In real life, the pneumatic on-off valve can be found in many applications. This article will discuss the 5 main types of pneumatic on-off valves, explaining their features.
A pneumatic valve is driven by the compressed air. It can control the flow of different liquid types, such as air, water, steam, corrosive medium, slurry, oil, liquid metal and even radioactive medium.
1. Ball valve: the ball valve is developed from the coak valve. Normally the all valve is suitable for open-close function, but the modern ball valve is capable of throttling and fluid control. The ball itself controls the on and off status.
It features in:
low fluid resistance, the resistance coefficiency is the same to the pipeline which has the same length.
total sealing can be realized even at high pressure or high temperature.
fast open and close feature.
better corrosive resistance due to total separation between the ball and the sealing surface of the valve seat when the valve is totally opened or totally closed.
simple structure, easy to maintain, replace and repair.
2. Butterfly valve: a butterfly valve opens and closes in a left-right way with a disc.
It features in:
small fluid resistance, fast opening and closing.
simple structure, small footprint and easy installation.
can be used for large size valve.
can be used to transport slurry.
poor sealing performance.
3. Gate valve: this valve has a valve plate which moves vertically along with channel axis.
It features in:
small fluid resistance, small flush and corrosion resistance from the medium to the sealing surface.
labor-saving.
flow direction of the medium is not restricted, pressure is not reduced.
simple structure, short size, good technology and wide application.
not wearing resistance.
4. Stop valve: its closing part moves along with the centre line of the valve seat. Once the stop valve is opened, the sealing surfaces of the valve seat and valve clack do not contact with each other. This characteristic makes stop valve an ideal device for cutting and regulating medium.
It features in:
better wearing resistance.
small footprint.
usually has one sealing surface only, meaning that the maintenance is easy.
large fluid resistance, easy pressure loss.
5. Membrane valve: there is a flexible membrane inside the valve body, the sealing is controlled by the upside and downside movement of the membrane.
It features in:
easy dismantle and maintenance.
the medium is clean because the mechanism is separated from the medium channel.
the material inside can be various, widely applicable to the different medium.
it can not be used in the high-temperature environment.
