Controlling low air pressure

[mike_landeros]

I am looking for a device to control low air pressure, open at 2.0 psi, close at 3.5 psi. Any such device?

[Kelly_Bramble]

Pressure Switch/Sensor - Look at well pump type pressure switch companies and inquire about your on/off pressure range.

[Hudson]

You might use two valves in series. The first would open a 2psi and the second close at 3.5 psi. You could also combine an electrical with a mechanical valve to handle separate conditions.