Many air compressor operators choose to use timer drains to remove liquid that is captured in separators, traps, receivers and filters in a system. Rather than using gravity feed or a float system, these drains open and expel the liquid, and an amount of compressed air, from the system after a set number of minutes.
Because the valve is solenoid operated, the flow of compressed air gives a very forceful blast, powerful enough to blast through the dirt, scale and debris that may collect on the bottom of the condensate traps. This is a great benefit — this simple circuit is very reliable. In fact, by far the most common of all drains is the timer style.
But sometimes these drains are misused; recently a compressed air room was visited by a compressed air auditor, and six timer drains were found on the single compressor system. One drain on the compressor water separator blasted for 15 seconds every minute. Another on a wet receiver blasted for 20 seconds per minute. Two others on dryer inlet and outlet filters blasted for 10 seconds each per minute. And finally, a timer drain was installed on the air dryer, blasting for 15 seconds every minute.
The compressed air auditor, becoming concerned, tried to hold a conversation with the compressor operator, but the discussion was impossible due to the high noise level of the blasting drains!
The auditor investigated and found that the drainage was only recently increased because water was getting into the system despite the refrigerated air dryer. But the problem was obvious: poor ventilation was causing the compressor to output very hot compressed air overloading the air dryer. Unfortunately, in this condition, no amount of drainage in the compressor room was going to solve the moisture problem in the cool, air conditioned plant. Using excessive drainage was only making the problem worse — not to mention costing the company thousands of dollars per year in extra energy costs.
Some tips about condensate drains:
- If you are having moisture problems, it is very likely that the cause is something other than the timer drain, so check compressor discharge temperatures, and dryer condition.
- If you use timer drains, ensure that the blast time and frequency is adjusted to minimum. If large amounts of compressed air are expelled along with very little water, it is likely the drains are blasting too much, so reduce the blast frequency and duration.
- Install a strainer before the drain to ensure the blast orifice does not plug with debris.
- Consider using float or airless drains, especially in non-critical locations like filters and receivers.
- Test the drains regularly to make sure they work.