rsterne wrote:
Near as I can figure, the reg. is not working.... Is the tube vented?.... supposed to be vented?.... Whether or not your plenum is large or small, you should get a constant velocity within about 1%.... The larger the plenum, the higher the velocity, but it's not linear.... A 1" long space isn't too much volume....
RE the velocity at 1000 psi, 900 sounds too fast with 14.3 gr.... but my AT44 shot that at 115 bar (~1700 psi) when stock....
Bob
I was hoping to hear from you Bob. Yes properly installed with vent. No air leaks from the vent or through the plunger. It works perfectly on tthe test stand never going above 1000 psi on the valve side. I filled the tube to 2500 psi and the outlet side stayed at 1000 psi. I let out some air through the bleed valve. The pressure dropped momentarily and then returned to 1000 psi each time. I think I'll try a heavier valve spring, and a teflon plug in the stand off to mimic less air space. I'm thinking the problem might be the weaker valve spring. The valve might be opening too far and staying open longer allowing some air in from the high pressure side to combine with the air in the stand off as it exits the valve. On high pressure the rush of air from the high pressure side might cause 2 things. First it makes opening the valve harder, so the pellet speed is low, as in my non regulated gun. Secondly, as the high pressure drops, the valve stays open longer allowing more air through the valve ant the pellet speed increases as the pressure drops. Then it passes a certain point around 1400 psi when everything reverses and pellet speed drops. When the pressure drops to 800 pse, the gun vents all the remaining air unless I cock the gun to stop it. The only problem with this theory is the hammer strike should not be affected by the high pressure side on striking, as the counter pressure should only be 1000 psi constant. However the incoming air is high, so it rushes in faster to refill the stand off and valve,so should have the affect of starting off with a higher pellet speed and drop steadily as the pressure drops.