How do you fill from a Scuba tank without......

[tobar832]

I got a B-50 and have been pumping steady for a couple of months, no problems.  I bought a 3000psi SCUBA tank, its getting tested and filled now.  Should be ready in the next couple of days.      I bought the Benj 3000psi scuba fill hose with the small gauge.  It's about the size of a quarter.  Mu question is how do I fill the gun with with setup without a gauge on the B-50?  When I connect to the 80 cf tank with this Benj filler will the pressure shown on the gauge be the air in the tank or the air in the gun?  How do I keep from over filling the gun if this is the case?
    Do I stop and check the air pressure in the gun with the gauge on the pump maybe?  I going to put a larger gauge on the filler.  I got a better gauge already.

thanks in advance
Bill

[cactusrat]

The gauge will show what the pressure is going into the gun. Once it gets to the pressure you fill to, you shut off the tank.

You do not open the tank valve very much, or what ever pressure is in the tank will shoot into the gun (over filling it). Just barely crack the valve open until the needle starts to move. Fill the gun very slowly.

You have to watch closely and be ready to turn the valve off fast. You can always open the valve again to add a little more air, but you can’t take the air back out (without shooting it out).

Let me make it clear, I’m only talking about a 3000 psi tank here, not a 4500 psi tank. I wouldn’t use a 4500 psi tank without a regulator.

[tobar832]

cactusrat,

   Thanks, I got it.  I sat here and figured it out and your post confirmed it.  I got 3000psi for sure, there would be a problem with 4500psi.  With that pressure you need a gauge on the gun for sure.  Looked in the old B-50 too, it has a step by step outline on filling the gun. 

Bill