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View Poll Results: Which Valve Body/Stem Combo?
Palmers Valve Body 7 70.00%
Palmers Valve Stem 7 70.00%
Check-it Delrin Body 2 20.00%
Check-it Delrin Stem 4 40.00%
Multiple Choice Poll. Voters: 10. You may not vote on this poll

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Old 07-31-2015, 12:59 AM   #11 (permalink)
Pancake
 
Join Date: Jul 2015

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Originally Posted by Spider! View Post
An interesting valve is the Madman rocket valve, which might make a good (entertaining) comparison.

I look at a few things on valves.

1) Port size. I make sure the body and valve ports line up and are the same size. Larger for lower pressure. No point in having extra steps in the flow path.

2) I like narrow, "high flow" stems for HPA or low pressure CO2. Just for the higher flow area.

3) Transition finish (the 90 degree turn) and stem support inside. Some valves have pockets in them that should cause more turbulence. Some have different stem tolerances (or o-rings on the stem).

4) Poppet shape. The closer to a flat disk you get, the more drag you have from flow, and the wider the pressure sweet spot will be with a lower maximum flow rate, compared to something profiled like the rocket valve. This goes against the forces on the springs and hammer to control valve dwell, which applies the pressure versus time behind the ball and along the length of the various barrel bores.

I've never found anything magical, but it's interesting.
I agree with you, it is all interesting. One concept I keep hearing but never understood and always assumed was negligible was the 'turbulence.' Is that the difference between valve stems that cause the air to flow in a more(or less) smooth path into the body? assuming same valve body and input pressure, would stems with different amounts of turbulence result in slightly different patterns of output pressure?


Quote:
Originally Posted by 608WIscompton View Post
Your planning on using this for a pump so i would recommned the palmers valve (if you really have money burning a whole in your pocket). Do not bother with an AKA valve, it requires heavy/stiff springs for it to work like advertised and would not give the smooth/light pump stroke you want. You could honestly just use stock wgp internals and go to your local harware store and mess around until you find a nice setup. Or you can talk to maggot and get a set of SLPS springs and not have to worry about finding a good spring combo. I personally use a palmers valve with a stainless wgp valve pin.

Edit: also stay away from the check delrin valve just because it is made of delrin. There is a reason most other valve bodies are made from brass
I placed an order for SLPS springs which I believe comes with hammer and valve springs. If I can swap the valve spring, what makes the AKA valve require stiffer springs? Its not the spring combo I'm looking for advice for on this thread so much as advice on differences between different valve body/stem combos and their effect on the flow of HPA. I am starting to lean towards the opinion that delrin is just a cheap alternative, but do you have any specific bad experience with it?


Quote:
Originally Posted by paintballedbackin88 View Post
I have mixed results with using the palmer valve stem. I've owned 2 so far, and one recently failed much sooner than I expected, as compared to a delrin valve stem.

I installed the palmer valve body and stem in a sniper I built over a year ago, and the sniper developed a leak down the barrel last week. This sniper was used fairly regularly over the year.

I pulled the valve and noticed that the rubber o-ring embedded into the brass body of the valve stem had become dislodged. I was unable to repair the cup seal and must buy another.

Perhaps I was unlucky, but I've never had that issue happen with a cheaper delrin valve stem/cup seal.
I imagine the leak down the barrel as you described was a damaged cup seal. Were you running low pressure with hard springs? Perhaps the valve pressure was not enough of a resistant force to the hammer causing the hammer to completely plunge the valve stem and also hit the body? Or maybe you or somebody else was pumping/firing it while it was not aired up, repeatedly smashing the hammer into the valve body. Just throwing that out there, but will keep the delrin valve stem/body combo in mind if durability turns out to be a problem. I put about 500 through my pump at the chrono every day screwing around tuning it, but only use about 250 in a day of playing.







Thanks for the replies guys, will eventually grab a palmer's and try to post some good results or observations. To look into: RAT valve, Rocket valve, Tornado valve.
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Old 07-31-2015, 10:18 AM   #12 (permalink)
Pancake
 
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So the rocket valve looks interesting, but if the hole that lets air from the lower tube to the top tube Is a given size, does it matter if the Valve body has more rooom for the air to flow but is still restricted at that one point? Or does all of the immediately available air in that pocket act as more of a capacitor and produce more flow?

On all of them, rat rocket and tornado, the Valve stems seemed to have low profile supports which you would think means more area for air flow when the Valve opens. The rat valve looked like the oring in the Valve body would make a good seal, for if I ever had cup seal leaks.

On the tornado valve body in particular, I noticed a wide bore for air to enter, which seems most ideal in the low pressure, high flow setup I'm going for.


Question, does anybody have both a Palmers and tornado valve to compare inner diameters where the air flows through?
Thanks again everybody

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Old 07-31-2015, 11:27 AM   #13 (permalink)
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Quote:
Originally Posted by pancake View Post
I agree with you, it is all interesting. One concept I keep hearing but never understood and always assumed was negligible was the 'turbulence.' Is that the difference between valve stems that cause the air to flow in a more(or less) smooth path into the body? assuming same valve body and input pressure, would stems with different amounts of turbulence result in slightly different patterns of output pressure?
Yeah, I don't think you can get much from stem design, other than reducing the obstruction which is kind of like "turbulence". But really, your dwell is controlled by the hammer, springs, cracking pressure, and drag over the poppet. That drag is from very fast flow with a high pressure differential. It is significant, especially at the point where the hammer motion and springs start to balance out. Normally, the flat poppet face should cause enough turbulence that the stem design is not a big deal.

Then consider where your flow is going after the valve face, two back to back right angle turns in an expanding passage, sometimes with another obstruction at the bolt tip. Then it all piles up behind the ball with little leaks around the bolt going the other way. It's all mostly turbulent when it comes off the edge of the poppet and never stops.

Narrow stems give you more flow area at the valve face and through the body, which seems to be significant. Even a 1/32" change in usable bore diameter can show up at the HPR adjustment.

The other end of stem design is the diameter of the hammer side. If you say it is sealed and not leaking while flowing, then the pressure on the pin diameter acts against the hammer. If you say it leaks and holds minimal pressure, that gas acts against the hammer, which may or may not be significant. Chances of designing that face in the bore to not have dynamic pressure on it are pretty slim. This is something else that is on the rocket valve, a skinny stem through the valve body to the hammer.

I think the pressure and flow effects on a poppet are useful, regulating forces, especially for CO2. The best use I can think of for the rocket valve would be a high pressure air setup (~600 psi).

I haven't tried changing the hammer side of the stem to make it larger. I'm wondering what that will do.
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Old 07-31-2015, 01:51 PM   #14 (permalink)
Pancake
 
Join Date: Jul 2015

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That would make sense. If running a low pressure setup, in addition to softer springs, one could get or machine a loger valve stem that would potentially provide more flow.

As for bolt, I'm using a ccm s6.5 bolt, so no venturing diffusion or anything. Just the right angle.
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