When it comes to proper desiccant dryer performance one of the most common culprits resulting in poor dew point performance, is lack of prefilter maintenance and/or faulty prefilter drain operation. Most oil coalescing prefilter elements should be replaced at 2000 hours of service. Without a disciplined PM schedule to replace these elements and to confirm proper prefilter bowl drain operation, you run the risk of contaminating the desiccant bed.
Manual drain valves on the bottom of these filters are often problematic when not drained in a timely fashion, allowing oil to re-entrain into the airstream, causing oil to enter the desiccant chamber. Float type drains (internal or external) must be checked for correct operation as they may become fouled with oil/water emulsion and fail to operate properly. Electronic solenoid auto drains complete with off/on settable timers are most favorable when used with a strainer, as they allow periodic draining to … Read the rest