Hipac check valve

[antithesis]

I'm not sure if this is the best spot for this topic or not, but that's what the mods are for😂

Anyway, of the people here intimately familiar with the Internals of a hipac unit, I would like some conjecture here.

I have always been less than thrilled with the aluminum nail and o ring that makes the check assembly. The more I looked at it, it seems as though a cut short valve stem from a disco would be a more robust, reliable, and almost purpose built alternative, and one that if it works, should last a long time. If not, then perhaps the 2240 stem minus piercing pin or Benji 392 being softer may be better. I am keeping both aside for the inevitable failure of the factory offering, it already don't seal for &^^& under 1000 psi or so.

[Gerard]

The aluminum nail works, though it's less than a perfect fit. The failing part for mine at least was the O-ring, which squirted part way up alongside that nail. It's just too soft to deal with pressures over about 2,500psi. I ran my HiPAC at 3,000psi for a short while, but to do that I had to make a thin 95 durometer ring to replace the butyl one. Still holding perfectly well after several years. I'm sure there's a commercial urethane ring you could find to fit. Just make sure it's reasonably firm, so it doesn't follow the air up the gap between nail and drilled hole in steel.

[Gerard]

They're wonderful when they work. Mine failed to hold air in a few places, including where the extension tube threaded in at each joint. But after some work I got it all settled happily. Now it's in my son's 2240 carbine, has a Lane regulator installed in it, an accurate plenum mounted pressure gauge, and holds air for months. Just took some work and invention to make it so, in my case. And Alex, before what I hear about him having a stroke, didn't help matters by being an arrogant jerk about his subcontractor's sloppy machining.

[Wayne52]

The HiPAC's work good they do need o rings occasionally.  I've got several of them and they all work good.  I have noticed on my 3K one that I replace that o ring more when it hasn't been used in a while.  I think the next time I put one in I'll try using a polyurethane o ring.

[antithesis]

The HiPAC's work good they do need o rings occasionally.  I've got several of them and they all work good.  I have noticed on my 3K one that I replace that o ring more when it hasn't been used in a while.  I think the next time I put one in I'll try using a polyurethane o ring.

Oh yeah I went with a 90d poly ring right off the bat...I'm also experimenting with a few different valve seal materials as the hipac issue ones are no more, not to mention alot of us have had em blow. Everything from graphite gasket sheet, polyurethane sheet, and even an old sweeper belt, I personally have had no problem there yet, probably because I bored out and chamfered the inside radius I think it works better.  But again I know it's only a matter of time. 

[antithesis]

They're wonderful when they work. Mine failed to hold air in a few places, including where the extension tube threaded in at each joint. But after some work I got it all settled happily. Now it's in my son's 2240 carbine, has a Lane regulator installed in it, an accurate plenum mounted pressure gauge, and holds air for months. Just took some work and invention to make it so, in my case. And Alex, before what I hear about him having a stroke, didn't help matters by being an arrogant jerk about his subcontractor's sloppy machining.

Yeah he definitely has a bad bedside manner about prudent criticism, I personally think if he had put a hair more money into quality control he could have made considerably more on them... I don't Believe for a moment that the unit was responsible for any documented injuries that it got blamed for ( physically impossible), but there was alot of handy work, fine tuning to get mine up n running. I think however, that if the inside sealing face had been smoother, a harder and more permanent seal could have been used. And yes, with extensions I strongly recommend thread seal of some sort, even then I run a second band to cover the fact mine is a tiny bit off center from the rest of the unit.

Besides that, where did you put the gage on yours? Not to mention where you get a reg that fit?

[Gerard]

The gauge is installed on the left side of the main tube of the 2240 about midway between the valve and the threaded end. I made an aluminum gauge block with O-rings, drilled through the main tube and this gauge block and tapped tapered threads unto it for the gauge. Unfortunately that leaked, so I ended up having to use JB Weld steel filled epoxy on the threads, waxing the gauge threads and installing it and letting it cure. Hasn't leaked since. Been a couple of years at least, can't remember exactly.

The regulator is a Robert Lane model for CO2/HPA conversions. It was too large, so I turned it down very slightly in my lathe until it was an easy fit into the extension tube of the HiPAC. It's adjusted to 80bar, suitable for the low power the carbine is set up to shoot with.

[antithesis]

The gauge is installed on the left side of the main tube of the 2240 about midway between the valve and the threaded end. I made an aluminum gauge block with O-rings, drilled through the main tube and this gauge block and tapped tapered threads unto it for the gauge. Unfortunately that leaked, so I ended up having to use JB Weld steel filled epoxy on the threads, waxing the gauge threads and installing it and letting it cure. Hasn't leaked since. Been a couple of years at least, can't remember exactly.

The regulator is a Robert Lane model for CO2/HPA conversions. It was too large, so I turned it down very slightly in my lathe until it was an easy fit into the extension tube of the HiPAC. It's adjusted to 80bar, suitable for the low power the carbine is set up to shoot with.

Wait, does the gauge tap into the hipac, or does the block mate between the  hipac and gauge?

The tube of the gun isn't somehow pressurized is it?

