Air compressors can be categorized in different ways, from their capacity to their pressure limits. However, on of the most popular way to categorized air compressors is based on their design and how they compress air. A fixed compressor can be impressive beast, but they are also comparatively large in size and heavy.
Since, compressors are available in a wide range of sizes and styles, choosing the right air compressor for you is really a matter of how it will be used and your personal choice. Lets find the answer of following stuffs before going any further:
- Where will you be using your compressor?
- Is there a ready electrical supply?
- Will you be working in confined or unventilated areas?
- Which tools will you want your compressor to operate?
Most air compressors have specific requirements for volume and pressure, while compressors are rated on the following four factors:
- PSI – Pounds per Square Inch: PSI is the unit of measurement that a compressor delivered. The higher the PSI, the further the air can be compressed – which means a larger volume of compressed air can be stored in the tank.
- SCFM – Standard Cubic Feet per Minute: SCFM, also known as CFM, is the volume of air that your compressor can pump in a minute a specific working pressure. Higher CRM ratings mean that the compressor can provide more air – making higher CFM units is more practical for larger applications.
- HP – Horsepower: Horsepower is the unit of measurement that a compressor motor produces. Higher horsepower engines means it produces greater PSI and capable of carrying a heavier workload.
- Tank Size: Compressor tank size are measured in gallons. Units with more powerful motors and larger tanks can generate higher levels of PSI for longer amounts of time which is able to provide greater power to your air tools.
Air compressors can be classified in two broad categories depending on the manner in which pressure energy is imparted to the air. These are: Positive Displacement Compresors and Roto-Dynamic Compressors.
Positive Displacement Compressors:
While talking about Positive Displacement Compressors, air is physically trapped between to relatively moving components and forced to occupy lower volume, thereby increasing its pressure. These machine can be further divided into Reciprocating and rotary compressors.
1. Reciprocating piston compressor:
Reciprocating piston compressor also known as reciprocating air compressors or piston air compressors, which are interchangeable terms. In the reciprocating compressor, compressing and displacing element is a piston having a reciprocating motion within a cylinder. Now a days Reciprocating piston compressors are the most common machine on the market. some common type of Reciprocating piston compressor are Single-acting cylinder (head end) compressors, Single-acting cylinder (crank end) compressors, Double-acting cylinder, and Diaphragm compressors, etc.
2. Rotary positive displacement compressors:
Rotary compressors are a type of positive-displacement machine in which compression of the fluid is effected directly by a rotor and without the usual piston, connecting rod, and crank mechanism of the reciprocating compressor. The two most common types of rotary positive displacement compressors are: Screw compressors, Vane type compressors.
In Roto-Dynamic type of compressors, energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor (unlike a positive displacement pump, in which a fluid is moved by trapping a fixed amount of fluid and forcing the trapped volume into the pump’s discharge). Most common types of Roto-Dynamic compressors are: Centrifugal compressors, Axial flow compressors, etc.
Axial flow compressors are rotating, aerofoil based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have a significant radial component on exit.
Based on the aspects, the air compressors are also classified on the following terms:
- Number of stages (single-stage, 2-stage and multi-stage)
- Cooling method and medium (Air cooled, water cooled and oil-cooled)
- Drive types ( Engine driven, Motor driven, Turbine driven, Belt, chain, gear or direct coupling drives)
- Lubrication method (Splash lubricated or forced lubrication or oil-free compressors)
- Service Pressure (Low, Medium, High)
Different types of Air Compressor Grades:
We should take into consideration the purpose of an air compressor while choosing from the three types. A big range of air compressors is available in the marketplace, from portable and consumer models to those intended for contractor and also for commercial use. In general, unless you plan to use air compressors at garages or work sites, You need to focus your search on consumer and portable models.
Another big decision comes in the power source of the device, specifically, oil or electricity. Again, if you intend mainly for on-the-road use, you must focus the search on petrol-powered devices. While the prices are vary, experts recommend is to purchase an air compressor from a reputable best brand over seeking to save a few dollars on a lesser-known brand.