Richard Rumancik
11-20-2006, 5:36 PM
I need some suggestions in setting up the control for a small compressor. I want to use this compressor for airbrushing. I have a diaphragm type compressor to which I have attached a pressure regulator. There is a fixed relief valve on the compressor so that if the outlet is blocked then the relief valve releases the air. This relief valve is very noisy, however, and really meant to protect the compressor. I tried to add an adjustable relief valve on the output (before the regulator) so it would expel air when the outlet was closed, but this was unsuccessful as well as it was also very noisy and caused resonance and howling within the relief valve.
I did a bit of research and found some commercial airbrush compressors have a switch that shuts off the compressor when you close the trigger (output blocked.) It turns back on when you depress trigger (demand air.)
This seemed like a good idea as it stops the compressor from running instead of just wasting air through the relief valve. I tried wiring a switch in the circuit that had a cut-in of 20 psi and cut-out of 40 psi. (There is some adjustment available.) However, this does not work either. It will cut-out fine at 40 psi but tries to re-start at 20 psi when there is still pressure in the line. The compressor can't start under 20 psi backpressure - it just hums. In fact, it won't start unless I get the output to fall below a few psi. A normal switch doesn't go so low (e.g. cut-in of 1 psi).
So what am I missing here? How do they do it on the commercial airbrush compressors?
I did a bit of research and found some commercial airbrush compressors have a switch that shuts off the compressor when you close the trigger (output blocked.) It turns back on when you depress trigger (demand air.)
This seemed like a good idea as it stops the compressor from running instead of just wasting air through the relief valve. I tried wiring a switch in the circuit that had a cut-in of 20 psi and cut-out of 40 psi. (There is some adjustment available.) However, this does not work either. It will cut-out fine at 40 psi but tries to re-start at 20 psi when there is still pressure in the line. The compressor can't start under 20 psi backpressure - it just hums. In fact, it won't start unless I get the output to fall below a few psi. A normal switch doesn't go so low (e.g. cut-in of 1 psi).
So what am I missing here? How do they do it on the commercial airbrush compressors?