As the advantages and disadvantages of pneumatic valve

as pneumatic valve opening and closing is plug piece of pneumatic valve, sealing surfaces appear flat or cone, pneumatic disc make linear movement along the centerline of the fluid. Pneumatic valve stem form of exercise, lifting lever ( Pneumatic valve rod and hand wheel lifting) And lift rotating lever ( The handwheel with pneumatic valve rod rotating lifting, nut is located in the pneumatic valve) 。 By pneumatic valve used throughout opened only close, not allowed to adjust and throttling.
by the pneumatic valve belong to mandatory sealed pneumatic valve, in pneumatic valve is closed, so must to pressure pneumatic disc, to force a sealing surface does not leak. When medium by pneumatic disc below 6 into the pneumatic valve, operating force to overcome the resistance force, is the pneumatic stem and packing of the friction force and the thrust produced by medium pressure, close the pneumatic valve force than the pneumatic valves open force is big, so the larger the diameter of the pneumatic valve stem, or pneumatic stem top bending failure happens. In recent years, from the seal of the pneumatic valve door, as the flow direction of medium of the pneumatic valve is replaced by air above the disc into the pneumatic valve cavity, in the medium pressure at this moment, close the pneumatic valve is small, the force and the great strength of pneumatic valve, pneumatic valve stem diameter can be reduced accordingly. At the same time, in the role of media, this kind of pneumatic valve is tight. Pneumatic valve in China 'three for' regulation, by the flow of the pneumatic valve shall be applied.
as the pneumatic valve opens, the opening of pneumatic disc height, for the nominal diameter % ~ %, traffic has reached maximum, said the pneumatic valve to full open position. So by the pneumatic valve fully open position, should be determined by pneumatic disc trip.
as of pneumatic valve has the following advantages:

simple structure, manufacture and maintenance more convenient.
working stroke is small, opening and closing time is short.
good sealing, sealing surface friction between the small, long service life.
as the shortcoming of pneumatic valve is as follows:

fluid resistance is big, opening and closing the required force is larger.
is not applicable to medium with larger particles, viscosity, easy to coking.
poor regulation performance.
as the types of pneumatic valve according to the location of the pneumatic valve stem threads with external thread type, internal thread type. According to the flow of medium, have straight-through type, straight and Angle. By the pneumatic valve points, the form of the seal packing seal by the pneumatic valve and pneumatic valve bellows seal globe.
as pneumatic valve installation and maintenance should be paid attention to the following:

the handwheel, handle the operation by the pneumatic valve can be installed in any position.
the handwheel, handle and wei mechanism, does not allow for lifting.
the flow of medium should be consistent with the direction arrow shown in pneumatic valve body.