Introduction to Industrial Automation

5.4   Distribution of Pressurized Air

Every pneumatic automation setup is supplied by pressurized air from a pressurized container of 

the compressor, commonly known as a compression tank, through the distribution pipes. The 

diameter of this pipe should be such that the pressure drops among the compressor and the pneu-

matic installation should be less than 0.1 bar. A bigger pressure drop creates a problem in the 

operation of the pneumatic automation, a situation that is equivalent to the drop of the electrical 

voltage. The pipes carrying the pressurized air can be made out of copper, steel, or plastic.

The selection of the pipe’s diameter is made based on the utilization of two nomograms. The 

parameters that are inserted in these calculations are as follows:

  1. The volumetric flow of the pressurized air

  2. The length of the pipe

  3. The operational pressure of the pressurized air

  4. The allowable drop of pressure

Additionally, the diameter of the distribution pipes is affected by the number and the type of 

various equipment that are placed in the pneumatic installation, such as the pneumatic two-way 

valves, the regulator valves, the pneumatic T-connectors (or curve connectors), the pneumatic 

switches, etc. This equipment is utilized in the calculations through their “equivalent length”. 

This equivalence refers to their resistance during the flowing of the pressurized air, while the 

“equivalent length” expresses the length of the pipe of the same diameter that is characterized by 

the same resistance to the equipment. The way of calculating the diameter of the pipe is presented 

subsequently by the utilization of an example, which it should be noted is the same procedure for 

all different types of materials.