Recently I had a meeting with one of Van Air Systems specialty distributors that manufactures and distributes pneumatic and electric overhead

MHL Series Heatless Regenerative Dryer

MHL Series Heatless Regenerative Dryer

doors for automatic car washes.  The car wash bays that use pneumatic doors rely on compressed air to raise and lower the doors. This distributor called me a couple years ago looking for a solution to a problem for several of their car wash customers in the northern U.S.  The issue they were having was the pneumatic doors would not raise or lower in the cold winter months causing them to lose revenue.  The problem here was the wetcompressed air would freeze up in the supply lines to the solenoids and air cylinders that opened and closed the doors.  After much discussion we decided that our MHL heatless regenerative dryers coupled with a coalescing pre-filter and particulate after-filter would solve the problem.

The MHL series dryer will produce a -40°F Pressure Dew Point and protect the pneumatic components of the car wash year round.  It will also eliminate the freeze up issue in the cold winter months.

Fast forward to my meeting.  My distributor said that their customers were complaining that the MHL dryers were causing their air compressors to run when there was no demand for compressed air to raise and lower the doors. A heatless regenerative dryer needs ~15% purge air to regenerate the desiccant, which causes the compressor to cycle more frequently. I actually wound up talking direct with some of their customers and gave them suggestions on how to resolve this issue.  I suggested a flow switch on the outlet of the dryer to shut the dryer down when there is no downstream demand, or a relay tied back to the compressor starter to cut power to the dryer when the compressor shuts down.  This fix worked but it was not the real solution.

I asked my distributor if they knew how much compressed air was required to raise and lower the doors.  They told me it was less than 1 SCFM per door.  They also told me that the customers typically put in a much larger compressor than they actually need.  Typically, these automatic car washes only have a couple car wash bays and a tire inflation station. My distributor was asking me to quote the dryer size based on the compressor size rather than the actual SCFM demand.

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In-Line Desiccant Dryers from Van Air Systems

The real solution going forward is to install Van Air Systems Point-of-Use In-line Dryers and F200 Series Coalescing Pre-filters. The Inline Dryer uses a color change replaceable silica gel cartridge.  The cartridge changes from blue(dry) to pink(wet).  These dryers are the perfect solution for intermittent small flow applications that require a -40°F pressure dew point.

Dry Air Matters in all types of applications! For more information about our Point-of-Use, In-line Desiccant Dryers, or how to size a dryer properly for your application, Call us at 1-800-840-9906.

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