weird question!
what would be a good volume for a prechamber? i’d need enough volume to hold 2 shots worth. im not shooting just from a prechamber, i am using a remote line, but for consistency id like to have enough air for 2 full power shots. im gonna have one made w/the OD of the edge tank, no idea on the ID though, thoughts? im going to have a modded condor valve, so i can get some good power for a .25 build ive got going…any help would be great, thanks guys!!
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well damn it roach! you just destroyed my hopes and dreams!!! FML! no but seriously, you’ve scared me! see, im hoping to use a 90 cu in tank, 4500 psi regulated to 2600 psi to the prechamber. the prechamber is not going to be anywhere near the condor tank size, in fact, its going to be an Edge size O.D. but im not sure of the i.d., but id like it to be 3-4″ long. i was hoping to get 850+ w/a 70gr slug with this set up… but looking at roaches numbers i might not be able to
The beauty is, is that the UK bottles are rated to 250 BAR or 3650psi
I get valve lock on my big bore valve at that pressure, but I just need a hammer and spring butch enough to open it 😀
Dave
How I do it.
I have a long canted ETAC, that and the AF tank acts as my prechamber. I have Shoebox compressor, and I have a 4500PSI Pygmee tank. with a 3 foot line.
The ETAC is connected to the main AF tank and provides me with all the prechamber I need, the Pygmee acts as both a manual regulator and reserve tank controlled by how much I put in it.
in the picture there is a 3000PSI gauge, this has been exchanged for a 4500PSI gauge.
Now what I do is to fill the tank to my desired level, which IS NOT 4500 PSI, when it is tethered.
Then I can experiment with different pressures, springs, hammer weights, and projectile weights, ie., 3200PSI and a 105 gram hammer and Condor spring with condor spacer as a preload, produce 1060 FPS with 24.4 King, whereas with the 3000PSI fill and stock Condor firing mechinism gives 960 FPS with the 24.4 King.
Right now I am just starting on this, and I am filling the AF tank to 3200 PSI, what I need in the future is a tank regulator that Joe and Van each sell, and a highflow valve that Walt will make for me. When that is acomplished then I can set the tank regulator pressure at the PSI level I found to work best.
I read from Pabs writing that I can fill the AF tank much higher. When I find the correct combination, for the interm the Pygmee tank will be filled to that level and give me much more volume and almost a regulated output, or at least that is the goal.
At the 3200 and 105 gram hammer, preload ect., I have no valve lock, just a steady minute decrease in velocity, whereas at 3200 PSI and the stock AF Condor hammer and spacer do give me valve lock for two or so shots.
Roachcreek
everyone, thanks! im actually working w/Marmot Militia on my gun! the 4500psi tank has a JDSAirman valve that’ll lower the pressure to 2400-2500 psi, and thats whats going into the prechamber. and yes rob, you got my thought process on the setup: 4500 psi tank, remote line connected to prechamber that has the condor valve in it. and the volume of the prechamber is what im trying to figure out- i dont want to run into the probs that everyone’s stated…i know that the O.D. of the prechamber will be the same as an edge tank- i just dunno the I.D. or the length- i want enough volume for 2 full power shots, just to be safe…
If I am reading you right… you have a 4500psi tank that will unload to a prechamber and that prechamber will have a AF valve attached to it, yes? In that configuration, you are going to get valve lock out the ass.
You will have to regulate the pressure coming out of the large tank. That pressure will dictate how large your prechamber volume is. If the volume of your prechamber is too small for a given psi output, you’ll not be using the air efficiently and velocity will suffer.
Marmot Militia has had the same issues with the E-TaC in that he had to find a happy medium between the volume and pressure.
You are first going to need to figure out your constants… things you will not easily be able to change…. and then figure out your variables.
For example… if you build a prechamber with a volume of X, and thats the only prechamber you have… then you’ll have to set up the rest of your system (pressure, hammer weight, valve spring, hammer preload) to take advantage of that volume. If you have a set output pressure… then you have to optimize the prechamber volume, hammer weight, hammer spring, valve spring….. etc
Make sense?
Cab’ If your prechamber is at 3000psi, your valve output will be 3000psi. If you got 4000psi going in there, then you will have 4000psi coming out etc. The size of the prechamber makes a difference to power too. If its too small, you will only get a little ‘sip’ of air at the given pressure. It may be high pressure, but just not much of it. No point having a big hungry V8 if the carbs are tiny.You want high pressure and a decent volume of air on each shot.
okay, i need some duct tape for my head, cuz dave, you just blew my mind….i thought thats what valves do- regulate air coming out of a tank…so now im really confused!!! okay, here’s the set up in my head: i have a 88 or 90 cu in tank, 4500 psi. im not sure of the output pressure needed from the main tank…im guessing 2-3k? anyhoo, there’s a remote line from the tank to a prechamber, that the AF valve (modified) is threaded into, and from the air in the prechamber, the AF valve operates… im trying to work out the size of the prechamber…maybe we’re not looking at the prechamber the same… ugh, man i wish i had a better way to describe things!!!
Valves don’t have an “Output pressure”
I was using a regulator to take 3000psi air to a pre-chamber of 2000psi air, doesnt matter where the air came from etc.
Wtih that 2000psi air, I managed 1000fps with kodiaks, with 3000psi? who knows?
I don’t get what information you want?
Dave
yeah, i understand the 3k tank 2k output, but what im not getting is what reg is doing the 2k output… or was dave just running the normal AF tank/reg set up. see, im running a remote set up, and my modded valve will be connected to a prechamber, and a remote line will run from the prechamber to another, much larger tank. Hmmmm here’s a question: if i modified a valve for more flow, is that going to up the output pressure, or does that just make the output flow better? and what is the standard output pressure of a factory condor valve? thanks everybody for all the help!! i really appreciate it!
3000psi tank pressure, regulated output at 2000psi.
only 2k output from your tank? hmmm…could you explain your setup a bit more? i thought the tank psi would be 3k output because the gun valve would be 3k output…im confused.
Well, the pre-chamber I had on my 2000psi reg was an 18mm hole that I can’t quite remember the length but Im pretty sure it was around 1.5 cubic inches.
That managed to get 1000fps with 31 grain kodiaks with 2000psi air and a big bore valve.
Hope that helps.
Dave
hmmm…i suppose i could word it a bit different? how much air does a modded valve use to push a .25? a ball park? i dont want to go too big on the prechamber…
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oh- and i was hoping to use a 110 gram hammer w/matching spring, forgot to put that. im hoping to get a high-flow from walt too… along w/some other stuff for the gun 😈