Air compressors are pneumatic devices that convert power (normally using a gasoline or diesel engine, or an electric motor) into the potential energy present in pressurized (compressed) air.
There are multiple methods that air compressors can use to force an increased amount of air into storage tanks, thereby elevating the pressure. As soon as the tank pressure reaches its upper limit, the compressor automatically switches off.
This compressed air will remain in the tank until it needs to be used. The energy present in compressed air has a wide variety of uses; these applications use the kinetic energy that is produced as the air releases and the tank pressure goes down.
Once the pressure reaches the lower engineered limit, the compressor will turn on once again and start pressurizing the tank. Air compressors should not be confused with pumps: the former can work for any air or gas, while the latter is usable only for liquids.
What is an Air Compressor?
As mentioned, an air compressor by pushing air inside a container and then pressurizes it. Next, the air is sent out through an opening present in the tank. The mechanism is quite similar to that of an air balloon: once you open the balloon, all the air will start to escape and the pressure of the balloon will drop.
An air compressor is driven through an engine that is responsible for creating kinetic energy using electrical energy. This engine works in much the same way as a combustion engine, making use of pistons, crankshafts, heads, valves, and connecting rods.
The pressurized air is then used to operate many different kinds of tools, including paint sprayers, sanders, impact wrenches, and nailing machines.
Types of Air Compressors
There are many different kinds of air compressors, each offering unique features and capabilities. However, the differences are not very significant – generally, air compressors only differ in the way that they handle air displacement.
An air compressor, based on its internal mechanisms, is either categorized as dynamic displacement or positive displacement. Below are the four common kinds of air compressors:
- Centrifugal compressor
- Axial compressor
- Reciprocating air compressor
- Rotary screw compressor
Dynamic Displacement Air Compressors:
A dynamic displacement compressor will use rapid rotating blades to generate horsepower, before limiting the air in order to build up pressure. The compressor will then store the kinetic energy as static.
1) Centrifugal Compressor:
A centrifugal air compressor will use a diffuser to slow and cool down the entering air, thereby creating potential energy. Since centrifugal compressors break the compression process down into multiple phases, they are able to create higher amounts of energy while using relatively low power.
These compressors are also low-maintenance compared to reciprocating or rotary screw compressors, and some types of centrifugal compressors can even create oil-free air. A centrifugal compressor is most suitable for construction sites such as steel manufacturing plants or chemical centers, since they require large amounts of energy.
2) Axial Compressor:
An axial compressor is generally not used for construction, but is instead more common in speed-engines present in planes or ships. These compressors are highly efficient and can attain thousands of horsepower worth of power. However, since they are also extremely expensive, they are primarily reserved for aero-spatial research.
Positive Displacement Air Compressors:
A positive displacement compressor is any compressor that uses air displacement to generate power. Although the internal mechanisms might differ, all positive displacement compressors operate under the same principles.
A cavity present in the machine is used to store the incoming air. This cavity is then gradually compressed, leading to an increase in potential energy and air pressure.
3) Rotary Screw Compressor:
Rotary screw compressors contain internal cooling mechanisms and are extremely low-maintenance, thereby making them one of the most popular air compressor types. Generally, a rotary screw compressor is a large machine that is either lubricated through oil, or operated oil-free.
These compressors produce energy through a pair of rotors that move in opposite directions. These rotors trap the air and create pressure. Thanks to the internal cooling mechanism, rotary screw air compressors can be used in a continuous manner, and can create power ranging from 5 to 400 horsepower.
4) Reciprocating Compressors:
The reciprocating compressor, like its rotary screw counterpart, is quite popular. Reciprocating air compressors are generally used to generate power for smaller projects like garages or house constructions.
One difference between the reciprocating and rotary screw compressor is that the former cannot be used continuously. Other than that, reciprocating compressors have more parts than rotary screw compressors, and these parts require oil lubrication in order to function smoothly.
Reciprocating compressors make use of a piston present in a cylinder; this cylinder displaces and compresses the air, thereby creating pressure. These compressors are available in both multi- and single-stage variations, and the type of variation will define the pressure limits that the compressor can attain.
Key Features of a Good Air Compressor:
1. Oil-Free Pump
This makes sure that the compressed air does not mix with the oil, and also reduces maintenance costs and efforts.
2. Belt-Drive System
A belt-drive system offers quieter and smoother operation, compared to a compressor with a direct-drive system.
3. Thermal Protection
Thermal protection ensures that the motor does not suffer damage caused by overload.
4. Multiple Couplers
This feature allows you to deal with different tasks simultaneously, without having to connect and disconnect the tools.
Make sure that you get all required accessories, including blow guns, nailing machines, and hoses. If you get an air compressor that does not offer these accessories, you will have to buy them separately.
6. Auxiliary Air Tank
An auxiliary air tank helps increase the tank’s air-storage capacity. Generally, auxiliary air tanks are something that you will have to buy separately.
Our Final Thoughts
To sum up, air compressors play a very important role in a large number of industries and projects. We hope that this guide helped you gain a broad but firm idea about air compressors, how they work, and their key types and features.