Understanding Air Compressors – Part 3

Bits and Pieces: Fluid Power Fact #4/3

Understanding Air Compressors – Part 3

 [Note: Part 1 of this article presents basics of air compressors. Part 2 presents the classification and the construction details of air compressors. Part 3 presents a brief about the sizing of air compressors.]

Sizing Air Compressors

Sizing an air compressor for an application requires a logical sequence of actions. The following steps highlight a systematic approach for selecting the right air compressor.

1. Determine the air requirements of the application. Use the chart published by manufacturers to determine the average flow rate requirements [(lpm (FAD) or cfm (FAD)] of every air consuming device.

2. Once the air requirement of each of the air consuming devices has been determined, calculate the total air requirement of all the air consuming devices, allowing for leaks and future expansion.

3. Find the duty cycle of the application.  It is an attempt to find the number of hours the compressor is expected to run. For example, if 70% of the time the compressor is expected to provide air to the equipment, the amount of air to be supplied by the compressor would be 0.7 x the total air requirement as calculated in step 2.

4. Determine the required pressure (psig). Most actuators and air tools require 6 to 7 bar [90 to 100 psi]. Many other actuators and tools may require up to 10 bar [150 psi].

5. Check for the voltage and phase where the compressor is going to be located. This is a critical step in sizing and selecting the proper compressor.

6. Determine the compressor tank (receiver) size. Most manufacturers offer standard sizes based on the delivery of the compressor.

A Sample Air Consumption Chart for Automotive Service Shops


Consumption cfm (FAD)

Consumption lpm (FAD) Max. Pressure (psi) Max. Pressure (bar)
Blow Gun





Impact Wrench 1/2″





Paint Spray Gun





Car Lift

6 170 175 12


Bangalore, India

07338385505 | 080-29729505

Email: info@fluidsys.org

Website: https://fluidsys.org

 Comprehensive Training offered in Pneumatics and Hydraulics!!

Fluid power technology is fascinating as ever!! It may take many more years to have a uniform approach towards evolving product lines so that manufacturers and end-users have a common ground.

Fluidsys Training Centre, Bangalore is striving to meet the challenge with a systematic training in the field of Pneumatics and Hydraulics.

Fluidsys Training Centre, Bangalore will be conducting a six-week long-term training program on ‘Professional in Pneumatics and Hydraulics – Advanced level with TUV Rheinland Certified Qualification’* from this academic year (2018-19) onwards, apart from the regular short duration (3 to 4 days) courses.

Please contact the Training Centre for more details…

[*Approval from TUV Rheinland is awaited].


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