Air Compressor | What are the Types of Compressor?

The main objective of this article is to explain the air or gas compressor and different types of air compressors. Compressors are essential in almost all industries.

What is a Compressor?

A mechanically operated machine that rises the fluid pressure by reducing its volume is called a Compressor. If the compressor uses gas as a working fluid, it is called a gas compressor. While if the air uses as a working fluid, it is called an air compressor. Naturally, in a compressor, the compressed air gas rises the temperature.

An air compressor is also a specific kind of machine that operates with compressed air aid and is used in different industries. The air compressor has gained worldwide recognition after its discovery in the year 1875.

With the help of the air compressors, people could save their time and money in almost every work. It was even found that these devices had a great impact on the lives of the people. A lot of work was taken up by the people who were able to reduce their work, and this has led to a major increase in the productivity of the people and their performance levels. This is the main reason why the demand for compressors has gone up drastically. 

Air Compressor

The working of a compressor is like a pump. But their work is a little bit different. But both pump and compressor mechanical devices increase the pressure of the fluid.

How Does A Compressor Work?

The basic working concept of gas or air compressor can be easily understood. Basically, it works by changing the volume of the gas or air.  It uses a piston or diffuser to increase the pressure of the working fluid. When the working fluid enters into diffuser then it changes the speed of the fluid into pressure energy. In this way, a compressor compresses the gas or air. After the compression process, the compressed air is transformed into a storage tank.  Many industries have used compressors to increase production, which has led to the development of many new industries.

Nowadays, there are many companies that manufacture and supply air compressors to different industries. The manufacturing of these machines was initially done using wood, but now many modern techniques and materials are being used to manufacture them. Many countries are using air compressors for their advantages. They are making use of these machines to save their precious time, energy, and money.

Types of Air Compressor

The most famous types of air compressors are given below in detail.

compressor types

The air compressor has two main types that are:

  1. Positive Displacement Compressors 
  2.  Dynamic Compressors

These two types further divide into more different types that are given below.

1) Positive Displacement (PD) Air Compressor

It is a very famous type of air compressor. The principle of the positive displacement compressor is straightforward. These compressors reduce the volume of the compression chamber by introducing air into the compression chamber through the suction air. It compresses the air until the air pressure reaches according to the requirements. The compressed air is then blown out of the valve at nominal pressure to provide a flow of air.

Another definition of a PD compressor is that a compressor that works by drawing a distinct amount of gas or air from the inlet of the compressor and then forcibly exit it from the outlet of the compressor is called a PD compressor.

These compressors have further types that are given below:

Positive displacement compressor types

1.1) Reciprocating Compressors

These types of air compressors use a piston that pushes by a crankshaft. The reciprocating air compressor uses a piston that moves at a constant speed to pull the air in then compresses it. Typically, one drive of the piston sucks the air in the cylinder and the other drive squeezes it.

The type of reciprocating compressors that is small in the 5 to 30 horsepower range are mostly found in the applications of automobiles and are generally used for intermittent operation. Large reciprocating compressors are more than 1000 horsepower and are commonly used in petroleum applications and large industrial applications. There also use for applications like chemical plants, industry, oil refineries, and including natural gas processing and delivery.

Advantages:

  • These are easy to maintain
  • These are best for applications that need high pressure
  • Very highly efficient and flexible
  • It has a simple design

Disadvantages

  • These compressors produce high noise
  • It is a highly vibrating equipment
  • It has a large size

1.2) Rotary Screw Compressors

These are the most common types of air compressors used nowadays. The air sucks into the compressor, closes the openings, and compresses the air with the help of two rotors that rotate continuously and run via the cavity. With each revolution, the air pressure gradually increases until it touches the desired pressure.

screw compressor

The classification of the screw compressors depends on the type of gearbox, the method of cooling, and the stage. These types of air compressors generally manufacture in dry variety, water and oil flooded. The rotary compressors efficiency is very dependent on the air dryer. Screw compressors have few components, high efficiency, large capacity, simple structure, voltage spikes, and low vibration and can run at low speed to adjust power.

