Different types of Positive displacement compressors
Do you know that air compressors deployed at your dentist’s clinic, salon, tattoo parlors, and even at repair shops and airports are mostly Positive Displacement Compressors? They are reliable, cost-effective, and efficient, making them versatile in different industries. Positive displacement compressors have been divided into four major types: Reciprocating Piston Compressors, Rotary Screw Compressors, Rotary Vane Compressors, and Oil-free/Oil-less Compressors. Let’s discuss these compressors in detail:
Positive displacement compressor types
1. Reciprocating Piston Compressors
Reciprocating Piston compressors are the most widely used air compressors compared to other positive displacement compressors. They have been further divided into single-acting and double acting.
- Single Acting: In single-acting reciprocating air compressors, the air is drawn and compressed only on one side of the air compressor while the other side gets in touch with the crankcase of the air compressor. In such cases, the downward stroke of the piston draws the air, and the upward stroke compresses it. Such air compressors usually operate on 25 HP or below and are primarily used in small businesses, DIY projects, hobbyists, and even small industries.
- Double Acting: On the other hand, double chambers are present on both sides in double-acting reciprocating air compressors. In such air compressors, the air is drawn at the top and compressed at the bottom on the downstroke, and on the upstroke, the air is drawn towards the bottom side and is compressed on the top side. The Horsepower of these air compressors can fall somewhere between 40-1000.
2. Rotary Screw Compressors
The usage of rotary screw compressors has increased significantly in various industries, and the size can vary from 25 to 300 Horsepower. These air compressors operate by drawing the air and lubricant into a void created by the two helical rotors meshing together. As the rotors pass by the pump’s inlet port, the cavity for the remainder of the rotation decreases significantly, which makes the air-oil mixture compress. Modern-day rotary screw compressors come with air coolers, motor controls, and in-built safety devices.
3. Rotary Vane Compressors
Rotary sliding vane compressors work somewhat like an air motor, rotating sliding vanes with an off-center rotor. The air compressors, as the vanes, approach the region where the gap between the rotor and casing is narrow. Rotary vane compressors and rotary screw compressors are pretty similar to each other. They require the same separators and oil system parts as oil-injected machines. Usually, larger separators result in more oil carryover on vane compressors than on comparable piston compressors.
4. Oil-free Compressors
Most positive displacement compressor types are available in oil-free or oil-less designs, preventing air from being injected with lubricant. Oil-free refers to systems with a lubricated crankcase isolated from the compression chamber. In contrast, oil-less often refers to machines containing absolutely no oil. Generally, oil-free and oil-less machines are less efficient and require more maintenance than their lubricated substitutes by 10% to 20%.
Conclusion
We hope this article helped our readers differentiate between different types of positive displacement compressors. Do not forget to check our website for informational content regarding air compressors.
