Air quality is important to a compressed air consumer — having a cool, clean and dry source of compressed air is essential, especially when food products are coming in contact with the compressed air system output.
A food products processor had purchased a very efficient cycling refrigerated air dryer a few years ago to condition its compressed air. This unit had operated successfully since then. When the old dryer had been operating, there was water contamination in the compressed air pipes that often found its way to the final product — causing food quality issues that required some product disposal.
But recently the water problem had returned. This was a head scratcher; the display on the dryer showed the dew point of the air at 38° F, yet downstream in the compressed air piping, there was water collecting in some down drops.
Thorough investigation by a compressed air service person found the problem: a condensate drain in the dryer had failed, allowing the condensed water to overload the dryer and pass downstream. Rust and scale from the wet side of the dryer had collected inside the drain, plugging it up and preventing the water from being removed from the system. The plant personnel did not realize the display on the air dryer actually measured the temperature inside the dryer, not the actual dew point.
The drain was cleaned out and return to service, with the air quality returning to normal. The plant made a few changes to ensure this problem wouldn’t happen again. A strainer was installed on the drain to prevent debris from clogging operation. And the compressed air output was rerouted to a dry storage receiver with a secondary condensate drain designed to remove any water, should the dryer drain fail.