Advantages:

  • These don’t use a piston
  • These have higher than piston compressors
  • This compressor gets less space for installation
  • It has less vibration and types than other types
  • It has high reliability
  • Highly efficient
  • It has a long service life

Disadvantages:

  • These have a high cost than other positive displacement compressors
  • These also need high maintenance
  • High precision
  • It needs for special equipment processing
  • High service cost

1.3) Ionic Air Compressor

Ionic compressors are also called ionic liquid piston pumps. This is a liquid ionic piston-based hydrogen compressor, not a metal piston like a metal diaphragm piston compressor.

Advantages:

  • It doesn’t require a seal and bearings
  • It has a long service life
  • This type decreases energy consumption
  • It requires low maintenance

1.4) Rotary Vane Compressors

The rotary air compressor is another well-known compressor. Two asymmetrical rotors (also known as spiral screws) use for the compression of the air.

Rotary Vane Compressors

The rotary vane gas compressor consists of a rotor with a large number of vanes. These blades fix into the radial groove of the rotor—the rotor fixes in a housing with a rounder or more complicated structure. When the rotor rotates, the vanes move inward and outward of the slot and continue to contact the housing outside the wall. Thus, the rotor blades create a series of maximizing and minimizing volumes. This compressor is the oldest technology of compressor.

These use for the applications such as for tire inflation in tires and wheel shops, dry cleaning and paint pumps, etc. 

Advantages:

  • It has an easy design
  • Highly efficient
  • It has a low initial cost
  • It has a compact size
  • Simple design

Disadvantages:

  • It uses for limited applications
  • It highly vibrates during the working
  • This compressor has a high number of moving components
  • Due to many moving parts, it has a high maintenance cost

1.5) Rolling Piston Compressor:

The rotary piston of this type of air compressor acts as a separation between the rotor and the blade. This piston pushes the gas towards the fixed vanes. On the same shaft, two of these compressors can fix to decrease noise and vibration and increase capacity. A springless version knows as a swing compressor.

Rolling Piston Compressor

This gas compressor is more efficient than a reciprocating compressor because less space is lost between the piston and the compressor housing. With a given capacity, the volume of the rolling piston compressor reduces between 40% and 50%, and the weight increases. It has fewer vibrations, fewer parts. It is more reliable as compare to the reciprocating compressor.

Advantages:

  • It has a low maintenance cost
  • It has a low initial cost
  • Simple control

Disadvantages:

  • It has low efficiency
  • It is highly noisy
  • These compressors have low efficiency

1.6) Scroll Compressor

Scroll compressors also called scroll vacuum pumps and scroll pumps. These types of air compressors use two offset spiral blades to compress or pump to different fluids like air or gases and liquids. The shape of the blade can be a mixed curve or Archimedean spiral. They work smoothly in a lower capacity limit than other types of compressors. It is quieter and more reliable.

Scroll Compressor

Usually, one scroll is rigged, but the other is eccentric and does not rotate, pumping, and trapping, or squeezing pockets of the available air between the scrolls.

These use for the applications such as residential, air conditioners, marine containers, fruit and food refrigeration, vacuum pumps and truck transportation etc. 

Advantages:

  • It has a low pulsation of gas
  • Low weight
  • These have quiet operation
  • There is no use of piston
  • It has only a few moving components
  • It has high durability

Disadvantages:

  • It has a low capacity
  • These have a high cost

1.7) Diaphragm Compressor

This type of air compressor is a kind of conservative piston compressor. In these types, gas or air compression causes when the flexible diaphragm moves, not the intake component. The forward and backward motion of the diaphragm handles with the help of a crankshaft and a rod mechanism. When there is a need for gas compression then only the compressor box and the membrane makes contact with the gas. The degree of bending and the material of the membrane affect the life of the device.

diaphragm compressor

Silicone or rubber diaphragm compressors can withstand very high deflection depths. Still, due to the low strength of these compressors bounds their use in low-pressure applications and requires replacement if the plastic becomes brittle. These use in many applications like compressed natural gas (CNG) and hydrogen plants. 

