Air Compressor Pressure Switch Adjustment – A Complete Guide

In this guide, we will talk about the air compressor pressure switch adjustment steps along with the different types of adjustments. We will also look into the risks and dangers involved and how to avoid them. After reading this you will be the expert about how to adjust the pressure switch.

Why adjust pressure switch settings

The pressure switch of a compressor is set to default recommended settings by vendors and adjusting it is not always recommend. Yet there are times when you would need to change these settings. For example, when you buy a new switch to replace the old one. In that case, you would need to adjust the switch settings to match your compressor’s recommended settings.

Similarly, you would also want to change the settings if your pressure requirement is less and your air compressor’s pressure capacity is more. For example, if your air compressor can provide 120 psi but your requirement is only 100 psi.

In that case, it is better to lower your cut-out pressure to 100 psi in order to save your compressor more work. It will reduce energy costs, maintenance, and improve your compressor efficiency.

Risks and Dangers in adjusting the pressure switch settings

As the cut-out pressure can be adjusted, you might think of increasing the pressure to get more power from your compressor. This is possible but there are risks involved.

You need to check your compressor’s safety rating and make sure you do not exceed the maximum pressure that your air compressor tank can bear. Trying to get more pressure from your compressor will certainly increase your energy cost but more importantly, it can simply destroy your compressor pump.

In the worst case, it can be deadly as the air compressor tank might explode. Therefore, be extra cautious when increasing the cut-out pressure.

Normally, a safety valve in compressors releases the pressure from the tank in case it raises up to a dangerous level but the best thing would be to stick with the factory default settings when it comes to cut-out settings.

Pressure Switch: Cut-in And Cut-out Pressure

It is important to understand the cut-in and cut-out pressure before adjusting the switch.

These are the two pressure levels at which the switch turns the air compressor on and off.

The cut-out is the maximum pressure that the switch allows in the tank. The switch will turn off the compressor motor as soon as the cut-out pressure is reached in the tank.

The cut-in is the minimum pressure to be maintained in the tank by the switch. As the pressure drops to a cut-in level in the tank, the switch will start the motor.

For further understanding consider the following simple cycle.

1. As the air compressor starts, it compresses the air and the pressure inside the tank keeps rising.
2. When the pressure inside the tank rises to the cut-out level, the switch stops the compressor’s motor by cutting its power flow.
3. The pressure inside the tank keeps dropping as no more air is compressed since the motor is shut down.
4. When the pressure inside the tank drops to the cut-in level, the switch starts the motor that, in turn, starts compressing more air, rising the pressure level in the tank until it reaches the cut-out level. At this point, this cycle goes to step 2 and continuously repeats as long as the air compressor is operational.

Pressure Switch Adjustment Types

Air compressor pressure switches come in different designs and models varying in their functionality. Some are non-adjustable and simple while others are flexible and allows pressure adjustment.

Below are the different types of pressure adjustments that different types of pressure switches can provide.

1. Range adjustment
2. Differential adjustment
3. Cut-in & Cut-out adjustment

Please note that all these adjustments might not be available on every air compressor pressure switch.

1. Range Adjustment

If the cut-in pressure setting on a switch is 90 psi and cut-out pressure is 110 psi. You can change this range to either 80 psi to 100 psi or 100 psi to 120 psi. Note that the difference in the cut-in and cut-out will always stay the same, 20 psi.

Please note that the default pressure range (cut-in pressure to cut-out pressure) of a pressure switch is set by the vendor and is normally written on the packaging or casing.

The range adjustment screw on the pressure switches allows you to change the cut-in, cut-out range.

2. Differential adjustment

The difference between the cut-in and cut-out pressure is called pressure differential. In differential adjustment, the cut-in pressure can be increased or decreased on the pressure switch, changing the pressure differential.

For example, on a 90 psi (cut-in) to 110 psi (cut-out) range pressure switch, you can change the cut-in to either 80 psi or 100 psi while keeping the cut-out at 110 psi.

The differential screw on a pressure switch is used for this purpose.

3. Cut-in & Cut-out adjustment

Some pressure switches allow both the cut-in and cut-out to be adjusted along with range adjustment and differential adjustment. Separate screws are provided on these switches to adjust the pressures.

How To Adjust Pressure Switch?

Before adjusting, it is important to identify the type of pressure switch and what type of adjustments does it provide. Following is the step-by-step guide about adjusting the pressure switch.

Initial Steps (Applies to all types of adjustments)

1. Unplug your air compressor
2. Remove the cover from the pressure switch

1. Range Adjustment Steps

In the case of range, adjustments follow the below steps after step 1 and 2 above.

1. Find the range adjustment screw on your pressure switch.
2. Turn the range adjustment screw clockwise to increase the cut-in pressure and cut-out pressure. Moving the screw counterclockwise will decrease both the pressures. As discussed earlier in the article, it will change both the cut-in and cut-out pressures simultaneously at the same time.

2. Differential adjustment Steps

Follow the following steps for differential adjustment

1. Find the differential screw on your pressure switch.
2. To increase the cut-in pressure, move the differential screw clockwise. To decrease the cut-in pressure, move the screw counterclockwise.

3. Cut-in & Cut-out adjustment Steps

1. Find both the cut-in as well as cut-out screws on your pressure switch.
2. Move the cut-in screw clockwise to increase the cut-in pressure. Moving it counterclockwise will decrease it.
3. To increase the cut-out pressure, move the cut-out screw clockwise. Similarly, moving it counterclockwise will decrease the cut-out level.

Final Steps (Applies to all types of adjustments)

1. Start your air compressor to verify your new settings.
2. To verify the new cut-out pressure, let your air compressor run until it reaches the cut-out pressure you have set. You can check the current pressure on the pressure gauge on your compressor.  If the compressor motor stops at your desired pressure, you have successfully reset your new cut-out pressure.
3. For verifying the cut-in pressure, drain your compressor until it reaches the newly adjusted cut-in pressure that you have set. The compressor motor would start on the new cut-in pressure if it is properly set.

Caution: If you set the cut-out pressure too high and the air compressor keeps running without stopping, the safety valve may fire or you may end up with a burnt motor. It is also possible that the tank might explode. Unplug your air compressor immediately if the pressure rises up to a dangerous level.  Also, be very careful with increasing the cut-out pressure.