Condensate Drain Options for Compressed Air Systems

Football Tackle

In “Football, Compressed Air Systems, and the Importance of Teamwork”, we discussed the importance of choosing a quality condensate drain for your compressed air system.

Just as putting the right linemen in the game can make the difference between winning and losing, choosing the right condensate drain for your system can make the difference between a smoothly running system and a costly problem.

There are many options to choose from in condensate drains:

  1. Cracked ball valves
  2. Timer operated electric solenoid drains
  3. Electric rotary ball valve drains
  4. Float drains
  5. Zero loss drains
  6. Electronic zero loss electronic drains

Cracked Ball Valves

I am not even going to address cracked ball valves. If you are even considering that option, this article is not for you.

Timer Operated Electric Solenoid & Electric Rotary Ball Valve Drains

Timer Operated Condensate DrainsSolenoid operated drains and electric rotary ball valves fall into the same general category. Both operate based upon preset intervals. They are inexpensive and readily available. However, they are inefficient and do not always eliminate all the condensate.

Most of the time the interval settings are never adjusted after installation – but the humidity changes dramatically season to season. The timer operated drain traps will either allow expensive compressed air to escape or they close before all the condensate is evacuated.

Over the years I have witnessed gallons and gallons of water in air receivers of properly working timer operated drain traps. The last point is, in this increasingly digital world of monitoring there is no option to remotely monitor these drains.

Float Drains

Float Drains

Generally these are found inside the coalescing and particulate filters. They are again the least expensive first cost. The good thing is they are somewhat demand driven – whereas they only open when condensate is present and typically eliminate most if not all of the condensate before closing. The problem I have with this option is less pronounced than the before-mentioned styles. The primary issues are the lack of remote monitoring, not truly a zero loss option and the expense of annual replacement.

Zero Loss Drains

Zero loss drains refer to the ability to expel the condensate without wasting any compressed air. They come in two (2) variations, float operated and electronic. In both cases consideration to the size of the system and where they are placed in a system need to be addressed.

Zero Loss Float Drains

Zero Loss DrainsFloat operated drains are rather self-explanatory. As the level of condensate builds inside the drain a float slowly rises until a point at which a valve opens. The condensate is pushed out of the system using air pressure. A small amount of condensate remains when the float closes ensuring true zero loss of compressed air. The issues with these drains is the lack of remote monitoring and the limited ability to provide freeze protection.

Electronic Zero Loss Float Drains

Zero Loss Electronic DrainsElectronic zero loss drains cover all the bases from efficiency, true zero loss capability, remote monitoring and the ability to provide freeze protection.

These drains use a capacitive level sensor to open and close a solenoid. As with the float drains above, a small amount of condensate remains ensuring true zero loss operation.

Capacitive Level Sensor
Capacitive Level Sensor
Dry Contact Electronic Zero Loss Drains
Dry Contact Sensor

But unlike its float drain counterpart, the electronic option adds the ability to trigger a dry contact in case the drain fails. In addition a red LED is illuminated when the drain fails to discharge the condensate in a predetermined amount of time.


If you want to have a compressed air system that performs reliably and efficiently under all conditions – the heat of summer and the cold of winter – careful consideration must be made when choosing all the components that comprise a compressed air system – including the lowly condensate drains.

To paraphrase Williams James:

“A team is only as good as its weakest player”
“A system is only as good as its weakest component.”

If your compressed air system is disappointing you or causing you too many headaches, give us a call at (540) 728-1147 or email us at <a href=””></a>.  We will perform a no cost walk-through inspection and bring to your attention areas of concern.

See you next week!