Air Compressor Pressure Switch

We provide you with valuable information about air compressor pressure switch.

Air Compressor Pressure Switch

The reason for this article about pressure switch is that most people underestimate the value of a proper working switch until they get burnt. In order to avoid air compressor damage, switch must be in perfect working shape.

What does this switch actually do? Air compressor pressure switch basically regulates the power that comes to your compressor in order to prevent permanent damage. Tank pressure has a preset limit which is about 125 psi for many models that are single stage. You do not really need that much pressure in normal work but when you get to the limit, pressure switch is there to stop the pressure from harming your compressor by turning off the motor, which lowers pressure. Note that pressure switch does not regulate the pressure, that job is for air compressor regulator to do.

When pressure goes below normal work pressure, the switch will turn the motor on again. Some pressure switches come with a valve (called unloader valve) that will reduce tank pressure when you turn off your compressor.

How it actually works?

Pressure switch regulates the power, turning motor on and off. Almost always power wires that go to your compressor are being controlled by pressure switch. Since the power is usually in form of 120 VAC and 240 VAC single phase electrical current, it uses either one neutral and one power wire (in case of 120VAC) or two power wires (240VAC). In both cases, there will be either a green insulated wire or bare copper wire as part of the safety circuit. Installing a pressure switch is not really complicated and in many cases it can be done by yourself, of course depending on the compressor you own.

Lets talk a bit about the settings on the pressure switch.

On most pressure switches there are two main settings: Differential pressure and Maximum pressure.
You start off with setting maximum pressure first. Lets say we set it at 7 bar. Then we proceed to set differential pressure, lets say 1 bar. With those settings the compressor will start at 6 bar (maximum pressure minus differential pressure, in this case 7-1=6) and it will stop at maximum pressure. Take care to set the pressure switch when there is actual pressure on it, or you risk damage.

Purchasing an air compressor switch.

Lets say you found out in time that you need to replace your switch or it died unexpectedly on you, what should you be looking for in new one?

Important factors to consider are :

1.) Pressure band. Is it enough for your compressor? example 0-3 bar or you need 3-10bar.
2.) Minimum differential pressure.
3.) Type of fluid your compressor uses, is it liquid or gas?
4.) What is the operating temperature for the switch itself?
5.) What kind of sensor mechanism pressure switch uses?
6.) Does it have disconnect metal lever for manually shutting down the compressor?

Some other things that are also good to look for are quality of life improvements such as corrosion proof covers, pulsation dampeners and no drift pressure setting.

Also, you should always use a pressure switch that is actually rated for your motor and your air system. If wiring by yourself, follow all local electrical codes.
I would also advise you against tampering with the factory settings on the switch itself. If you don’t REALLY know what you are doing you can cause overpressurization which will cause damage to your air compressor.