Solenoid Valve : Air and Inert Gases

Solenoid Valves for Air and other Inert Gases

What solenoid valve materials can I use.

Brass, Plastic or Aluminium 2/2, 3/2, 5/2 and 5/3 way Solenoid Valves can be used for Compressed Air for air line equipment and pneumatic tools including most other inert gases such as Argon, Helium, Nitrogen and (CO2) Carbon Dioxide at ambient temperatures. As these are inert, non-aggressive gases that will not corrode or attack the materials of construction of the solenoid valve. Attention needs to be given to function, pressure and operation to that the correct solenoid valve is chosen for the right application.

Solenoid Valve Temperature and Pressure Ratings.

An additional key point to ensure safe application also includes temperature. The application may well be at 20C ambient, but when releasing compressed gas the expansion of the gas will absorb heat much like the working principle of a refrigerator and thus the temperature will drop according to the pressure difference. Normally at standard pressures to 10 bar there is no real concern, but at the pressures increase valve compatibility is of extreme importance, which is why all solenoid valves have a pressure rating, not only a maximum pressure rating but also on occasion a minimum pressure rating.

Solenoid valve sizing is also important when controlling gases to achieve the required system flow but also sometimes to achieve the minimum pressure difference required to operate pressure assisted, servo assisted, floating diaphragm / piston solenoid valves.

Bearing in mind that gases are compressible, the flow rates calculation can sometimes feel like a minefield as flows are normally given in CV or KV based on water flow at 1 bar pressure difference. i.e. the volume of water expected to flow through a solenoid valve with an inlet pressure 1 bar higher than the outlet pressure. 

Solenoid Valves for Vacuum Applications.

Basically the principles are the same as standard general purpose solenoid valves except that they are designed to work with negative or zero pressure differential and are typically hung diaphragm or direct acting solenoid valves designed to open regardless of system pressure differences.

So, the more pressure difference you have the more flow you will achieve until you hit what we call the sonic barrier, where the flow has reached the speed of sound and regardless of pressure no more flow can be achieved. 

In summary when using compressed air and other inert gases basic general purpose Brass, Plastic or Anodised Aluminium solenoid valves are fine when chosen correctly to suit the application.

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