Author Topic: JDS drop tank adapter?  (Read 1009 times)

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Offline M3ga3t

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JDS drop tank adapter?
« on: April 23, 2017, 06:45:26 AM »
Just wondering if anyone has information on when he will be in stock again? I emailed him but he hasn't replied and I don't really want to hassle him so I figured I'd see if any one else would have an idea.

Offline nervoustrigger

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Re: JDS drop tank adapter?
« Reply #1 on: May 01, 2017, 12:27:49 AM »
AT $80, that part is way overpriced.  Why not get the one from Archer http://www.archerairguns.com/QB79-Tank-Block-Kit-p/aaqb79tckitoldmodel.htm and just drill a hole to pin it to the air tube for safety?  That way you save $40 and get it in a few days.

Offline M3ga3t

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Re: JDS drop tank adapter?
« Reply #2 on: May 01, 2017, 02:33:53 AM »
That is a good idea. I'm just not  sure if I trust altering the integrity of the QB adapter to handle up to 3k psi  ???

I would like my reg at at least 1600 psi so I can't use a 1.8k burst disk, just a 3k one

Offline nervoustrigger

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Re: JDS drop tank adapter?
« Reply #3 on: May 01, 2017, 07:33:19 AM »
The limiting factor isn't the tank block itself as much as it is the proximity of the holes to the end of the tube and of course the quality of fasteners.  Pinning it or adding fasteners further back will significantly improve safety.  It is covered in great depth in this thread on GTA http://www.gatewaytoairguns.org/GTA/index.php?topic=105712

A reply which may be of particular interest is reply #27 from Bob (rsterne) that talks about two grade 12.9 screws (M4 x 0.7) located at least 5mm from the end of the tube to achieve a MSWP of 1600psi.  For more than that, you'd need either more fasteners or larger fasteners.

Regarding the 1.8k burst disks, it sounds like you are familiar with the fact they will often not hold 1500psi.  If you go with a 3k, please be very sure you know everything else in the system can sustain such a high pressure.  It's unfortunate that there isn't anything commercially available that falls between 1.8k and 3000psi so I've made my own diaphragms on occasion to get slightly higher burst pressures.  Some details are here http://www.gatewaytoairguns.org/GTA/index.php?topic=73635.msg705843#msg705843 if you are interested.   I want to reiterate that if you decide to go this route, please test multiple samples to failure for confidence.

Offline M3ga3t

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Re: JDS drop tank adapter?
« Reply #4 on: May 02, 2017, 01:09:23 AM »
Thanks for the detailed reply! I have been researching as much as I can find and this is obviously my first HPA project. I just fell in love with the 22xx/Disco platform and even more so when I read chrony numbers on people's regulated, bottled discos and 22xx's.

I must admit I am not doing any of the machining myself, I leave that up to someone qualified and experienced in this department.

M'y valve is pinned with 10-32 screws and I've filled to 3k psi a few times but isn't needed with my disco valve and hammer/spring. Valve lock.

I will check out those links, thanks. Again I am not capable of any machining myself and wouldn't attempt anything when it comes to HPA.

Offline Trophyhunter49

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Re: JDS drop tank adapter?
« Reply #5 on: May 02, 2017, 05:55:51 AM »
The limiting factor isn't the tank block itself as much as it is the proximity of the holes to the end of the tube and of course the quality of fasteners.  Pinning it or adding fasteners further back will significantly improve safety.  It is covered in great depth in this thread on GTA http://www.gatewaytoairguns.org/GTA/index.php?topic=105712

A reply which may be of particular interest is reply #27 from Bob (rsterne) that talks about two grade 12.9 screws (M4 x 0.7) located at least 5mm from the end of the tube to achieve a MSWP of 1600psi.  For more than that, you'd need either more fasteners or larger fasteners.

Regarding the 1.8k burst disks, it sounds like you are familiar with the fact they will often not hold 1500psi.  If you go with a 3k, please be very sure you know everything else in the system can sustain such a high pressure.  It's unfortunate that there isn't anything commercially available that falls between 1.8k and 3000psi so I've made my own diaphragms on occasion to get slightly higher burst pressures.  Some details are here http://www.gatewaytoairguns.org/GTA/index.php?topic=73635.msg705843#msg705843 if you are interested.   I want to reiterate that if you decide to go this route, please test multiple samples to failure for confidence.
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