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List the factors to be considered for selecting the pipes while designing the pneumatic system.

Factors to be considered while selecting the pipe for pneumatic system

1. Pressure of compressed air in the line.
2. Total flow rate per unit time through the line.
3. Permissible pressure drop in the line.
4. Type of tube material and type of line fittings.
5. Length and diameter of tube or other pipelines.
6. Working environment.

Pipe Size Specifications: Generally pipe size is specified in three ways

1. Nominal Pipe Size (NPS) : This number indicates the base diameter of pipe in inches. e.g. : ½ inch, ¾ inch, 1 inch, 1 ½ inch etc.

2. Schedule Number (SCH): This number is based on wall thickness, greater the SCH, greater will be the wall thickness of pipe. A schedule number indicates the approximate value of

   SCH = 1000 * P / S where P – service pressure & S – Allowable stress

   SCH Number 40, 80 and 160 are widely used.

3. Pipes are also classified as Standard (STD), Extra strong (XS) size, Double Extra strong (XXS) size based on strength.