A positive displacement air compressor refers to a type of air compressor that works by inhaling a specific volume of gas or air and increasing the gas pressure by reducing the volume of a closed cylinder. There are mainly piston air compressors and screw air compressors. Among them, screw air compressors are divided into single-screw air compressors and twin-screw air compressors. This article will take an in-depth look at two typical positive displacement air compressors, piston air compressor and screw air compressor.
- Piston air compressor
Piston air compressor is the earliest developed and common type of compressor in industrial compressors. Its structure can be single-acting or double-acting, or oil-lubricated or oil-free, and the number of cylinders in each structure is also different. Piston compressors come in various forms, including upright cylinder small compressors and the common V-shaped small compressor.
The piston compressor has a valve system composed of two sets of stainless steel valve plates. When the piston moves upward, the large valve plate folds and rises, sealing the valve seat, and then the expansion and contraction of the small valve plate forces the compressed air through the hole in the valve seat.
- Single screw air compressor
The main engine of a single-screw air compressor is mainly composed of a screw and two symmetrically arranged star wheels. When the motor drives the screw to rotate, the screw also drives the intermeshing star wheels to rotate, thereby compressing the air in it. Single screw air compressor is a type of air compressor that is widely used on the market.
3.Twin screw compressor
The development of twin-screw compressors can be traced back to the 1930s, when there was a need for a rotary compressor with high flow rates and stable flow under pressure changes.
The main parts of the twin-screw element are the convex rotor and the concave rotor. When they rotate in opposite directions, the volume between them and the shell decreases. Each screw has a fixed, built-in compression ratio that depends on the length of the screw, the pitch of the screw, and the shape of the exhaust passage. To achieve maximum efficiency, the built-in compression ratio must be adapted to the required operating pressure.
A characteristic of the screw air compressor is that there is no mechanical force that causes imbalance. That is to say, the screw air compressor can handle gas with a larger flow rate at a higher shaft speed and a smaller volume. This characteristic allows the screw to Air compressors are more adaptable to today’s industrial development, and screw air compressors have become the more commonly used air compressors on the market.
