The Air compressor pressure switch is an important part of electric air compressors. It helps maintain a proper level of pressure inside a compressor by turning it on and off.
The pressure switch turns off the compressor when the pressure inside the air tank rises to a certain level and no more air is needed to be compressed. Similarly, the pressure switch turns the compressor on when the pressure level inside the tank drops to a certain level, and more air is required to be compressed.
One important thing to note is that the pressure switch is a part which is used quite often while your air compressor is operational and hence it wears down quite quickly as compared to other air compressor parts. You need to check it from time to time and in case it is damaged, you need to fix or replace it as soon as possible. The pressure switch is your best line of defense against any possible ruptures as it prevents the tank from getting over-pressurized.
How does a compressor pressure switch works
The air compressor pressure switch monitors the pressure of compressed air moving in and out from the air tank. It uses some kind of element, or a diaphragm in most cases, to help detect the pressure level. As the air pressure inside the tank increases, the diaphragm shape changes resulting in the disconnection of electricity/power to the air compressor motor. Which, in turn, shuts off the air compressor.
The pressure at which the shape of the diaphragm changes enough to stop the power flow to motor resulting in the motor shutdown is called cut-out pressure.
When the pressure inside the tank decreases and drops down to a certain level, the diaphragm gets back into its original shape making the circuit close. As a result, the power flows back to the motor and the motor starts again to compress more air.
Air compressor pressure switch adjustment
As you know, the pressure switch turns the air compressor on and off based on certain levels of air pressure inside the tank. These pressure levels are called cut-in and cut-out pressures.
The cut-in and cut-out pressures can vary depending on the compressor. In most cases, the default factory cut-in, cut-out pressures will work for most users.
The need of adjusting the pressure mostly arises when you replace the existing pressure switch with a new one.
Check out this article on air compressor pressure switch adjustment that can give you a detailed explanation of the topic and the different steps to adjust the pressure switch.
Caution: Setting the air compressor pressure switch cut-out pressure too high can be dangerous as it might result in a tank explosion.
Pressure Switch Types and Models
Different types and models of pressure switches are available in the market. The types can be broadly divided into two types
- Electromechanical pressure switch
- Solid State switch
The type of pressure switch can further be categorized based on the different pressure adjustments they offer. Check out the air compressor pressure adjustment article to understand the different adjustments.
Air Compressor Pressure Switch Wiring Diagram
Below is the Square D pressure switch wiring diagram. Connect your power lines at 1 and 3. The motor wires would connect to 2 and 4.
FAQ (Frequently Asked Question)
How do you know if the pressure switch is bad on an air compressor?
Your pressure switch can go bad quite often as it is among the most-used air compressor parts. You know that your pressure switch is bad if it shows any of the following signs
- the pressure switch leaks
- the air compressor doesn’t start, in which case pressure switch can be the reason.
- the compressor stops before reaching the cut-out pressure
- the compressor doesn’t start at the cut-in pressure
- the compressor doesn’t stop at the cut-out pressure
What happens if pressure switch goes bad?
In case of a bad pressure switch, your air compressor could not start at all. In the worst case, the compressor could not stop and keeps compressing more air, building more pressure inside the tank despite exceeding the cut-out pressure. This situation is alarming and can even blow your air compressor motor or the tank, which can be deadly.
What does a pressure switch do on an air compressor?
A pressure switch maintains the air pressure inside the tank of an air compressor by setting the cut-in and cut-out pressures. You can use the different adjustment screws available on your pressure switch to adjust the cut-in and cut-out pressures.
What is the Purpose of Air Compressor Pressure Switch?
As discussed throughout the article, the purpose of the pressure switch is to start and stop the air compressor motor based on the pressure in the compressor tank. The pressure switch can also be used to adjust the cut-in and cut-out pressures.
How to adjust air compressor pressure switch
You can adjust the pressure switch using the different adjustment screws available on the switch. For further details, check out the air compressor pressure switch adjustment article.
What are some of the best 175 PSI Pressure Switches?
Check out the article on the best 175 PSI pressure switches.
