QB79 on 13 CI HPA - Safety?

I'm looking into putting a 13Ci 200bar bottle regulated down to 900 PSI on to a QB79 (XS79 in UK). The bottle has the usual burst/rupture disk on both the high and low pressure sides.

But it the reg fails + the burst disk fails there is the potential to pressurize the rifle to something approaching 200 Bar.

• Has anybody had a genuine safety issue with this sort of combination?
• Is there anyway to add a second burst disk?
• Any other safety features that can be included in the build?

I was thinking of another "O" ring at the inlet end of the valve and a burst nut through the main tube into the into the sidewall of the valve. Doing this would have the advantages of an independent burst disk and extra pinning for the valve, do you think it would work?


Regards Ora

[ribbonstone]

Believe it's a sqafe conversion, if limited to 850-90psi.  Know co2 can get to a higher pressure than that, but limiting HPA to about nthat pressure gives a bit of a safety factor...and you'll still get a good increase from c02 vel.

Add wahtever safey systems you care to.  Personally, drilling and tapping the gas tube for an 18K bust disck seems a cautious step, but if it geives you peace of mind it's worth the doing.

[howie1a]

In scuba tanks if the burst disk fails it emptys the tank the burst disk is between the reg and the tank so it is first in line it's part of the valve I don't know what would happen if the reg failed but the burst disk is your safety I don't see any problem in the burst disk.howie

[howie1a]

In thinking it over I had a co2 paint ball tank I used for a different job and it had a 1800 psi burst disk in it . If you remove the burst disk unit you can see a number on the burst disk it will be the pressure it is rated for , I would think if it is possible to put a second burst disk in line between the tank reg. and the gun you would be able to have a extra safety to keep the pressure from getting to high in the gun. You might check with a gas ( welding shop supplyer ) or a scuba shop to see if you can get a lower pressure burst disk to set up the psi you want for your safety limit. howie, this is just how I see it i'm not a tech, but am a diver.

[howie1a]

I'm new at this co2 stuff but I just read that co2 when it goes from liquid to gas it is about 800 psi and because of this it doesn't need a reg. the co2 is it's own reg. But if you are using air  you will have 3000 psi in the tank and will need a reg to adjust the pressure and any failure of the reg like a hi pressure seat failure you could have the whole amount  of psi left in your tank go in the gun if you don't have a back up safety. In a scuba tankif the a hi pressure seat fails it  will push the low pressure seat off the second stage ( the part you breath from ) until the pressure drops and it will reseat itself for a short time till the pressure builds again. howie

I've ordered a replacement main tube for the 79 from Jack Haley that will take the pressure if the reg fails.


Regards            Ora