Industrial Utility Efficiency

# Correctly Solving Low Air Pressure Problems

“For every complex problem there is a solution that is simple, neat and wrong.”

HL Mencken uttered those words over a century ago and they’re still just as true today as they were then. One of the most common problems in plants is low air pressure. One of the most common solutions is to purchase new air compressors. Often this advice leads to a poor return on investment with the company’s hard-earned money. Often the issues are related to demand, distribution, or both. Solving the wrong problem can be expensive from a capital and operating cost perspective. Determining root cause analysis may cost more up front, but will save tens if not hundreds of thousands of dollars long term.

### When Compressed Air Distribution is the Main Culprit

Pressure problems were the reason our very first customer ever called us. This cement plant had an issue where lower air pressure intermittently affected the operation causing a rework issue on an irregular basis. When low air pressure occurred in the silos, where trucks were loading, one of the valves responsible for feeding the cement into the truck did not have enough pressure behind it to close. When this happened, the operator had to run up a flight of stairs and manually close the valve. In the meantime, the contents in the silo would continue to spill out on top of the truck.

### Cement Import Terminal Productivity Problems

A cement import terminal had all the usual productivity problems one develops with moisture in the air such as sticky valves, small boulder formation in the silos, blinding in the baghouses, etc.

Their sister cement plant had recently hired Compressed Air Consultants (CAC) to audit their system and were pleased with the results. The terminal called CAC to talk about their problems. In the ensuing discussions, it was discovered the plant used to run solely on a 75 hp and the 125 hp was only used when the plant was blending cement for the bagging operations.

The plant had three basic modes of operation: Standard operation (ship unloading and truck loading), bagging operations, and shut down. The plant had two primary problems. The first was an air pressure problem at the top of the load-out silo while moisture was a problem throughout the facility.

The plant originally ran on a 75 hp air compressor by itself with a 125 hp machine operating only during the bagging operation to feed the blenders and dense phase transporters. This only occurred less than 5% of the week. Over time, the plant found it couldn’t run on just the 75 hp and had to run both compressors, yet there weren’t any new applications in the plant.

### Conclusion

Far too often, compressed air pressure issues are assumed to be supply side related. While adding new compressors may solve the problem, it can often mask the root cause driving operating costs up while spending unnecessary capital. In some cases, the capital expenditure doesn’t solve the problem leaving the plant back at square one. If you have low air pressure issues, make sure you examine supply, distribution and demand to determine the root cause.

For more information, contact Paul Edwards, tel: (704) 376-2600, email: paul.edwards@loweraircost.com, or visit www.lowercostair.com/web.