Ken I've got two of the Blue Drager SCBA tanks, they're 1 hour tanks, I fill them to 4.2K because that's where I've got my F10 set. The gauge on one tank is about 200psi lower than the other, the other one is right on the mark. They both have those Scott valves on them.
I'm a little late to the party here Ken but I have noticed that the gauge on my Yong Heng reads a few hundred psi low as well. I also noticed that if I wrap my hand around the gauge while it's running to sort of deaden the vibration it tends to read pretty much exact. Food for thought.I will probably upgrade the gauge to a higher quality liquid filled one at some point.
I'll have to pay closer attention next time I fill. I didn't notice my gauge fluctuating that much.
custumcutter, where did you get the fittings that are threaded unto your tank that the female hose from you compressor attaches to? Would I also need another gauge like you have or would the one already on the tank work?
avator, I understand now what you were referring to. Took me a while. LOL I use the double male foster fitting in between my rifle fill hose and the hose coming off of my compressor, right?