A large home products manufacturer had its compressed air system pressure hooked up to their building management system. System pressure was continuously monitored and alarms would be sent to facility management if the levels dropped below a set low pressure threshold.
The facility was suffering an ongoing problem. Many times a day, low pressure alarms would be received, resulting in the compressor operators going to the compressor room to investigate — only to find the pressure at the compressors was at proper levels. Additional monitors were placed on the system and found the pressure loss across the refrigerated air dryer and filters reached as high as 20 psi during system peaks.
Initially, this system loss was blamed on the system filters, but measurement revealed that this loss was at low levels. The actual problem was pressure loss across the air dryer. The dew point display on the dryer was at high levels, which indicated a problem. Service personnel were called and found that the refrigerant level in the dryer had reached low levels causing the internal dryer temperatures to fall below zero, causing the dryer to ice up inside. This ice blockage restricted flow and caused a large pressure differential.
The dryer was repaired and the pressure drop returned to normal. The alarm problem was solved.