• Jefferson State Airrifles
  • Air Gun Web - Expert Airgun Reviews
  • Hajimoto Productions
  • Airgun Angie - Backyard Shooting
  • Nielsen Specialty Ammo
  • Dynamic Air Rifles
  • FX Airguns
  • DonnyFL - When silence is a priority
  • Airgun Archery Fun
  • Pyramyd Air
  • Saber Tactical
  • New England Airgun
  • Umarex Airguns
  • Contact us
  • Utah Airguns
  • SEKHMET Airgun Accessories
  • Freedom Gun Targets
  • Evanix Airguns at Airgun Pro Shop
Jefferson State Airrifles
Air Gun Web - Expert Airgun Reviews
Hajimoto Productions
Airgun Angie - Backyard Shooting
Nielsen Specialty Ammo
Dynamic Air Rifles
FX Airguns
DonnyFL - When silence is a priority
Airgun Archery Fun
Pyramyd Air
Saber Tactical
New England Airgun
Umarex Airguns
Contact us
Utah Airguns
SEKHMET Airgun Accessories
Freedom Gun Targets
Evanix Airguns at Airgun Pro Shop


Author Topic: Hatsan with HUMA regulator added. - How much cylinder pressure?  (Read 217 times))

Offline Cableaddict

  • Marksman
  • ***
  • Posts: 468
  • yes
  • Real Name: Allan
I have a .25 cal Flashpup with an internal HUMA regulator installed.

Like most non-regulated pcp's, this gun is limited to 2900 psi.  I assume that has to do with the quality / design of the valve, hammer, etc.

But with the regulator  (Which I currently have set to 180 bar) there's very little in the gun that ever sees anything higher, no matter what pressure I fill the air tube to. Plus the hammer strength has been slightly dialed DOWN, because I've also drilled out my ports a little.

Total shot count is the one really bad thing about a Flashpup, and it's especially bad when tuned for 180 bar & the larger ports.  So if I could significantly increase the tube pressure, that would be unbelievably good.  I might never need a better rifle.

I know of two guys online who have the same mods and are loading to 3200 psi.  So that's known to be safe,  but some more expensive guns with similar aluminum air tubes are rated to 3600 psi (250 bar.) It seems to me I should "probably" be able to go that high, but of course I'm not brave enough to try. (And can't afford a new gun if might gets beaten to death.)
----------------

So -

Does anyone know what the safe pressure limit would be for this setup? Or at least has anyone with a similar rig gone higher than 3200 psi?


Would the aluminum tube itself be a factor?  I'm thinking no, because it's really small @ 165cc.

Would the quality of the HUMA be a limiting factor?  Maybe all the o-rings before and including the regulator itself?

  • USA, NY, Suffern

Offline nervoustrigger

  • GTA Senior Contributor
  • ******
  • Posts: 7797
  • The Grin Reaper
    • My youtube channel
  • Real Name: Jason
Re: Hatsan with HUMA regulator added. - How much cylinder pressure?
« Reply #1 on: March 02, 2021, 10:59:39 AM »
I don’t think anyone here will advise you that it is okay to increase the fill pressure above the manufacturer’s rating.

Even if it were true that the reservoir can safely handle higher pressure, and that they arrived at the rating based on some other factor such as the valve retention, there is still the potential that the regulator may someday fail and pass the full reservoir pressure to the valve and cause a dangerous situation.
  • MS
Conduct yourself so that when a man accuses you of something dishonorable, no one will believe him.
Barrel accurizing guide
My youtube channel
QB79 HPA conversion
2240 HPA conversion
Intro to PCP airguns

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 24747
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: Hatsan with HUMA regulator added. - How much cylinder pressure?
« Reply #2 on: March 02, 2021, 01:09:08 PM »
Do NOT fill a PCP above the manufacturer's MSWP.... While it will undoubtedly be OK once or twice (after all, it will have been tested to significantly higher).... you are increasing the effect of metal fatigue every time you fill it, because the metal stretches a tiny amount.... This repeated stretching reduces the strength of the metal every time you do it, and this metal fatigue is particularly bad on aluminum.... Filling above the MSWP decreases the service life, and the more you exceed that (in this case 2900 psi), the shorter the life of the tube before it fails catastrophically.... Such a failure could be fatal.... There may be other factors as Jason mentioned that could fail before the tube as well.... Just don't overfill....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline Cableaddict

  • Marksman
  • ***
  • Posts: 468
  • yes
  • Real Name: Allan
Re: Hatsan with HUMA regulator added. - How much cylinder pressure?
« Reply #3 on: March 02, 2021, 03:26:45 PM »
Do NOT fill a PCP above the manufacturer's MSWP.... While it will undoubtedly be OK once or twice (after all, it will have been tested to significantly higher).... you are increasing the effect of metal fatigue every time you fill it, because the metal stretches a tiny amount.... This repeated stretching reduces the strength of the metal every time you do it, and this metal fatigue is particularly bad on aluminum.... Filling above the MSWP decreases the service life, and the more you exceed that (in this case 2900 psi), the shorter the life of the tube before it fails catastrophically.... Such a failure could be fatal.... There may be other factors as Jason mentioned that could fail before the tube as well.... Just don't overfill....

Bob

With respect, (and thanks)  I'm not buying this.
Small aluminum buddy bottles are rated to 4500 psi, and even a 03.L bottle is over twive the volume of the Flahpup's tube. There's no way the air tube itself is going to fail at 3600 psi.

As for the regulator,  sure it might be a problem, which is why I'm asking. But HUMA uses the exact same materials for regulators sold for 250 bar guns, so while I am concerned, I expect that it will be OK.  I just need confirmation first.

So that only leaves the o-rings in the air cylinder and fill probe.   Now THOSE, I am a bit worried about.  O-rings can be upgraded, but that fill probe design might not be optimal.  -  But I don't know.  And neither do you guys.   I'm hoping maybe we have a mechanical engineer on these forums, or someone who was crazy enough to just try it, with long-term success.

What I know for sure is that 2 guys on YouTube have been using 3200 psi for several years already,  so IMO that is absolutely safe.
  • USA, NY, Suffern

Offline Cableaddict

  • Marksman
  • ***
  • Posts: 468
  • yes
  • Real Name: Allan
Re: Hatsan with HUMA regulator added. - How much cylinder pressure?
« Reply #4 on: March 02, 2021, 03:31:35 PM »
Even if it were true that the reservoir can safely handle higher pressure, and that they arrived at the rating based on some other factor such as the valve retention, there is still the potential that the regulator may someday fail and pass the full reservoir pressure to the valve and cause a dangerous situation.

That's a valid point.  I've sent a query directly to HUMA,  but who knows if they'll respond.  This is the kind of thing manufacturers tend to avoid, for legal reasons, even if the true answer is "everything will be fine."
---------------------------------------------------


I guess a realted question to ask would be:

How do the manufacturers come up with their max psi ratings?  I mean, why 2900 psi and not 3000?  That's pretty arbitrary, unless there's a specific parameter they are measuring.   Do anyone know?

And over the years, somebody MUST have routinely filled their gun over the rated spec. And that gun probably eventually failed.
So what specific part of the gun failed?
  • USA, NY, Suffern