[Ribbonstone]

Reads like the tube is pressurized....may be taking it wrong, but the dimentions make me wonder.  A little more information would help.
Would have had to make a skinny gauge block to fit in the rear section then drill though both the Crosman tube and the HiPac tube to get to that block.

 Believe this was a 2250 version...but as they (mostly) used the same front section,could calculate volume by the change in the rear (skinny) sections length.  It's not much volume,and folks wanted extentions to increase it...but I never had that urge to complicate the system.



In that infamous vid. of a guy miss-using one and putting a hole in his leg, the video evidence is that he was using just part of a HiPac unit and pressurizsing the tube (besides working on a PCP that was pressurized at the time).

Not pointing fingers...we all tend to mod things in ways we see fit. Sometimes it bites us.

Yeah...the check valve looks rinky-dink.  It actually works,although the giant azz spring used to power the check valve makes you wonder. 

Still keep 3 running (the old 2240 version didn't make the picture). Still working, sill useful little rifles....and after spending the time (and $) getting them set up and stocked,just haven't the heart to not keep them running.

But I do use the HiPac as it was intended to be used.

[antithesis]

I was hoping you would show up RS...you usually do on the hipac discussions.

That was my thought, I worry about you guys and it sounds an awful lot like the tube is under pressure here.  I don't trust the threads under that kind of stress. .it's your gun and do as you like but I'd make sure both the valve AND hipac are pinned or else you may end up with a valve or hipac unit in your leg😮

[mobilehomer]

Using a HiPac, the tube is under zero pressure. And as RSterne has explained, the pressure exerted through the small opening in the valve/HiPac port is very small. Mine has been holding 2000psi for over a month with no problems. With an 18" Crosman barrel, Disco TP and SSG, I get about 25 shots at 21 fpe. with 18.1 JSBs. VERY accurate, equal to my 14" LW with more power.

[antithesis]

Using a HiPac, the tube is under zero pressure. And as RSterne has explained, the pressure exerted through the small opening in the valve/HiPac port is very small. Mine has been holding 2000psi for over a month with no problems. With an 18" Crosman barrel, Disco TP and SSG, I get about 25 shots at 21 fpe. with 18.1 JSBs. VERY accurate, equal to my 14" LW with more power.

When used as intended yes you're right, but the way he described his mods it sounds like he is only using the front or otherwise modded it so the tube is pressurized

I charge mine to 3.5 k without issue. I don't recommend that but I am well aware that if something fails it won't be my valve screws, threads or main tube

[Gerard]

Geez guys... talk about getting your panties in a bunch. Okay, so I was brief in my comments about the gauge and regulator, but that's because last year sometime I made the unforgivable error of having a VPN active when visiting GTA, and for reasons the host can not figure out, this resulted in a permanent ban of my PC. Posting lengthy comments from my phone via LTE connection is all I have left, and it's tedious. But I'll try...

Here's a picture of my son's (cutely painted sparkle blue, per his request several years ago) 2240 carbine with HiPAC, single extension tube, and gauge installed.


- The gauge block is indeed rather small, allowing for just a 1/4" hole through it for passage of air through the plenum volume. And yes, the hole was drilled through the Crosman tube, through the HiPAC, and through to the vent hole in the aluminum gauge block, which I drilled offset substantially so as to allow deeper threading into the block. As 2240 HPA conversions go this still leaves plenty of air at the desired ~850psi in the plenum. You'll note the gauge reads a bit below 800psi - that's because he hasn't shot it since October, and he shot it down to about that level before we left the informal HFT gathering. Thing gets about 25 good shots per fill.

- The whole of smaller portion of the HiPAC acts as the regulated pressure vessel, or plenum volume, minus the roughly 2cc for the gauge block.

- As I've written long ago in HiPAC threads, the nipple at the end of the HiPAC presses against a stepped seal made of Ertalyte mounted in the modified tip of the brass valve, as supplied HiPAC seals just squirted out above 2,200psi.

- The pressure in the Crosman tube is atmospheric. That's because I seal my pressure vessels properly. The front grip mounting bolt is drilled to 1/16" in the bottom of it's Allen socket, all the way through, as an emergency purge vent which in the event of a leak would spew air straight down, at worst endangering the left hand of the shooter with a bit of cold air.

- The valve has been pinned in 5 places, very strongly, in addition to a 1/8" aluminum disc with two more smaller bolts behind the valve which I installed both for additional safety (this is MY SON I'm talking about here!) and as a valve opening limiter, with an O-ring behind that (bstaley) for additional limiting. This valve is never going anywhere. It's a permanent built, at least as far as the valve is concerned. If it ever fails (unlikely - silicone grease on the urethane valve body O-ring, custom delrin poppet on a drill rod, everything as tweaked as can be) we'll just toss the thing and I'll get him a new PCP. It was a fun adventure building this thing in all sorts of ways besides its final form, but this is it's FINAL form.

- The HiPAC worried me during the whole scare about these things, but by dumb luck I got one with an exceptionally thick wall at the part where people worry they've been cut too thin. Mine is over-built, so no complaints there. Still, I mounted a strong barrel band and have it firmly clamped at the front of the HiPAC, as I wouldn't want him dropping the thing and bending it off, releasing pressure suddenly. The barrel should add enough strength to prevent that.

