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Air Compressor : Basics, Types, Working and Operation

What is an air compressor? It is a mechanical device that increases the pressure of a gas by reducing its volume. These are regarded as similar to pumps. Both increase the fluid pressure, and both can transport the fluid through a pipe. As we know, gasses are compressible. The compressor reduces the volume of a gas by compressing it. Though the air compressor is not directly connected to the pneumatic system, it plays a vital role in the overall system performance. Electric motors, diesel engines, and gas engines commonly power air compressors. For in-depth knowledge read this complete guide regarding how does an air compressor work and how to run it.

What Does an Air Compressor Do?

Before knowing about how do air compressors work, let’s see some of their applications. Air compressors are mainly used in industries. But here is a list of other uses of an air compressor-

  • Spray Painting
  • Pressure Washing
  • Fountains
  • Scuba Diving
  • Cooling
  • Agriculture
  • Workshops
  • Manufacturing
  • Construction
  • Inflating

How Does an Air Compressor Work?

Air Compressor works by compressing atmospheric air to create potential energy stored in a tank and used later. When compressed air is intentionally released, the pressure increases, transforming potential energy into useful kinetic energy, much like an open balloon. This energy transfer can then be used to power various pneumatic tools. It works the same way as a combustion engine, with a crankshaft, piston, valve, head, and connecting rod.

Types of Air Compressor

According to the pressure delivery, there are three types of air compressor-

  1. Low-pressure air compressor (LPAC)
  2. Medium-pressure air compressor (MPAC)
  3. High-pressure air compressor (HPAC)

LPAC discharge air pressure at 150psi, MPAC discharge air pressure between 150-1000psi, HPAC discharge air pressure above 1000psi.

Based on types of oil contamination, there are two types of air compressors-

  1. Oil Injected Air Compressor: Oil splashes onto the cylinder’s walls and bearings in an oil-injected air compressor. Oil-flooded lubrication is another name for this approach, which is more durable. A piston ring is a metal component on the piston that aids in sealing the combustion chamber. Although this ring can help keep oil out of compressed air, it can still seep into the tank at times.
  2. Oil-Free Air Compressor: Oil-free compressors are lubricated in a special way that lasts for a long time and eliminates the need for oil. Oil-free pumps are a great choice for many industries such as breweries, food production, and pharmaceutical manufacture. They make certain that the air they use in their process or product is free of oil contamination. Oil-free air compressors work better for critical appliances. It is more technically advanced and gives better air than the oil-injected ones. However, the oil-injected air compressors are expensive, loud, and don’t work for a longer duration of time.

According to air compression, there are two main methodologies on which the compressor works. They are-

  1. Positive Displacement 
    • Rotary Screw Compressor
    • Reciprocating Air Compressor
  2. Dynamic Displacement
    • Axial Compressor
    • Centrifugal Compressor

1. Positive Displacement

Positive displacement compressor forces air in a chamber where the volume is decreased to compress the air. The discharge valve opens when the maximum pressure in the chamber is reached, and the air is discharged to the storage tank. The compressor turns off when the pressure in the storage tank reaches the required upper limit. Pressurized air in the tank is used for a variety of purposes. The compressor restarts and begins compressing air when the pressure in the tank reaches its minimum limit.

Rotary Screw

Two internal rotors that rotate in opposite directions provide energy in rotary screw air compressors. The air becomes trapped between the two opposing rotors, causing pressure to build up inside the housing. These air compressors are built for prolonged operation due to the internal cooling system and range in capacity from 5 to 350 horsepower.

Reciprocating Air Compressor

Unlike the rotary screw compressor, the reciprocating compressor is not intended for continuous operation. A reciprocating air compressor has more working components than a rotary screw compressor, maintained with oil for smoother operation. A piston inside a cylinder compresses and displaces the air to produce pressure in reciprocating air compressors. The pressure ranges that reciprocating compressors may achieve vary depending on whether they are single-stage or multi-stage.

2. Dynamic Displacement

A rotating part in a dynamic displacement compressor imparts its kinetic energy to the air and converts it to pressure energy. The centrifugal force is used to transfer kinetic energy.

Axial Compressor

Axial air compressors are often found in high-speed engines on ships or planes rather than construction projects. They have a high-efficiency rate, but they are much more expensive than other types of air compressors. Nevertheless, they can produce tens of thousands of horsepower, so they are primarily used in aerospace research.

Centrifugal Compressor

Centrifugal air compressors delay and cool the incoming air through a diffuser to build up potential energy. Due to the multi-phase compression process, centrifugal compressors can produce a large quantity of energy in a small unit.

How to Run an Air Compressor?


For running an air compressor, you will need 6 important components-

  • Safety glasses
  • Air compressor
  • Instruction manual
  • Oil
  • Power tools
  • Power supply

Step-by-Step Guide on Air Compressor Operation

Step 1: Always wear safety glasses when working with power tools.

Step 2: Assemble the air compressor to the manufacturer’s installation instructions. Then, connect the hose to the regulator valve.

Step 3: Check the oil level and add oil if necessary.

Step 4: Plug the compressor into a three-pronged, grounded outlet. Check to ensure the system relief valve is set correctly. The system relief valve is a safety feature that will pop open if the pressure builds to more than the compressor can handle, preventing system failure.

Step 5: Turn on the compressor to pump up the tank and close the tank drain valve.

Step 6: Connect a power tool to the hose. Adjust the compressor’s pressure to the tool’s specifications and the project you are working with. Never exceed the pressure recommended by the power tool’s manufacturer.

Step 7: Turn off the compressor and unplug it. Disconnect the tool and then the hose when you’re finished. Finally, open the drain valve to drain the water from the tank. Store your compressor away from the elements so it’ll be in perfect working order the next time you need it.

Maintenance of Compressor

Routine maintenance is critical to guarantee that all compressor types work efficiently without leaks. Maintenance includes monitoring and replacing air-fuel management components, lubricant maintenance, draining water from the tank, and changing seals. The instructions in the supplied manual can operate most air compressors.


Air compressors are very recent inventions in regards to the machine age history. But it is one of the most important appliances used in factories and workshops. Each air compressor comes with its own set of advantages and disadvantages. So, choose carefully which one is the best air compressor for your use!