Contaminants can enter a system at the compressor intake or be introduced into the airstream by the system itself. Lubricant, metal particles, rust, and pipe scale are all separated and filtered out, but it’s the drains that have to operate properly for the filters and separators to be successful in completing their task.

Drains can be found on an intercooler, aftercooler, filter, dryer, receiver, drip leg, or at point of use. Drains come in many types and variants for all these applications, some quote fancy, but they fall into these basic categories. No air waste – timer operated – open tube – none (yes that is a drain choice).

How do your drains improve system efficiency? Besides the obvious savings of compressed air with a no-waste drain choice, there are other less obvious ways drains can save energy or cost you energy if not properly maintained. They are key components in the quest for system efficiency and reliability.

When a drain fails to eject all of the condensate collected, oil and/or water will collect, affecting -- filter efficiency – causing carry over into the system – allowing freeze-up in the winter. On multiple stage compressors moisture carry over from the intercooler may allow liquid into the next stage causing premature wear and possibly a catastrophic failure. On your refrigerated dryer the temperature indicator may still read 38F, but if your drain has failed you’ll have plenty of water downstream. Slugs of water due to drain failure can cause major problems in a desiccant dryer. Drains stuck in the open position can be a major source of wasted energy in some plants.

 

Drain Types

No drain. Whether you choose to not install a drain, not repair a failed drain, or install a manual drain, the outcome is the same and falls into this category.

We see this all the time. Think about it. You purchase a filter for a reason. If it is only to collect dry contaminants (a desiccant dryer after filter or carbon adsorber for instance) then not having an automatic drain may be acceptable, but if there is the reasonable expectation of any liquid collecting, then why don’t you allow for that liquid to be ejected? Done manually on every shift change you say? Very doubtful, and besides, the amount collected can change with load and season and needs to be ejected at irregular times.