An automotive plant was having trouble with a finishing tool. The device was sluggish and would easily stall. It had no power. It even sounded weak. It didn’t have that nice “Vrrip, vrrip!” sound like a normal air tool. A compressed air auditor was called in the investigate.
The auditor took one look and frowned. His eyes traced the supply hose all the way back to the down drop from the distribution header pipe. He shook his head and beckoned the maintenance manager to join him, telling him he had found the problem and it was the typical problem of, “the last dirty 30.”
Seasoned compressed air auditors know that the biggest pressure drop in the plant is typically in the last 30 or so feet of compressed air components. The hoses, quick connectors, filters, regulators, and lubricators connecting a tool to the main header are often poorly selected, and the result is usually excessive pressure loss causing poor tool performance.
The auditor pulled out his trusty test jig, simply a T-connection with a pressure gauge and a male and female quick connect coupler on the other ports. He connected this in series with the poorly performing tool. With no air flowing with the tool at rest, the pressure read 110 psi. When the trigger was pulled, the pressure at the tool fell to 44 psi.
The auditor pointed to each of the four quick connect couplers installed along the supply hose. He pointed to the hose itself — only a ¼-in. size — and explained a tool consuming about 20 cfm cannot be adequately fed with small hose, it needed at least 3/8-in. And then he pointed to the 50-ft reel of hose mounted on the wall. All these undersized components were contributing to the 66 psi pressure loss.
The hoses and connectors were upgraded in size, and the length of hose shortened. After the improvements, the tool received an inlet pressure above 90 psi, greatly improving performance, back came the crisp “Vrrip vrrip!” sound — and smiles on the faces of the joyful operators.