An auditor recently received a call about low pressure from a client operating a printing plant. The main presses were having production issues and the plant pressure needed to be increased to compensate. Because the client had received a financial incentive for lowering his pressure, the power company was breathing down his neck to return the pressure to the original value or return the money.
The auditor dutifully went to investigate and placed data loggers at strategic points along the plant distribution network. The instruments indeed found excessive pressure differential, showing the presses were being starved for air. What was strange was that the presses were located only 20-ft away from the compressor room and had adequately sized distribution piping. The piping drops to the press were well sized for peak flows and so too were the filter/regulator/lubricators within the press. After very careful investigation there appeared to be no reason for the pressure differential, and yet there it was.
The auditor was stumped. He walked up and down the distribution system scratching his head and looking for the cause, until a slightly sheepish looking maintenance working tapped him on the shoulder. The worker had been involved in installing the distribution piping years ago and had installed two isolation ball valves at the source inside the compressor room. It turned out that the ball valve were installed too close together so the handles touched, meaning they both could not be fully opened at the same time. To fix the problem, he modified one of the handles so that when it was open the handle was at 90°, solving the problem. In the years that passed, he forgot about the valve and one day one of his co-workers “opened” what he thought was a closed valve. Because the valve was actually closed, instead of sending air directly to the presses, the air had to travel to the far end of the plant and back to feed the presses. He has suddenly remembered his modification and sure enough that was the problem.
Returning the valve to its open position solved the problem. The valve was quickly corrected by properly installing the valve with the correct handle. Problem solved!
Learn more about measuring pressure differential in the Compressed Air Challenge webinar scheduled for November 2013.
By Ron Marshall for the Compressed Air Challenge
Filed Under: Pneumatic Tips