Types of Dynamic Air Compressor

Types of dynamic compressors are given below.

types of dynamic compressor

2.1) Centrifugal Compressors

It includes in the most famous air compressor types. It uses a rotatory impeller or a disc in the housing to push the gas or air towards the blades of the impeller. The impeller blades raise the speed of the gas. The diffuser transforms the energy of the gas speed into pressure. After that, the gas is transferred to the desired location.

These compressors mainly utilize for constant, fixed applications in industries like petrochemical plants, natural gas, chemical plants, and oil refineries processing plants. Its applications range from 100 hp to thousands of hp. With various upgrades, high outlet pressures above 6.9 MPa (1,000 psi) can be achieved.

centrifugal compressor

These kinds of air compressors widely use in air conditioning systems and large refrigeration.

Advantages:

  • It has low weight
  • It has an easy designing
  • Easy to maintain
  • Energy efficient
  • These are reliable

Disadvantage:

  • Not suitable for high compression applications
  • It has choking, stalling, and surging problems
  • It produces a limited amount of pressure

2.2) Axial Air Compressors

The axial compressor is a type of dynamic compressor. These are very famous types of air compressor. These use when compact designs or high flow rates needed. The axial compressor uses a series of fan-shaped air blades to compress the liquid gradually. 

In this type, the wings arrange in pairs, one in a stationary row and the other rotating row. A rotating blade of air, also known as a rotor, accelerates the liquid. Fixed blades (also called vanes or stators) slow down and redirect the direction of fluid flow, arranging the rotor vanes for the next step.

Axial Compressor components

These compressor types require a large number of components. And also, they have high material quality. Therefore axial compressors are expansive. These types of compressors use in CNG stations and all gas turbines.

Advantages:

  • It is very efficient than other types of compressor
  • It has a high-pressure ratio
  • It is best for multi-staging

Disadvantages:

  • It is relative expansive
  • It has a difficult manufacturing
  • These compressors have high weight

How to use an Air Compressor?

The operator of the air compressors needs basic skills and training to operate them. First, read the instruction manual and make a maintenance list according to the instructions of the manufacturer. Then, make a chart for the use of your air compressor and operate it according to that. Following are the basic steps that will be helpful to use an air compressor. 

1) Make Sure Safe Operation

It is very important that do not immerse the electrical components of the air compressor in water and keep them away from the water. Doing so could cause an electric shock. Typically, the operator keeps the electric discharge valve away from wet surfaces. If pneumatic air compressors are activated, then oil changes and refueling can raise safety concerns. And also, use the machine while it cools down.

Also, do not neglect to plug the compressors into an electrical outlet equipped with a lightning rod. The fire extinguisher should also be placed in an important location near the equipment.

The inlet pressure should not exceed 90 PSI unless the internal pressure of the compressors is high. Because this higher pressure of the air may affect the functioning of the air tools. Therefore, it is very important to understand the air needs of air distribution systems, dryers, tools, and other equipment.

2) Tight the loosing parts

Check and tighten loose parts in fittings and connectors because they may loose due to vibration of the compression system. Generally, vibration loosens nuts, screws, and bolts. Therefore, take a look at these parts and tighten them if they are loose.

3) Wear PPE (Personal Protective Equipment)

Always wear personal protective equipment (PPE) before operating the air compressor. Before operating the equipment, the operator should boot, goggles, hard hats, and wear gloves. In the event of an accident at the workplace, PPEs may prevent the worker from any severe injury. Proper PPEs also reduces the risk of environmental damage.

4) Check the oil level of the Air Compressor’s Pump

It is very important to check the oil level of the oil-lubricated compressors before operating them. This will help you in the prevention of equipment damage. In contrast, if you have an oil-free air compressor, you don’t need to perform a regular lubrication inspection. Make sure the power is turned off before eliminating the oil filter plug.

