Blowers & Compressors Understanding Blowers: How to Make the Best Use of Blowers and Compressors

| Author / Editor: Courteously of PROCESS India / Dominik Stephan

Right application of blowers and compressors is very essential for the most optimised performance. A good system layout offers more power saving and higher efficiency. It is also important to make sure that proper care is taken during piping design and installation.

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Low pressure compressor
Low pressure compressor
(Picture: Wikimedia Commons)

Compressors and fans are essentially pumps for gases. Although they differ in construction from liquid handling machines, the principles of operations are similar. Gases being compressible, a large portion of the energy of compression is dissipated in form of heat to the gas. This limits the operation of the compressor unless suitable cooling is effected. Various gas machines can be classified depending upon their compression ratio i.e., ratio of final pressure P2 to suction pressure P1.

Centrifugal Blowers and Fans

This range covers various types of centrifugal and axial flow fans, which have relatively high air displacement but low compression ratios. They are either of centrifugal types, axial flow types or regenerative types.


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As their internal clearances are relatively high, the discharge pressures are limited to few inches of water only. These types are generally used for applications requiring high volumes but low pressures – such as in air-conditioning, in furnaces, low pressure cooling, dust or fume extraction systems, lean phase pneumatic conveying etc.

Positive Displacement Blowers (Roots Blowers)

Twin lobes and three lobes type blowers fall under this category. They have higher efficiency at moderate compression ratios, and are most efficient in the compression ratios of 1.1 to 2. They find use in applications, which require relatively constant flow rate at varying discharge pressures. These are generally available for capacities 10m3/hr to 10,000m3/hr for pressures up to 1kg/cm2(g) in single stage construction.

They are extensively used in applications such as pneumatic conveying, aeration in ETP, cement plants, water treatment plants for filter backwash, aquaculture, aeration etc.

Compressors – For Highest Compression Ratios

Reciprocating, vane or screw type compressors are the machines in which compression ratios are high, generally more than 2.5. These are generally required for applications requiring low airflow, but high pressures such as pneumatic tools, solenoid valves, paint shops, drilling rigs etc.

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