valves are in operation, and the rotating parts of the control valve are sticky and seizure occurs from time to time. The main reason is: the unreasonable selection of matching materials, leaving a cold gap Too small, and processing accuracy and other reasons. When developing the cryogenic control valve, a series of measures were taken to prevent the above phenomenon. For example, we selected SF-1 type composite bearings with low friction coefficient and self-lubricating properties for the upper and lower bushings of the valve stem, which can be suitable for some special needs of low-temperature control valves.
In this way, our sanitary butterfly valve has been greatly improved and improved.