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Posts Tagged ‘Rotary Screw Air Compressors’

Air compressor units are used for a variety of jobs ranging from filling up tires to running complex industrial applications. Due to the wide variety of requirements and units available, they have been primarily divided into three types according to the way they operate to compress air to the desired pressure. Also some of these are Gas Powered air compressors and some are electric.

A. Reciprocating Air Compressors – These are basically positive displacement machines and reduce the volume of air to increase its pressure. A piston is used to increase the pressure of air in an enclosed space. Then another batch of air is taken in and the piston is used to increase the pressure of the total volume. This step is repeated till the desired pressure is attained. Commercially the compressors available are either single stage or two stage units. Single stage units are used to get air to a pressure of 70 to 100 pounds per square inch and two stage units are used to generate a pressure in the range of 100 to 250 pounds per square inch. Further, these compressors are single acting when they use only one side of the piston and double acting when they use both the sides. These are further sub divided into air cooled or water cooled units and oil lubricated and oil free units.

B. Rotary Screw Air Compressors – These use the two rotors inside a caging to compress the air to the desired pressure range. These are usually cooled by oil and use either water cooled or air cooled oil coolers thereby reducing high temperatures inside the unit. They do not have any valves making them easy to operate and maintain. Running them on variable speed and variable displacement alters the capacity while maintaining a smooth air outflow. During operation, oil is kept in a separate chamber so as to eliminate any contamination due to oil. Oil free options are also available.

C. Centrifugal Compressors – These use a rotating impeller to transfer energy to air making it a dynamic machine. The momentum created by the impeller is converted into a high pressure discharge that helps increase the pressure of air within the unit. As the flow is continuous and reliable, these units are used for higher capacities and extended usage. The units are always oil free and the running gear though lubricated with oil is in a separate sealed chamber.

These are just the basic divisions of the types of Air Compressors available and each type can be further subdivided according to the number of compression stages, the cooling method used, the drive method used, the way lubrication is done and whether it comes as a package or is custom built as per the specifications given. These divisions and sub divisions help the customers to select the unit that matches their requirement as much as possible.