Thread: Compressor query

I think you will get an obvious answer from a number of more knowledgable people than me: a 12CFM air compressor will need around 2.5 to 3Hp. That means you will need 5 - 6Hp to run your combined 22-23CFM compressor setup.... 100l combined tank is also too small for even one 12CFM pump. Try to go for about 120l per 12CFM to give the motor and pump a rest between restarts. You could use one of the 50l tanks as a secondary tank to reduce the humidity of the air and have your regulator on that one.

Using a higher RMP motor makes no difference as 3HP is 3HP at any RMP.
12 CFM is a theoretical maximum that a 3HP motor can generate but in practice it will be lower than this.

Even if you could find a higher revving motor, Most compressor pumps also do not like being spun at speeds above their rating. The increased RPMs rapidly generates higher temperatures leading to increased wear and tear.

Most compressor CFM ratings are exaggerated by Manufacturers.

The way to measure the air delivery rate under pressure is as follows
T) Time the recharge time in minutes (lets say it takes 1 minute)
P) Look at the pressure gauge as soon as the recharge starts and then when it stops, lets say it turns on at 85PSI and turns itself of at 120PSI (total increase of pressure = 45 PSI) and divide that by 15 to get atmospheres so in this case its 45/15 = 3
C) Convert the tank size into Cubic ft (divide the Litres by 28) lets say its a 56 L tank so that is 2 cubic ft

The air delivery rate is then (P x C)/T or in my example its 3 x 2/1 = 6 CFM
To be a 12 CFM compressor the recharge time for this compressor would have to be 30 seconds!

Don't be very surprised if your CFM is round half what the manufacturer says it is.