Ideally, an air compressor is a tool that is responsible for converting power into potential energy which is stored as compressed air. It is a recent innovation as many tools used to draw their power from a centralized source where power would be transferred in different method depending on the tool being powered.
Today, however, the air compressors are found almost everywhere. You will find them in gas stations where they are used to fill inflated tires or in places where cars are serviced. They are also common in workshops and factories, powering tools such as drills, sander, spray guns, and nail guns.
They have also found use in homes and their compact size and also the fact that they require a relatively small motor gives them a competitive advantage over power sources. They are also generally durable, portable and they do not produce a lot noise.
Classification of Air Compressors
Air compressors are classified into two broad categories:
According to amount of pressure delivered i.e.
- Low pressure- These compressors have a discharge pressure of not more than 150 psi (pounds per square inch).
- Medium pressure- Compressors under this category have a discharge pressure that ranges between 150 psi to 1000 psi.
- High pressure- These compressors bears the maximum discharge pressure of above 1000 psi.
According to the design and principle of operation
- Reciprocating air compressors which use pistons to compress air for storage in the preferred mode.
- Rotary screw air compressors which just as the name suggests, they use screws to compress air for storage until it is needed.
So How Does An Air Compressor Actually Work?
Any air compressor has two parts; the compressing system itself and the source of power. Depending on the type of compressor, the compressing system may be either a piston or rotating screw while the power source could be anything from electric motor, petrol motor and other sources of energy.
As the name suggest, an air compressor works by compressing the atmospheric air for storage which is then used as per the needs. It applies the principle of compressed air which tends to decrease in volume while the pressure increases.
The pressure level is controlled by a knob which is set to automatically shut off when pressure in the storage tank reaches maximum level. This is turns cuts the supply of atmospheric air to the compressor. Similarly, when the pressure level falls the knob shuts on allowing more air in and the cycle continues.
Reciprocating Piston Compressor
The most popular method of compressing air is using the reciprocating piston compressor. This compressor uses the principle of pistons which are in constant motion to draw air into the air chamber. Air is directed into the chamber by one-way valves where it is regulated by the piston positioned at the base of the chamber. The piston is stroked down to allow air into the chamber and stroked up to direct the air into the storage area.
A standard reciprocating piston compressor will have a piston, crankshaft, connecting rod, cylinder, and a valve head. The valve head has both the inlet and outlet valves which allows in air and discharges it respectively as directed by the piston.
Rotary screw air compressors
Rotary screw air compressors use screws to compress air and their structure entails vital parts that are responsible for the whole process of compressing air into power for various applications. These are;
1. Inlet Valve
This is where the whole process starts. Any rotary screw compressor will have a small opening (valve) which opens to allow air in for pressurization and subsequent transformation into power for use in various applications and tools.
Rotors are the basis of a rotary screw air compressor and it has two of these rotors. These rotors direct free air molecules in a sequential manner into the compressor and turns them into a pressurized form. The pressurized air is in turn converted into energy which is used to power various tool and applications in lieu of conventional sources of power.
3. Solid Housing
Rotary screw air compressors are enclosed in a solid and tight casing which helps to keep trapped air tight as well as eliminate leakages. This leads to a seamless compression process which involves faster transmission of air between the inlet valve that ushers in air for compression and the outlet valve.
4. O-ring Seal
In addition to the tight casing, the inlet valve is reinforced with special seals, O-ring seals, which make sure the valve lets in as much air as possible with no risk of leaks.
5. Thrust Bearings
The embodied bearings bring about a constant movement of air and also they ensure that all other part of the compressor work in a consistent manner which translates into maximum compression of air.
This key feature ensures that the compressed air is clean and free from air-bound oil particles and moisture which can create a great problem to certain applications especially the ones that involves drying, painting among others.
7. Outlet Valve
To achieve the whole objective of compression, the pressurized air should exit the compressor without losing its temperature or volume. It should also not leak through any openings and that is why the compressor has a very tight outlet valve to ensure that all compressed air is channeled to the intended tools.
Cooling an Air Compressor
An air compressor may require occasional cooling to help get rid of excess heat due to constant heating. This can be done by using water or just air while others compressor are cooled by oil.
Applications of Air Compressors
Air compressors have many applications both large scale and small scale which includes;
- Refilling gas cylinders
- Powering pneumatic tools such as jackhammers
- Filling inflated tires
- Filling HPA (high-pressure air) tanks
- Supplying HVAC equipment with clean air
- Powering large-scale industrial applications among others
It is important to perform a regular maintenance to ensure that that the compressor works efficiently. The compressor should be monitored for any leaks, operating temperatures, and checking the fittings to establish if they require any adjustments for optimal performance.