SYSTEM DESIGN. OPTIMAL COMPRESSED AIR SYSTEMS BY HARINGA

A GUIDE FOR DESIGNING SYSTEM PIPING

Compressor room piping, between compressor(s), filters, dryers and receiver, should be sized for the maximum flow rate of the compressor(s) and have less than a 1 PSIG pressure drop.

Enter the compressor room air receiver at the lower opening and exit from the upper opening. In California, all piping in or out of an air receiver must be metallic, schedule 80, to the first shut off valve.

Header piping from the receiver should be sloped in the direction of the flow, one inch per ten feet being the minimum pitch to carry condensate to sumps and separators from removal. Note that sloping, sumps, separators, etc, are not required when an effective air drying system is installed.

Header piping from the receiver should be sized for the maximum installed and anticipated compressor capacity for the system, up to the first “T” intersection, in a “loop” system, or the first “branch line” in a “single header system”, and have less than a 1 PSIG drop. After either of these two points, the header pipe size can be reduced to the maximum anticipated flow, and have less than a 1 PSIG drop. The entire header system pressure drop from one end to the other should not exceed 1 to 1.5 PSIG. Note that the extra installed cost of the next larger pipe size is not much greater than that of the minimum size that could be used. Installing larger pipe initially will significantly lower the cost of future compressor capacity add-ons.

Branch piping should be sized for the maximum flow and have less than a 1 PSIG pressure drop from the header. How many tools or devices will be operating at one time off a branch line determines the maximum flow rate. Feed lines off branch piping should be sized using the same criteria as that for the branch piping.

Point of Use hoses, air line filters, regulators, lubricators and quick disconnects should be sized according to flow rates so that “total” pressure drop through them does not exceed 7 PSIG with tools and devices operating at full power. Note that hoses should be no longer than necessary to give operators sufficient freedom of movement. Where long hose runs are necessary, use a large hose plus a shorter lighter “whip” hose at the tool.

Other Piping Tips:

  • Install automatic drains to insure drainage. No Air Loss type is preferred.
  • Schedule 40 black iron and copper pipe are the most widely used for compressed air.
  • Some plastic and aluminum piping are now acceptable by OSHA. Its use is intended for the “demand side” of systems.
  • Use long radius bends wherever possible.
  • Use welded joints for iron pipe  Wherever possible to reduce leakage and eliminate fittings.
  • Incorporate strainers and lubricators for all tools in the piping.
  • Never use fittings on a tool that are smaller than the tool itself.
  • Install a shut off valve in front of each hose, and make provisions for keeping the hoses off the floor.

Maintaining the Piping System

  • Perform leak surveys on a regular basis. It takes 25 HP to feed leaks equivalent to a ¼” orifice.
  • Make random air pressure checks at various tools, when they are operating.
  • Check, repair or replace automatic drains at regular intervals. Their malfunction causes serious system contamination.
  • Repair or scrap damaged hoses and fittings.
  • Keep strainers empty and lubricators filled.
  • When adding new tools or devices, check all air lines for the ability to carry the additional load.

 

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