- The textured stuff is just some rubber over cloth material glued on as a foregrip.

I can't think of anything else to assauge the sky is falling sorts of worries going on here. But ask away if you can come up with more concerns. Believe me though when I say that since initially experiencing a bit of a mini disaster of my own with this HiPAC owing to the first valve face seal venting and pressurizing the main tube, making for a very, VERY frightening and slow disassembly involving a bench vise and eye and ear protection and standing to one side... all my subsequent efforts with the little monster were made with extraordinary caution in mind and in practice. If I weren't such a stubborn cuss I'd have just tossed the thing and moved on, but I made it work.

[antithesis]

Lol it's ok buddy, just a matter of sheer intrigue, really couldn't picture it without elaboration, a pressurized tube sounded most likely..thanks for clarifying, and that sounds like a machining nightmare to get right, my hats off to you sir.

My response was primarily to mobilehomer, to make clear that I understood how the seal surface area makes the hipac much easier to secure than tube fill...

And YOU are the ertalyte guy! Ok, didn't you say at some point you tried delrin and it boiled or outgassed or something? I'm testing different seal material since Alex is down for the count and not everyone can make their own seals, I'd like to make a reliable, user friendly solution to make available to the average hipac owner

[Gerard]

Yeah, guilty as charged. Ertalyte being a trade name for some fancy hard plastic with low friction and extremely low distortion under a lot of pressure. I bought a rod of it for something else but it seemed the next obvious thing to try after the delrin distorted weirdly and started leaking. Others have had good luck with delrin there, but even though I'd polished the tip of the HiPAC thoroughly it leaked after a while. Last time I looked at the Ertalyte it looked like it was fresh off the lathe. Zero distortion. Of course that requires perfect mating surfaces, but I'm pretty good with those. Being fussy about details makes for good quality repairs to violin family instruments, among other things. Also makes me somewhat annoying to deal with at times.

I suspect even brass might work, or copper maybe. Of course the harder the material, the harder you need to screw in the HiPAC to get a good seal. So maybe Ertalyte is a good balance.

[antithesis]

Yeah, guilty as charged. Ertalyte being a trade name for some fancy hard plastic with low friction and extremely low distortion under a lot of pressure. I bought a rod of it for something else but it seemed the next obvious thing to try after the delrin distorted weirdly and started leaking. Others have had good luck with delrin there, but even though I'd polished the tip of the HiPAC thoroughly it leaked after a while. Last time I looked at the Ertalyte it looked like it was fresh off the lathe. Zero distortion. Of course that requires perfect mating surfaces, but I'm pretty good with those. Being fussy about details makes for good quality repairs to violin family instruments, among other things. Also makes me somewhat annoying to deal with at times.

I suspect even brass might work, or copper maybe. Of course the harder the material, the harder you need to screw in the HiPAC to get a good seal. So maybe Ertalyte is a good balance.

I was considering lead myself, and I have flexible graphite sheet, but I'm examining elastomers first, and for that I got a few sheets of 95 duro urethane sheet 2mm thick

I wanted to try filled or expanded ptfe but man it's expensive

One other avenue I'm examining is a softer elastomer, and a piece of tube flared on both sides, like a grommet, so the pressure primarily affects the metal while the softer material picks up the sealing slack...not sure about that yet though.

Funny how I started this thread examining the check seal and now we made it to discussing the opposite end😆

[Gerard]

It's all more or less the same thing, seals. And the sloppy tolerances and in places poor design have made the HiPAC into a significant tinkering hobby all by itself for some. I'm glad to see the SafePac crop up though. The finish looks rough, which might indicate internal work not being tidy either, but the self contained nature of the thing is neat, especially that it doesn't have to rely on a face pressure seal at the valve. I like the built in gauge too. Unlike some, I don't worry about front mounted gauges. Guns don't magically point themselves right at your eye, and a 45° angle should be more than sufficient to check pressure. That's why some manufacturers of Olympic level air pistols put the gauge on the front of the cylinder.

[antithesis]

Safepac, huh? I was unaware, but saw something similar being made overseas, is somebody mass producing them?

[Gerard]

Someone here mentioned them the other day. First I'd heard of them as well. Only place I know to get them is eBay, from the maker apparently:
https://www.ebay.com/itm/crosman-2240-pcp-conversion-carbon-fiber-inlay-/184116091990?nav=SEARCH

[antithesis]

Safepac, huh? I was unaware, but saw something similar being made overseas, is somebody mass producing them?

Froggy on ebay is making them.

It's all more or less the same thing, seals. And the sloppy tolerances and in places poor design have made the HiPAC into a significant tinkering hobby all by itself for some.

That really is the only issue with the hipac, tolerances, be it size in the tube/wall thickness/threads and seals. Plus possible valve poppet damage depending on use and what level of quality the material really is.







As far as guage placement on the safepac, i also like it on the front but the fill valve is ugly..... if it was a removable probe id possibly buy one for (maybe) my next 2240.

While I don't mind pinning, this looks worth looking into