ON FACTORY compressed air systems it’s good practice to fit air isolation valves like this one below (A) fitted to a stamping press. It shuts off the air when the press is idle but in case of valve failure a bypass (B) is provided. This one is closed now, but moments before the picture was taken we had found it open, defeating the automatic air shut-off.
Just before we moved on I noticed a hose connected to the valve at one end and nothing at the other end. It was the air supply to the pneumatic actuator on the air valve itself, and without it the valve would never close anyway. Somebody had decided to adopt a belt-and-braces approach to wasting air by disconnecting it (C).
The problem of open bypass valves was commonplace and well known, but nobody had thought to establish the root cause. What compelled operators to defeat the system? It turned out that they sometimes needed air on the press to apply the pneumatic brakes on the flywheel after the main motor had been turned off. A simple push-button over-ride will solve that issue.