The operators at a lumber mill were having production problems in two of their machines. Annoyingly, critical sensing eyes were getting blocked by occasional pieces of bark as the logs went by. After enduring this for quite a while the maintenance department finally took matters into their own hands.
The plant had a welding department, so they quickly whipped up a couple of homemade nozzles out of channel iron, with a slot fashioned at the edge designed to blow down on the eye to keep it clean. They didn’t really know what size of slot was required so they took an educated guess — and lo and behold the first try worked!
Months later, while investigating the compressed air system to determine the reasons for a lack of capacity, a compressed air auditor found these blowers and measured the flow with a flowmeter. He found that each blower was consuming 50 cfm. The calculated energy cost of this blowing for two nozzles was $20,000 per year as these operated continuously, even when there was no production!
The maintenance staff were quite surprised by this cost; they felt that compressed air was a free utility. They had made nozzles in house to save from buying somewhat expensive engineered specialty nozzles. A check on the optimized nozzle specifications found that $15,000 savings could be gained by purchasing the optimized nozzles. The cost saved by making their own was $1,000.