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2 Key Air Compressor Valves

By In Blog, Tips On March 30, 2018


Air compressors are one of the most widely used appliances thanks to their seemingly endless variety of uses. They play a vital role in a variety of construction projects. For example, it would be hard to imagine a house painter or automotive technician who doesn’t rely on an air compressor on a near-daily basis.

While air compressors may seem relatively simple compared to other heavy-duty appliances, they still require the close coordination of various components. In addition to the tank, motor, and pump, an air compressor utilizes various valves in order to deliver pressurized air. This article will improve your knowledge of air compressor anatomy by discussing two types of valves inside an air compressor.

1. The Unloader Valve

Air compressors are cyclical machines. In other words, they must start up on a regular basis in order to replace the air being consumed by whatever tool you happen to be using. A compressor knows when to restart thanks to an internal pressure switch. When the pressure dips below a preset level, the switch will trigger the flow of power to the motor.

Yet without the unloader valve, the motor may not be able to provide the power necessary to get the pump started because air may still be trapped inside of the pump’s cylinders. This happens because, when the tank’s pressure reaches the desired threshold, the motor will shut down abruptly.

The pistons will remain wherever they happen to be at that moment. Sometimes they are poised at the top of their down-stroke with a cylinder still full of air. This air increases the amount of power necessary to start the pump, and will often keep it from starting at all. That’s where the unloader valve comes in.

An unloader valve releases pent-up air from the cylinders when power stops flowing to the motor. This ensures that the pistons will be able to engage without undue resistance when the motor restarts. An air compressor that struggles to restart may be suffering from damaged or degraded unloader valves. Have a professional inspect and replace them as soon as possible.

2. The Check Valve

An air line connects the pump to the compressor tank. As the pump runs, it pushes air through the air line into the tank. Once the pressure has reached the upper threshold, a pressure switch triggers the pump to shut down. At this point, as discussed above, any air left in the cylinders bleeds off through the unloader valve.

The unloader valve can be found attached to the air line running between pump and tank. The so-called check valve also sits along this section of theĀ air line. The check valve plays a key role in regulating the performance of the unloader valve. Without the check valve, when the unloader valve opened up to bleed air from the cylinder, it would also allow air to escape from the compression tank.

The check valve functions as a sort of one-way mechanism. It allows air to flow to the unloader valve from the pump while preventing it from flowing backward out of the tank. This allows the tank to maintain its pressure while also allowing proper functioning of the unloader valve.

A bad check valve will allow air to escape from the tank when the pump shuts down and the unloader valve opens. If you have noticed your pressure gauge plunging at such times, be sure to have a professional inspect your check valve. For more information about how to prevent this and other valve problems, please don’t hesitate to contact the air compressor experts at Compressor-Pump & Service, Inc.


About the Author

enelson@compressor-pump.com

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