How Does a Pancake Air Compressor Work?

Pancake air compressors are a form of reciprocating air compressor known for their fuel and energy efficiency. They can be either gas or electrically powered and are known for their light weight and portability, making them particularly popular among construction workers, roofers, dry wallers and carpenters.

There are two main components of a pancake air compressor, which are typically bolted into a square or rectangular metal framework on wheels for ease of transport. The motor sits beneath the compression tank, which doubles as a holding tank. A pressure gauge and release valve sits at the top of the compression tank. One but sometimes two quick release air ports protrude from the side, while an intake manifold sits opposite.

When the motor is turned on, a driveshaft that extends up into the bottom of the compression tank begins to crank. The inside of the compression tank is divided into three chambers. There are two pistons which are sealed away from the other two chambers by means of a heavy plastic diaphragm. One piston is situated beneath each of the two chambers and can push against the diaphragm separating them in order to increase or decrease the volume of space in these two chambers. The wide piston heads, when pressing against this diaphragm look similar to a pancake, hence the name.

The piston beneath the compression chamber retracts, and the piston beneath the holding chamber extends. Without the piston squeezing the compression chamber, it can expand to its full size. This creates a low-pressure suction in the compression chamber that causes air to be pulled in through the intake manifold via a one-way valve. The piston beneath the holding chamber retracts and the other extends, reversing which chamber is being squeezed. This forces air from the compression chamber into the holding chamber, again via another one-way valve. This process repeats hundreds of times per minute, only stopping once the pressure gauge readout reaches the maximum internal pressure, which sends a signal to turn off the engine.

The compressed air can be used to power any number of pneumatic tools connected to the air outputs, and the pancake air compressor will resume functioning to refill itself the moment the internal pressure drops below the maximum.