What are the advantages of screw air compressors over piston compressors?

The choice of screw and piston air compressors requires consideration from all aspects in order to select the right one for you, and we compare the following in terms of function and performance. 

1. Comparison of screw air compressor and piston air compressor in terms of function

(1). Force balance
Single-screw compressor: the radial and axial gas forces borne by the screw can be automatically balanced, and the star wheel teeth bear the gas forces, requiring the star wheel teeth to have sufficient strength and rigidity. Twin-screw compressor: the screw rotor to withstand the larger radial and axial gas forces, the requirements of the screw has sufficient strength and rigidity.

(2). Manufacturing costs
Single-screw compressor: screw and star wheel bearings can be used for ordinary bearings, manufacturing costs are low. Twin-screw compressor: due to the two screw rotor load is relatively large, requiring the use of higher precision bearings, manufacturing costs are higher.

(3). Reliability and operating costs
Single-screw compressor: single-screw compressor star wheel is a perishable part, in addition to the star wheel material has high requirements, the star wheel also needs to be replaced regularly, the operating costs are high. Twin-screw compressor: twin-screw compressor without wearing parts, trouble-free operation time can reach 40,000 to 80,000 hours, the operating costs are low.

(4).  Efficiency
In the new state, single-screw compressor and twin-screw compressor efficiency is basically the same. With the increase in operating time, the single screw compressor star wheel wear will lead to a reduction in air volume and efficiency.

(5). Noise and vibration aspects
Single screw compressor and twin screw compressor noise and vibration are basically the same.

(6). Processing equipment Single screw compressor: there is no mature special processing equipment, which in turn leads to the product performance is not very stable. Twin-screw compressors: there is a mature screw special milling and grinding machines to ensure stable product performance.

(7). Operation and maintenance aspects
The daily operation and maintenance of single screw compressors and twin screw compressors are basically the same.

(8). Applicability
Single screw compressor: suitable for high discharge pressure occasions, such as high-pressure air compressors, refrigeration compressors and natural gas compressors. Due to the rotor stiffness and bearing load and other restrictions, twin-screw compressors can only be used in the low-pressure range, such as power air compressors, refrigeration compressors and low-pressure natural gas compressors, etc., the exhaust pressure generally can not exceed 4.5MPa.

2. Comparison of screw air compressor and piston air compressor in terms of performance

(1). Technically
Single-screw air compressor is not twin-screw mature, there is no relevant industry standards and national standards, the machine failure to explain the right to the air compressor manufacturer, China's twin-screw air compressor must comply with national standards and industry standards GB8542, TB/T6430. Single-screw air compressor through a single screw and two star wheel mesh compressed air, the three direct contact, resulting in more serious friction between the star wheel and the rotor. (The material of the single-screw star wheel is resin material so it is easy to wear when the star wheel and the screw are engaged in operation, and the resin foam is easily mixed into the oil of the main engine, resulting in high compressor temperature and downtime.) The use time is not long, and the internal leakage of the head is large and the exhaust volume is reduced. Twin-screw through the Yang and Yin rotor mesh, there is an oil film between the two rotors without direct contact, friction is small, the exhaust volume does not change with time.

(2). Motor
The main motor of the single-screw air compressor is an ordinary motor, and the main motor of the twin-screw is an energy-saving motor, so the single-screw motor bearing wear is serious, increasing the operating costs. At present, the international first-class brands of air compressors, are made of twin-screw air compressors, such as Sweden's Atlas, Japan's Shen Steel, the United States Ingersoll-Rand, etc. have not used single-screw air compressors.

(3). Maintenance costs 
Single-screw air compressor although the purchase cost is relatively low, the star wheel and rotor friction between the more serious, the need to change the star wheel, maintenance costs, operating costs will naturally be high, or exhaust volume back to the loss of serious failure to meet the specified requirements. Twin-screw air compressor temporary purchase cost although the problem is on the high side, but there is a very high mechanical reliability, smooth operation, applicability, so that the later maintenance costs are very low, the failure rate is low, and will not affect production.
Analysis of the advantages and disadvantages of screw and piston air compressors as one of the core tasks of engineering management. It has a very important role to play in the management of engineering projects. We must adopt a scientific approach for use in the analysis.

Now that you know the difference in function and performance between screw and piston air compressors, if you want to know more about the application of air compressors, you can read our article "Comprehensive Application of Air Compressors".