5) Connect Pneumatic Tools

When using the quick-connect accessory, pull and release the spring collar and securely connect it to the compressor. Make sure the pneumatic tools are properly connected to the compressor’s air hose. Ensure that there should be no leakage of air from the pneumatic tool’s inlet valve.

6) Drain the moisture from Air Tanks

As the tank gets moist from the atmosphere, the compression holds the vapors. This situation often occurs with air compressors in humid weather. Therefore, it is essential to drain the moisture from the air tank for the proper working of the equipment.

After completing work, the operator can unlock the drain valve under the air tank to drain the moisturized air. It is necessary to release the air pressure in the tank before releasing the water regularly.

7) Inspect Oil Level

Inspect and replace the lubricating oil of the compressor after each use. Because oil is very important for the piston of your equipment. This oil helps the piston to move forward and backward.

If you do not adequately lubricate the piston then it may damage. The manufacturer also recommends that the operator refuel the oil lubrication pump within 500-1000 operating hours.

8) Fill Air Tank

Almost all the compressors have a drain valve for the release of the air or gas. Therefore, make sure the drain valve of your air compressor.  If it also has a drain valve, turn it off with a wrench before filling the air tank. After closing, Turn on the power. Instead of using the compressor right away, let the pump run for a few minutes.

Check the air pressure gauge to see if the compressor will automatically shut down when the air pressure reaches 115 PSI. The extreme operating pressure can fluctuate depending on the air compressor’s model. The maximum pressure rating for some DEWALT products is 150 PSI.

9) Regulate the Air Control Valve

You can use the pneumatic power of the air tools to customize the air valve regulator according to your requirements. Typically, turning the air control valve clockwise increases the air pressure. Basically, this control valve uses to stop, decrease, or increase the air or gas pressure. 

Follow the manufacturer instructions in the product manual to understand the direction in which the control valve will increase air pressure. In addition, though, careful attention to the pressure gauge can provide the correct air pressure for the tool.

10) Ensure More Checks

The separator elements of the compressors can regulate excessive oil consumption. Therefore, the operator should continuously monitor the working of the air or gas compressor. In addition, the separator element must change after the machine has been running for approximately 1,000 hours.

How to repair an air compressor?

If the air compressor starts normally at the beginning of the day but then stops and makes a loud hum on further attempts, the “unloader” valve is defective. If you want to repair your then follow the below-given steps to repair it:

  • Firstly, find the valve position on the compressor. This valve usually locates below the pressure switch. After finding this component, you can determine the type of unloader valve that can be used to replace it.
  • After finding the defective valve and ordered a replacement part, the next step is to repair the compressor.
  • For safety purposes, the device must be switched off completely before starting the repairing process.
  • Next, loos the drain valve under the compression tank. When the drain valve is released, the air compressor will be depressurized and can easily repair.
  • As soon as the air compressor is switched off and safely decompressed, the replacement process can be carried out. After decompressing, remove all cables connected with the old valve. You can then install a new “unloader” valve. When installing a new valve, then secure it tightly on its position.
  • After the completion of the installation procedure, turn on the equipment to check the repair of your compressor and check the valve’s performance.

Repair Air Compressor leakage:

If your compressors are not delivering air properly and you feel leakage of fittings then follow the below given steps to repair it:

  • For the confirmation of leakage, make a solution of soap water and pour it on the fittings. If bubbles are coming out from the fitting, it means the fitting is leaked.
  • Turn off the air compressor
  • Depressurized the air tank
  • Emilite the fitting from where bubbles were producing.
  • Get the Teflon’s plumber tape and wrapped it around the leaking fitting.
  • After this process, turn on the equipment and check performance.

Applications of  Compressor

1) It uses in the natural gas plant for gas processing purposes.

2) Uses in petroleum refineries.

3) Petroleum plants.

4) The air compressor uses in the refrigerators to remove heat from refrigerant cycles.

5) It uses in gas turbines.

6) Some types of jet engines use the compressor.

