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Thread: Regulator Woes

  1. #1
    Senior Member sholo's Avatar
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    Regulator Woes

    A few weeks back the reg on my 2260 (1500 psi output) let go and 'burst' the burst disc. I wasn't shooting it at the time, but noticed it when I got home from work and the gauge was at zero (had been at 2200 +/-) Took reg apart to see what went wrong (like I know what to look for...), but didn't see anything obvious - no dirt, nicked o-rings, etc...That's not to say there wasn't any of the pre-mentioned culprits, just that I didn't see any...

    Anyways, ordered a regulator rebuild kit from Eric, installed it (being careful no contaminates sneaked in) and said a small prayer before pumping it up. It held...WooHoo! Over the next 2 weeks I fired off probably 175-200 rounds (1600 psi output), pumped the bottle up several times, everything worked as it should. Then last night as I was working on my AR stock, the burst disc suddenly let go again! Startled the bejeezus out of me and the nephew!

    Any ideas on what I'm doing wrong? It's been humid as hell here for the last week or so - could water molecules be getting past the filter (which I also changed recently), causing said problems?

    Any advice or suggestions would be greatly appreciated.

    Todd
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  2. #2
    Moderator rsterne's Avatar
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    I assume you are running a 1.8K burst disc.... They have a tolerance, from what I understand of plus/minus 200 psi.... so could blow as low as about 1600.... Regulators are also not spot on, running plus/minus at least 50 psi, maybe 100.... so you could just be on the high side on the reg and on the low side on the burst disc.... I have had a couple blow running 1600 psi, none (yet) running 1500.... Another culprit could be the gun getting hot.... While temperature has little effect on HPA, it does have some.... If the gun is used at 20*C and then warms up to 35*C, the pressure changes by the degrees Kelvin (C + 273).... So the pressure increases by 308 / 293 = 5.1%.... If the regulator was set at 1600, when it warms up 15*C the pressure in the gun would increase to ~1682 psi.... Add in the tolerances, and POP goes the disc....

    Scares the heck outta ya, don't it !!!

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  3. #3
    Administrator AirGunEric's Avatar
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    All these regulators are a bit "variable" I have been told- ie. set one for 1500psi it could 'creep' around a bit to +/- 10%. Mind-you that would only be 1650psi maximum, so why is it popping the disc?

    Bob had a chart somewhere around that laid out the different shim configurations/alignments for different pressures- if a shim is installed one-way instead of the other, this can can change pressures- my idea being that something is not correct and the pressure is going about 1800psi.

    The other thing to mention, not that anyone is doing this- but it might be worth stating it for people coming across this in the future when they have issues, is that you cannot fill a bottle through the output side (i.e. the paintball hose connector)- once you hit 1800psi, the disc will burst.
    I'd say I care- but I'd probably be lying...


  4. #4
    Administrator AirGunEric's Avatar
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    Ah - crossing typing there.

    I think Bob has the right idea- tolerances at both extremes perhaps overlapping.

    Mind-you, the Regulator manufacturer was the one who mention the possible 10% tolerance on regulator settings- has Bob only observed a 50-100psi difference? That's better than they had stated in the past.
    I'd say I care- but I'd probably be lying...


  5. #5
    Moderator rsterne's Avatar
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    I think the manufacturer's 10% is how close they can set it.... and I've never seen one out that far, never over 100 psi off.... Once set, however, the pressure will drift over about a 50 psi range depending on whether the tank is full (higher) or empty (lower)....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  6. #6
    Senior Member sholo's Avatar
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    Here is a bit more info/questions for ya.

    You are correct on both accounts, Bob - I am using a 1.8k burst disc, and it does scare the heck outta you! As for the tolerances, I remember reading awhile back how 1600 psi is max for a 1.8k disc. No problem there, but why would one blow when output was (originally) 1500 psi? And just so there is no confusion, when I decided to get into HPA, I bought a 0-3500 psi glycerine filled gauge to check pressures once I was finished screwing with them. When I purchased the bottle (set at 1500), it actually registered just a hair under 1500psi. After installing rebuild kit, pressure read dead on 1600. Both times the disc let go there was roughly 2000-2400 psi left in bottle. Bottle and guns are all in the basement (nice and cool, no direct sunlight). I admit I'm a little dazzled as to why it would fail after 4-5 fills... Would you not think if it was going to blow the disc it would have done it on the first fill?

    @ Eric: I've seen (and saved) that shim/disc spring configuration that Bob posted about. When installing rebuild kit, I made sure disc springs were transferred over in the same order/configuration, so that shouldn't be an issue. I can't see the shims making much of a difference as they are perfectly flat, but just in case it does matter (in order from bottle to reg) - one thick shim (.020"), then 2 thin shims (.005").

    The overlapping between burst disc and regulator makes sense, so I'm thinking I will adjust reg to 1550 psi just to be safe, replace burst disc (I knew I bought a few of them for a reason!) and try again. If it blows again I may end up getting another reg and start fresh.
    Thanks for the help/tips, guys.

    Isn't learning fun?....

    Todd
    Last edited by sholo; Jul 02 2012 at 10:56 AM.
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  7. #7
    Moderator rsterne's Avatar
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    There definitely seems to be a tolerance on the burst discs.... I replaced one on a 1600 psi reg and it's been used for 2 years now with no further issues.... I have read that continually running the tank down below the regulator setpoint (or having a leaking gun) "exercises" the disc and can fatigue it.... I would think this also occurs on a gun like the QB79 where the volume between the regulator and the valve is relatively small, so the pressure fluctuation per shot is quite large.... Perhaps eventual failure is pretty much a given if we push the discs too close to their rating?.... I've seen 1200 psi recommended as a limit for a 1.8K disc (Tim@Mac1)....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  8. #8
    Senior Member SeanMP's Avatar
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    I would be looking at the hard seat in the body.

    When I have a high pressure regulator start acting funny and blowing the safeties randomly....(always at 2am I might add) it's an issue at the seat.

    Imagine a receiver 14' long 3 ' in diameter containing 450psi dumping through a 2" safety valve.....no bloody wonder I was grey at 35.

    If you can hook your hose to the output side with your gauge hooked to the hose and the valve open. watch it for a couple days for slow creep....I you want a calibrated test gauge I just happen to have one I'd be happy to loan ya
    Sean

  9. #9
    Senior Member sholo's Avatar
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    Thanks for the tip, Sean! I will try your idea regarding 'creep' and see what comes of it.

    Just to clarify (please excuse my ignorance ) - when you say "hard seat in the body", do you mean the part of the bonnet where the shims are located between plunger and bottle?

    Thank you for the offer (I do appreciate it!), but the gauge I have goes from 0-3500 psi in 50 psi increments, which is attached to a remote coil hose assembly I purchased from Eric. Not a very fancy or hi-tech setup, but should serve the purpose, no? Or would I need something more precise?

    Thanks again, sooner or later I will get the hang of it!

    Todd
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  10. #10
    Administrator AirGunEric's Avatar
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    What constitutes a typical "issue at the seat"- i.e. crap buildup (sure, take that any way you like- just don't tell us if you soiled yourself) or some sort of wear?
    I'd say I care- but I'd probably be lying...


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