Compressed air gone wrong: Super pressure control is wasted

Posted by Paul Heney+ on Tuesday, July 9, 2013 ·

compressed air 5A recent compressed air audit revealed superior compressed air pressure control at a local fiberglass products manufacturer that had installed a VSD compressor in their plant several years ago. The discharge pressure at the compressor was very nicely maintained at a precise 125 psi by the compressor’s ability use electronic control to speed up or slow down. This excellent control comes at a premium, as the VSD compressors cost more than standard units.

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More Than Seals & Cylinders.................Solutions!

More Than Seals & Cylinders……………..Solutions!

But something was wrong.

The plant was having trouble maintaining consistent output from its compressed air powered tools. During production shifts in the middle of the day, the tools would slow and lose power—this was affecting production. An audit was done to determine why this was happening.

Data loggers were installed at critical plant locations to determine if there was any pressure differential in the compressor air piping or other components in the system. The readings showed that despite the accurate compressor control, the pressure in the plant sagged to as low as 80 psi, an amazing 45 psi lower than the pressure set point of the VSD compressor! On top of this, the pressure at the 90 psi rated tool dropped to 40 psi when the tool was operating. The result was very low tool power.

The cause? An undersized air cooler had been installed to remove excess heat before the air dryer in the poorly ventilated compressor room. Additionally, a pressure/flow controller had failed, causing a high pressure differential across it rather than a constant regulated pressure. The hoses and connectors feeding the tools were undersized for the flow demanded and the hoses were too long, being part of 50 foot long hose reel assemblies.

Significant money had been spent to assure well-controlled pressure at the compressor discharge, but the benefits were not being received, due to poor attention to downstream components.

The actual pressure required in the plant is only 100 psi. By modifying and repairing the offending components, and by installing remote sensing on the air compressor, a constant 100 psi plant pressure can be achieved with average compressor discharge pressures falling to about 105 psi. Tool pressure can be improved by shortening hose lengths, increasing hose diameter and eliminating redundant quick connect couplers. This compressor pressure reduction saves 10% on energy. And the improvement in pressure differential solves the air tool productivity problems.

The next project is the sister plant across the street. Preliminary measurements there show pressure sags are even worse!

Learn more about measuring pressure differential at the Compressed Air Challenge webinar scheduled for November, 2013. Click here for more information and to register.

By Ron Marshall for the Compressed Air Challenge www.compressedairchallenge.org