DIY – Air Pressure Switch

home-made-pressure-switch

There is no secret that many Airbrushists love to use DIY stuff as it comes much cheaper and they can spend more money for a good airbrush gun.

Home-made compressor build of old refrigerator compressor with an old fire extinguisher tank or even with coke bottle tank and car fuel filters in it isn’t unusual anymore. Even manometer isn’t a problem to get. The biggest problem is to find an air pressure switch or set it up so it will work properly. I have found out a temporary solution which can be made in few minutes untill you get the real one.

Double-Action airbrush or even beginners airbrushes with siphon feed must have the pressure switch. If you don’t have any pressure switch at the moment, you can get into situation when the air hose wrests off the airbrush and whistling flies all over your workplace. The problem, as you know, is high pressure. The compressor just won’t stop pumping the air into receiver untill you switch it off. I received a recommendation once to use a bottle of champagne as receiver but then what if the pressure will be too high? The consequences after explosion of glass bottle could be really bad. In fact, did you know that glass can’t be seen under X-Ray? You need pressure switch even if it’s a temporary home-made one.

Once, when I was fitting the air hose onto airbrush I noticed that it is easier to do when compressor is on. The rubber hose gets wider in diameter. To make a switch that will break the electric circuit will take a bit more time. What if I just make a breaker that won’t cut off the electricity but can break an air circuit which will result into a huge reduction of air pressure?

EUREKA! I can make it in five minutes. How? Can you afford to make a hole in your air hose that goes to airbrush? If yes, you are good to go. I think that some of you got the idea already. See, if you make a hole (0.5mm) in the hose you will notice that pressure drops down. The thing is just to make the hole to open up at certain pressure. The air hose is made of silicone, mostly. We need just a piece of dry rubber hose which we can slide on silicone hose and cover the hole. When the pressure gets high the dry rubber stretches more than silicon and opens the hole. By moving the dry rubber hose, as it is shown below, we can set the pressure limits.

First experiments had some cons. The breaker went on with ear-piercing noise. Tooth-pick solved the problem and the noise transformed into harmless hiss.

Conclusion

Construction is very easy and clear from the picture above. The only thing to consider is how long will dry rubber last? I don’t know how elasticity of dry rubber changes over time (probably not that much).

At the end I included some numbers from my test:

  • The breaker starts at 33 – 36 psi
  • In Idle cycle (not working with airbrush), the pressure stabilized around 56psi
  • When working with airbrush the pressure stabilized at 28 – 30psi