duratec7 wrote:
Is the unit you have intended to regulate (go in-line between the pump and rail) or to pressure relieve (between rail and a return line) which is more typical.
They function differently and if you are trying to use one for the other, you will have issues.
Operating on air, you may have issues that will not occur with fuel (or water, etc.) based on compressibility and viscosity differences.
Can you describe your test setup? I'm not really following your description of events very well, what adjustment are you making and which pressure starts to drop? If this is a return flow device, there should be no pressure on the outlet line, but you specify working with 70 psi air, so I am assuming you are supplying air from a regulator on a compressor to the inlet of the device, so that regulator will compensate flow until you get outside it's capacity (too much, or to low for it to regulate) and things will get funky fast. Regulators directly in series do not always behave as nicely as they might.
BINGO!
Yesterdays posts prompted me to question my setup. Well, I was treating this regulator like an air pressure unit. As Sgt Bowe, my basic training Sgt used to say, "We don''t do it thataway!". The problem was me, not the regulator.
Properly plumbed into our domestic water system, the little regulator gave smooth response up to its flow capacity.
Bill