The assembled pneumatic ball valve cannot be sealed. In order to ensure that there is no leakage during the assembly of metal sealed pneumatic ball valve, the plating layer shall be 0.03ram. After electroplating, the ball shall be reground to remove excess metal and ensure the roundness of the ball. The roundness and roughness of the sphere processed by this method meet the requirements of the drawing. Comply with API inspection standards. If the grinding device reformed from the power head is matched with the spherical lathe to form a combined turning, grinding and grinding machine tool, it is completely possible to realize the gas sealing of the metal sealed pneumatic ball valve. Generally, three jaw chuck or four jaw chuck clamping method is used to process the 90 degree sealing surface of the valve seat. The workpiece processed by this method has more turning at the jaw, which makes the workpiece out of round at many points. Thus, process the valve seat 90. The method of pressing shall be adopted for the conical surface. When finishing the final turning, loosen the pressing plate and press it gently again. After the valve seat is machined, the valve seat shall be lapped by the method of ball and valve seat lapping to improve the roughness (R4o. 8Fro) and the roundness of 9O cone surface, so that the sealing between the ball and the valve seat will not leak. When fixing the seal, the pre compression is 0.25d (d is the diameter of the rubber strip of the O-ring). For sliding seal, the pre compression shrinkage is 0.15d. In the fixed ball pneumatic ball valve, the preload of the O-ring shall be calculated by connecting the sliding seal 0.15d. However, at present, the O-ring pre compression of the fixed ball pneumatic ball valve is too large. Pneumatic ball valve is a kind of valve with higher processing and assembly requirements, and the processing precision of fixed pneumatic ball valve is required to be higher. Only by constantly summarizing the experience of the production process and exploring more scientific and innovative methods can we produce high-quality, high-level fixed pneumatic ball valves.

The liquid flow rate can be selected in the range of 1~10m/s at the full flow rate of EMF, and the range is relatively wide. In principle, the upper limit flow rate is unlimited, but it is generally recommended not to exceed 5m/s. Unless the lining material can withstand liquid flow erosion, it rarely exceeds 7m/s in practical application, and it is even more rare if it exceeds 10m/s. The lower limit of flow rate of full flow is generally 1m/s, and some models of instruments are 0.5m/s. For some pipeline systems with low flow or low flow rate at the initial stage of operation of new projects, from the perspective of measurement accuracy, the instrument diameter should be smaller than the pipe diameter and connected with a reducer.