Determine the correct size piping
Three factors are important in determining the correct size piping system for your plant.
- A) Total current and estimated total usage.We need to establish what volume of air is required by your plant. A good starting point is to find out the delivery volume for the air compressor in litres per second or cfm and the required operating pressure of the system.
- B) Distance to points of major air demand.Establish air supply requirements for each area of the installation and map these out on a site plan. Airquip Piping can assist to calculate friction losses.
- C) Future expansion and growth in air demand. If a plant is to be constructed in stages it is wise to keep in mind the whole installation at design stage. As a rule of thumb, we recommend compressed air main sizing is based on a minimum of 30% higher than the maximum compressor delivery volume. This allows for some storage in case of unforeseen expansion.
Once the maximum air volumes have been established and the recommended safety margin has been added, use the table below to determine the correct size pipework.
| Max Flow Rate at 7 bar | Recommended Pipe Size | |
| Litres/Second | Cubic feet/minute | Internal Diameter (I.D.) |
| 15 | 31 | 12mm |
| 28.5 | 60 | 17.5mm |
| 35 | 74 | 18mm |
| 57 | 120 | 23mm |
| 135 | 286 | 29mm |
| 175 | 370 | 36mm |
| 340 | 720 | 45.8mm |
| 440 | 932 | 51mm |
| 690 | 1462 | 65mm |
| 950 | 2012 | 72mm |
| 1250 | 2648 | 80mm |
| 3000 | 6356 | 104mm |
| 3500 | 7416 | 114mm |
These flow values are intended as a guide only.
Actual flow rates will be determined by a variety of factors including the number of bends, supply pressure and variations in friction loss relative to each material.
- *For higher pressure applications, flow rate capabilities can be increased. Call our technical department for details.
- *Flow values allow for a pressure drop of 4% over 30 metres of pipe. If a maximum pressure drop of 2% is required, these flow values should be reduced by 20 – 30%.
Note: A.N.R. (Atmosphire Normale de Reference) Standard Reference Atmosphere ISO R554 : 20°C, 65% Relative Humidity 1013 mbar