By Ron Marshall
An automotive parts manufacturer had expanded their production and were running out of compressed air capacity. The pressure was dropping so low that it was interrupting production activities and causing parts delays. Facing these problems, the maintenance foreman rented a small diesel compressor to supplement his other three electric compressors, putting it right outside of one of his compressor rooms.
This solved the problem, for a while. After a couple of weeks, the manager started receiving more low pressure complaints, and started to hear about air quality problems where moisture was found in the compressed air system.
An investigation revealed that the brand new inlet filter in one of the compressors — the one closest to the portable unit — had plugged up so badly that the flexible rubber intake on the compressor screw element intake had collapsed. The compressor was running, but making no air. The cause was found to be diesel fumes being ingested because the portable compressor had been located right at the intake to the plant.
The air quality problem was found to be excessive compressed air discharge temperature. The portable compressor has no compressed air aftercooler, making the compressor discharge very hot. The dryer for the electric compressor is therefore undersized due to this excess heat and one extra compressor. Also, the exhaust ducting of the electric compressor was blowing hot air into the intake ducting causing cooling problems (see picture above). The water discharged into the plant was causing problems, so plant personnel opened manual drains at their various workstations to drain the moisture, but adding extra compressed air load, making both compressors run even hotter. Not a pleasant picture.
The diesel compressor has been relocated and plans are proceeding at full speed to reduce compressed air leakage in the plant and add compressor capacity to improve pressure.