The flow of bellows globe pneumatic valve problem

　 . General when nominal size DN mm or less for the low into the higher, when nominal size DN acuity mm high to low, when the nominal size DN mm or higher at the same time, easy to open, all additional ventilation move within the valve or side outside vent valve structure.
　　
　　. Progress under the type of the pneumatic valve packing seal compression in an all-round way, and on down into the type of the pneumatic valve sealing surface compression, just for large diameter by the pneumatic valve, if in the out pipe for high pressure at the same time, under the pneumatic valve stem diameter must be thick, if fine, pneumatic stem top corner accident will happen. Aspirant type under the open torque, closed torque is small.
　　
　　. Special cause of high in low out

( ） Pneumatic valve pressure side of high pressure, need high in low out

( ） Bypass on two stop pneumatic valve series, the second by pneumatic valve should always put the

( ） The boiler exhaust vent as pneumatic valve

( ） Electromagnetic speed to snuff out valve

. At present abroad to large diameter pneumatic valves are used to make progress under the type, and is usually designed to be double pneumatic disc ( Balanced pneumatic disc) , designed to double pneumatic disc purpose has two:

. When the pneumatic valve is opened or closed to avoid too much pressure difference.
　　
　　. Considering the rigidity of the pneumatic valve, high in low out has a clear effect on pneumatic valve, usually large diameter by the pneumatic valve is not designed to be double pneumatic valve, pneumatic valve is difficult to pin the medium.