A major paint manufacturer is using RPA (Ronnigen-Petter) DCF and MCF self-cleaning filters on all of their painting lines in three facilities.  These filters require very little maintenance but can sustain accelerated wear if allowed to run when empty.  Instrument air is all that is required to run the filter mechanism.  The process is done in batches; and frequently the filters are mistakenly left running at the end of a batch, eventually damaging costly internal parts.

What was needed was a way to automatically operate the RPA filters only when required without the use of electric power.  F. S. Welsford Co. provided the solution with an OPW iso-ring mounted to an adjustable Solon snap-acting pneumatic pressure switch.  The iso-ring is a flowthrough pressure-sensing devise that will not clog in dirty service like conventional diaphram seals do.  It was mounted between the flanges on the paint feed line.  The instrument air line to the filter was run through the Solon switch.  This simple device opens the instrument air line to the filter only when pressure is sensed in the paint feed line.  The solution greatly reduced the maintenance costs for the filters, further reduced operator input and reduced instrument air usage at each facility.