7) Uses in the diving cylinder to compressor and provide gas for breathing purposes.

8) Compressors use in heat pumps and first pistons.

9) It uses in submarines.

10) Compressor uses in oil refineries.

What is free air delivery in an air compressor?

Free air delivery is a volume of air that a compressor took in from the atmosphere, compressed, and discharge into the receiver, tanks, pipes, or air house.

The concept of free air delivery is often used to compare the fluids handling capacity of the compressor. For example, if you want to calculate the fluid handling capacity of several compressors to be compared, you have to compare at the same level (i.e., under the same conditions (pressure and temperature)). Therefore, free air delivery is the amount of air supplied at the outlet but at inlet conditions. To compare multiple compressors, you can use the NPT as an input condition and calculate the free air supply for each compressor under those conditions. These compressors have more free air delivery and, therefore, will have maximum liquid handling capacity.

The V1 is the free air delivery of the compressor.

What is the difference between pump and compressor?

       Compressor                 Pump
The air compressor has compressible working fluids such as gas. The Pump has non-compressible working fluids such as liquids.
It Increases the potential energy by compressing the working fluid. It increases the kinetic energy of the working fluid, which further raises the pressure energy.
There is a change in volume from inlet to outlet. In pumps, there is no change of volume from inlet to outlet.
There must be a pressure change during working. The pressure change is not compulsory.
It has storage capability after compression. It doesn’t have storage capacity after pumping.
Compressors have more cost than pumps. It has a low cost.
It has High ΔP and Low Q. The pump has Low ΔP and High Q.

Why is a compressor used for the refrigeration cycle?

All practical power-consuming or power-producing devices work on a cycle. The refrigeration cycle consists of 4 processes (heat addition, heat rejection, compression, and expansion). After combining these processes, we get continuous work (cooling in this case). Therefore, a compressor is an essential equipment for refrigeration and air conditioning units.

Basically, a compressor’s principal objective is to surge the temperature and pressure of refrigerants in the refrigeration cycle. A compressor has two objectives in the refrigeration cycle that are given below:  

refrigeration

  • One is to increase the pressure and temperature of the refrigerants to allow the flow of refrigerants in the system. Because without pressure difference, there can’t be any flow of Refrigerant. It converts the wet or dry saturated vapor to the wet, dry saturated, or superheated vapor.
  • Now second is that it helps in liberating the heat gained in the evaporator to the atmosphere. Because at a lower temperature, the heat can’t be rejected to the atmosphere. Now when the pressure and temperature of the Refrigerant increase to a value greater than atmospheric temperature, then the heat transfer takes place from the refrigerant to the atmosphere.

Thus, it liberates heat gained in the evaporator and also the heat gained in the compressor.

Therefore, we use a compressor in the refrigeration. We can replace the compressor with some other device in some special type of units like in the Vapor Absorption Refrigeration System (VARS). But these types of systems are not very much used practically.

In this article, I deeply explain the air compressor and its different types. So, I try my best to explain this topic. If you need any clarification, then please let me know in the comment section. I will try my best to respond to you with the right answer.

FAQ Section

What is a compressor used for?

A compressor uses to transfer the air or gas from one location to another by increasing the pressure of air or gas through the compression process. The compressors use for different applications such as refrigerants, fertilizer industries, food industries, and submarines, etc.

What are the types of compressor?

The compressors have two major types that are:

  • Rotary Compressors
  • Centrifugal Compressors
  • Screw Compressors
  • Diaphragm Compressors
  • Axial Compressors
  • Rotary Vane Compressors
  • Scroll Compressors

What is the definition of compressor?

A compressor is a machine that uses to transfer the fluids from one location to another location by increasing their pressure.

Which compressors is used in AC?

A reciprocating compressor is the most famous type that uses in AC. A piston inside the AC compressor moves forward and backward to suck and compress the air.

What is the function of a compressor in sound?

In a sound system, a compressor uses to reduce the dynamic range by compressing the sound.

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