75.CALCULATING THE STORED COMPRESSED AIR IN A RECEIVER TANK

In any good compressed air system there is a receiver which stores compressed air. One of the advantages of compressed air is that it is an “on demand” source of energy. When it is not needed, it can be immediately turned off. When needed, immediately turned on. Energy is stored in a tank.

This is a particular advantage in intermittent applications, whether it is for the demand of a pneumatic tool or machine or for blow off applications. By storing compressed air, you can utilize a smaller compressor and use less overall energy with adequate storage capacity.

The receiver volume may be calculated using the formula

t = V (P1- P2) / (SCFM) PA

where

V = volume of the receiver tank (cu ft)

t = time in minutes for the receiver to go from upper to lower pressure limits

SCFM = air flow (SCFM)

PA = atmospheric pressure (14.7 PSIA)

P1 = maximum tank pressure (PSIA)

P2 = minimum tank pressure (PSIA)

There are recommended tank sizes based on consumption demand. The demand should be “average” demand taking into account intermittent use. Much is made of the high energy cost of compressed air. But the fact that it can be stored and used “on demand” does offer advantages especially in intermittent applications such as blow off in packaging or part ejection applications where the air does not have be constantly on thereby reducing energy use significantly, in some cases even approaching the cost of electrically operated blowers without the additional maintenance costs, noise and added footprint they create.