Knowing the velocity of compressed air delivered by a compressor allows you to select the correct machine to suit your air-driven tools, such as impact drills, staplers and spray-guns. Although there are a number of websites incorporating online compressed air calculators, using the compressed air velocity formula during your shopping expedition can help you arrive at an early decision without going online.

- Skill level:
- Easy

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## Instructions

- 1
Using the following figures as an example: a) Compressor input flow rate = 750 cubic meters of ambient air per hour at 1 bar. b) Internal diameter of compressed air pipe (D) = 60mm. c) Compressed air flow rate (Q) = 75 cubic meters per hour at 7 bar; Calculate the velocity of compressed air (v) in the pipeline as follows:

- 2
Rounding off the value of pi to 3.142, the formula for the velocity of compressed air (v) equals the compressed air flow rate (Q) divided by a quarter of the cross sectional area of the compressed air pipe (A). Therefore 75 cubic meters/hour divided by (0.25 x 3.142 x 0.060 squared) = Velocity of 26,552 cubic meters per hour.

- 3
Calculate the per-second velocity as follows: Divide the per-hour velocity by the number of seconds in an hour. Therefore in the above example, 26,552/3600 = 7.4 cubic meters per second velocity.