How Does A Reciprocating Air Compressor Work?

By David S. Chang

As compressed air powers operations in industries such as manufacturing, refineries, chemical plants, and refrigeration, it becomes vital to understand how air compressors work. The reciprocating compressor is the most common type, so you must learn all about its working cycle.

Typically, the machine runs on electricity, diesel, or gas engines, depending on the fuel type you choose. Let us explain the steps of its working process in detail.

Understanding the parts and components

First things first, it is important to understand the parts and components of the machine. The machine uses pistons and crankshafts for air compression. It also has a cylinder, which acts as a chamber where the air gets compressed. There are two valve openings- the suction valve and the discharge valve.

The air enters the cylinder through the suction valve, and compressed air exits it through the discharge valve. The crankshaft is run by an external motor to start the machine.

Step 1: Intake cycle

When you turn on the motor of the compressor, the engine rotates the crankshaft. It sets the pistons in an up and down motion. The motion creates a vacuum between the cylinder head and the piston top, and air makes its way into the cylinder via the suction valve. When the crankshaft goes halfway through a full rotation, it pushes the piston upward to start the air compression cycle. The air pressure in the cylinder increases until it surpasses the resistance of the discharge valve. Once it happens, the discharge valve opens, and air moves from the cylinder into the storage tank.

Step 2: Unloading cycle

The compressor has a pressure control device that senses the air in the receiving tank. Once it reaches the high-pressure threshold, the device signals the beginning of the unloading cycle. The Reciprocating Air Compressor may unload fully or partially depending on its design.

The pressure level lowers gradually, and the control device again signals the compressor to re-start when it reaches a pre-determined load point. The compressor initiates the compression cycle to build the pressure again.

Step 3: Duty cycle

The duty cycle of the machine is calculated by comparing the time taken by the compressor to load with the time it runs when completely unloaded. It is vital to ensure that your compressor operates within duty cycle limits, which is typically 20 to 30% of the full-load time for most machines.

Pressurizing your compressor beyond its capabilities causes premature wear and tear and decreases its service life.

Lubrication and cooling

Apart from the steps of the compressor’s working cycle, lubrication and cooling also play a key role in the entire process. In some machines, the engine pump shares lubrication with the compressor to keep the system functioning properly. Further, the lubricant also works as the cooling source for the system.

Cooling is crucial to the maintenance and longevity of the compressor. You have to make sure that lubrication is changed according to the recommendations to keep the equipment performing optimally.

Now that you understand the working of a reciprocating compressor, you can do your bit for extending its lifespan and ensuring optimal performance. Even small measures such as taking care of the duty cycle and staying ahead of lubricant changing schedules can make a difference.

David S. Chang

Award-Winning Entrepreneur, Wealth Manager and CEO | Chief Editor, Author, Keynote Speaker, Consultant | Political Consultant | Army Officer National Guard | Living To Fulfill Needs, Solve Problems, and Live Passionately!


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