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Comparison of screw machine and piston machine

November 01, 2021

The history of the air compressor can be updated to 1800. With the time goes by, many types of air compressor has born. Air compressors can be applied in many fields, including steel, electric power, metallurgy, shipbuilding, electronics, textiles, mining, chemicals, petroleum, light industry, food and medicine, transportation facilities, casting and spraying and other fields. Today, we will focus on the differences between Screw Air Compressor and Piston Air Compressor.

 

1. Application scope

The screw air compressors are used in normal field. Not suitable for small capacity and high pressure occasions. On the contrary, piston air compressors are used widely. It has the unique cost advantage in micro field, and it is the only choice in ultra high pressure field.

 

2. The balance of force

The balance force of the screw air compressors are good. There is no unbalanced inertial forces. Although there is an unbalanced air force, it has little influence on the smoothness of operation. The piston air compressor is bad. As the crankshaft rotates, the piston speed changes greatly, resulting in a large inertial force.

 

3. Vibration and noise

For screw air compressor, the vibration and noise is very small, no foundation required. The vibration and noise of piston air compressor is large, and it generally requires foundation except for microcomputers.

 

4. Efficiency and energy consumption

Screw air compressor can reduce 15%-25% energy consumption with high efficiency. Piston air compressor has many friction pairs, low speed, low efficiency, high energy consumption.

 

5. Air end structure

The former is simple, while the piston air compressor is complex.

 

6. Volume and Weight

Screw air compressor is in small size and with high speed . It is light weight and saves the row material.

Piston air compressor is heavy and in large volume with low speed.

 

7. Driving Method

Screw air compressor are small size machines, and they are mostly driven by belts, medium and large machines are mostly directly connected to motors, and speed gears are added when the speed is high.

Most of piston air compressors are belt drive, the bearing is subjected to large radial force, and the crankshaft is subjected to large bending moment, which is easy to cause failures.

 

8. Appearance

Screw air compressors are generally in box type with the feature of good integrity, small footprint, neat and beautiful appearance. For piston air compressors, generally, there is no outer cover, and the structure of the whole machine is loose, so the occupied area is large. There is oil mist coming out of the breathing valve, and the body is easy to accumulate oil. It is not that beautiful.

 

9. Reliability and life span

The reliability of the screw air compressors is high, and the life span is long. The rotor of the air end is not worn, and the life is limited by the life of the bearing only, which can generally reach more than 60,000 hours. After the bearing is replaced, it is the same as the new machine.

 

Many friction pairs and large mechanical loss for piston air compressors. The load changes greatly, and the failure rate is high.Service life is short. The life of wearing parts such as valves and piston rings is only thousands of hours. Because all the moving parts cannot be replaced, the old machine cannot be repaired as new one.

 

10. Compressed air quality

For screw air compressor, the exhaust temperature is low. The oil and gas are separated and filtered before it is exhausted, and the oil content and impurity content are low. Moreover, the airflow pulsation is small, and it can be equipped with a smaller air storage tank, or even sometimes does not need to be equipped with an air storage tank, and the compressed air quality is good.

 

For piston air compressors, the exhaust temperature is high. Generally, there is no oil and gas separator installed on the unit, and the oil content and impurity content are high. Moreover, the airflow pulsation is large, so it must be equipped with large air storage tank. The compressed air quality is bad.

 

11. Influence on the environment

The influence on the environment of the screw air compressor is less. Except for the discharge of condensate, there is no other discharge, and saving energy and row material and long life span are also a kind of protection for the environment.

 

For piston air compressor, besides the discharge of condensate, there is also oil mist from the breathing valve that pollutes the environment.

 

 

12. Durability

Main moving parts of screw air compressor have no direct friction; And it has stable output; Air capacity does not decrease over time; The working condition of the old machine is the same as the new machine.

 

For the piston air compressor, after a period of use, due to the wear of the moving parts, the working conditions become worse, and the air capacity reduces, the fuel consumption increases, and the vibration and noise become larger.

 

In conclusion, piston air compressors have many wearing parts and poor reliability. Screw air compressors have simple structure, small size, no wearing parts, reliable work, long life, simple maintenance, low noise, energy saving, good repairability, and can be used It has large selectivity and is widely used, so screw air compressor is better.


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