This article explains how to calculate compressed air consumption at different inlet pressures. Two air nozzles from our range serve as real-world examples.
-
- V1,V2 in l/min are to be read as standard litres/normal litres per minute (SLPM)
- P1,P2 are to be read as gauge pressure (not absolute pressure)
EXAMPLE 1: Compressed air consumption depends on air pressure
We determine the consumption of a Super Air Knife with a length of 1″ (=25.4 mm) and a 0.05 mm thick shim (factory-fitted) at various pressures.
Base value: at 5.5 bar (=P1), consumption is 82 l/min (=V1).
Calculation formula: V2= (V1 x (P2+1)) / (P1+1), where 1 stands for atmospheric pressure of 1 bar and P2>1 bar.
| P2 | – V2 | |
| 1.4 bar | – 31 l/min | |
| 2.8 bar | – 48 l/min | |
| 4.1 bar | – 65 l/min | |
| 5.5 bar | – 82 l/min | |
| 6.9 bar | – 99 l/min |
The total air consumption for any air knife is then very easy to work out: simply multiply the length (in inches) by the relevant air consumption above (in l/min).
EXAMPLE 2: Air consumption is directly proportional to the actual inlet pressure
- SLPM = standard litres per minute
- 1 bar = atmospheric pressure
| SLPM2 | = | P2 + 1 bar |
| SLPM1 | = | P1 + 1 bar |
A model 3215 vortex tube consumes 425 SLPM at 6.9 bar.
To calculate the air flow at an inlet pressure of 5.5 bar as a worked example, proceed as follows:
| SLPM2 | 5.5 bar + 1.0135 | |
|
|
= |
|
| 425 | 6.9 bar + 1.0135 | |
| SLPM2 | 6.5 | |
|
|
= |
|
| 425 | 7.9 |
| SLPM2 | = | 350 |
Result: the model 3215, which consumes 425 SLPM at 6.9 bar, consumes 350 SLPM at 5.5 bar.
Do you have any questions? We are here for you!
Simply contact our experts: Technical advice from EPUTEC Drucklufttechnik