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GGDT and check valve help

Posted: Sun Dec 10, 2006 5:41 pm
by bugsingelyn
Hi,
I am new to this forum, and let me say I like it so far, but I have a few questions about GGDT:
1. What is inner and outer diameter for the Reservoir Data secion? Is that for coaxles maybe?
2. When it says "seat diameter" in the Valve section, which seat is it? Maybe...on the piston?

Also, how do people put check valves in their pistons? Do they make their own? How? Could I put it on the outside of the gun, from the pilot area to the chamber, with some hose and a check valve bought from mcmaster to fill the rest of the tank? Would air just go by the o-rings that I plan on puting on from behind the piston? I think I will mostly be using a bike pump, maybe emergency compressors occasionally.

Whoa, sorry for all of the questions, but I guess it is better to ask them all in one topic. Thanks so much for the help.

Posted: Sun Dec 10, 2006 5:57 pm
by boilingleadbath
1) Yes, it's for coaxials... didn't you read the documentation?

2) I believe it's the diameter of the barrel's hole if you've got a standard barrel-sealing piston valve.

3A) Generaly, they make their own checkvalves; construction is simply a rubber flap over a hole in the piston.
3b) Yes, you could plumb a check valve externaly
3c) Hu? What do you mean by "o-rings thath I plan on puting on from behind the piston"? Could you explain how they are set up?

Posted: Sun Dec 10, 2006 6:05 pm
by bugsingelyn
Oh, im sorry, when I said "Would air just go by the o-rings that I plan on puting on from behind the piston?" I meant it like "Would air leak by the o-rings on the piston if I fill the chamber from behind the piston?"

Posted: Sun Dec 10, 2006 10:16 pm
by squeaks
If the o-rings are done correctly air won't leak past them, that is why a check valve or a small equilization hole is needed.

Posted: Mon Dec 11, 2006 9:34 pm
by bugsingelyn
So, what do you suggest for the size of the equalization hole? I made my piston out of two 1-1/4" end caps, so would I just drill one hole in the back and a few on the sides?

Posted: Tue Dec 12, 2006 3:37 am
by Pete Zaria
First, I assume this is a barrel-sealing piston, not a chamber-sealing?

If so, you want to drill the equalization hole near the outside edge of the piston - where the piston surface is exposed to the chamber, not the barrel. Otherwise, air would leak out the barrel.

I don't think you need a very big hole. Maybe 1/16th" or so? Start with that and drill it out larger if need be... External equalization is another option, too.

Peace,
Pete Zaria.