The light is on, but compressed air dryer is not drying
When we take a look at the refrigerated dryer in our compressor room, we all assume that it must be working if the dryer light is on. Then later that day or the next morning, water is showing up in the production equipment. So now what? Due to the complexity of an air compressor system, there are a number of reasons why a working compressed air dryer is not drying. Well, even though the dryer may be working, and there are 6 simple checks you can do.
Troubleshoot Your Air Dryer in 6 Simple Steps
- Feel the cabinet opening
Reach into cabinet opening in your dryer to find the condensate separator or the outlet line. It should feel very cold – around 38° F – and if it isn’t, then the dryer has a problem.
Action Item: Have the refrigeration circuit checked and make sure the condenser is clean.
- Check the valves
Believe it or not, one of the most common issues is that the bypass valves are either left partially open or do not close completely. If they seem to be closed, that is good, but you might want to check further.
Action Item: Check by closing all three valves and seeing if the air pressure after the last valve goes to zero—this may take a while if you can isolate system. If it doesn’t, then you need to replace the valve.
- Check the inlet temperature of the compressor
Inlet air temperatures to the dryer should be no more than 100° Fahrenheit. If you can put your hand on the dryer inlet pipe and it doesn’t feel hot to you, then that is good. If it feels hot to the touch, that may be the problem.
Action Item: Check the air-cooled or water-cooled aftercooler on the compressor to make sure it is clean and that the air temperature is no more than 15° F above room temperature. If it the aftercooler is too warm, you may have to remove it and clean it thoroughly.
- Check the ambient temperature of the compressor room
As mentioned above, your compressor room ideally should not be any hotter than the outside temperature, i.e. 90° F on a 90° F day. If the compressor room is more than 10° F above the outside temperature, you could have a problem for all of the equipment in the room since dryers are designed to run at 100° F ambient temperature.
Action Item: Get your HVAC or compressor vendor to review your compressor room ventilation to keep the ambient temperature from reaching 100° Fahrenheit.
- Check for condensate in the dryer drain trap
If a sizable amount is not accumulating from the trap, it means the dryer may be working but is not removing the water.
Action Item: Isolate the drain trap to clean or repair it. If you end up replacing it, REPLACE ONLY WITH A DEMAND TYPE TRAP.
- Check the low point in the piping system beyond the dryer
If there is any condensate that can be drained out, go back through the other steps. In the meantime, put a drain on this low point to help eliminate moisture in the system.