Reply To: PCP compressor Filter
@steveuk, we’ve gone over this many times here on the forum. Here’s a reader’s digest version of the consensus here… No offense intended!
If we are filling SCUBA tanks from 0 psi, then a Pressure Maintaining Valve – PMV (which is a simple back pressure regulator) to maintain the filter/dryer at approx. 2000 psi is essential, else the filter media will be expended very rapidly. However, we air gunners almost never end up with our tanks less than 3000 psi or so, and certainly not down to 2000 psi. So, a PMV that keeps the filter/dryer at 2000 psi and up is pointless when we never let pressure get that low in the first place.
And, if the outlet vent valve on your compressor is near the bottom of the unit (as most are), and the outlet block is connected to the filter/dryer with a 12 to 24 inch high pressure hose, with the inlet to the filter/dryer higher than the outlet of the compressor, and the outlet of the filter/dryer higher than the inlet of the filter/dryer, a separate vent valve at the inlet of the filter/dryer is redundant.
Just my two cents, but based on sound engineering principles and common sense…