Vintage Double Hose

Looking for a source for new burst discs for my 1800 psi tanks. [1959 USD twin manifold so 3/8" threads?] Using 5/3 of working pressure as a guide it looks like I'd need a 3000 psi disc. So far I have only been able to find 3350 at various on-line places. I looked in Bryan's store but didn't see what I was looking for (if he has them I'd much rather order from VDH). Anyway, all suggestions appreciated.  Mark

discs are supposed to be at test pressure. Unfortunately it is going to be quite hard to find one of those at a normal dive shop. Which valves do you have on them? That will determine whether it's possible or not. Worst case you can just put a higher test pressure disc in there.
You can get most of them here, including 2250 burst discs and he may be able to get 1800's, but if you are adamant about having the right discs you're going to have to let us know which valves you have and then we can help a bit more accurately
http://www.northeastscubasupply.com/bur ... red&page=1

tbone1004 wrote: ↑

Sun Jul 28, 2019 9:40 pm

... if you are adamant about having the right discs you're going to have to let us know which valves you have and then we can help a bit more accurately
http://www.northeastscubasupply.com/bur ... red&page=1

1959 USD NOS 1/2" npt tapered threads. Don't have a pic of the other side currently, but looks like it takes standard 3/8" discs.

Yup, regular old 3/8"

Not So Fast... Check the BLOW pressure
- I got excited looking at that source until I read the descriptions. The 3,000 psi burst disks are "3,000 working pressure, 5000 blow". So, they're for standard 3000 psi tanks, not vintage 1800 psi tanks.
- For my Twin 38s (1800 psi working pressure), I've been ordering the 3360 Burst Disks from DGX... Because that's as low as they go AND, they say "Ratings are release pressure, not service pressure". Here's my thinking:
- If you figure an 1800 psi tank is okay for 10% overfill... We're almost talking about a 1980 psi working pressure. 5/3rds of that is 3300 psi. So, if you can't find any 3000 psi "blow" disks, 3360 is at least in the ball park. Here's the link for DGX Burst Disks:
https://www.divegearexpress.com/prd-saf ... t-disk-kit

-Of course if we can find Burst Disks that blow at 3000 psi, that's what we should use. But I can't find any so I use the next best thing.

Two Ways Burst Disks are Specified
1. Some are sold by the "working Pressure" of the tanks (3000 psi and 2250 psi) . NE Supply
2. Some are sold by the "Blow Pressure" of the Burst Disk (3360 psi and 4000 psi). DGX
- If "blow" or "release" is not in the description, you can't know what you're buying.

P.S. I did a lot of looking around a few years ago. There are 1800 psi tanks everywhere an d there should be burst disks for them. Fire Extinguishers for example. I could not get them through fire extinguisher companies nor extinguisher service companies. I also looked into Paintball... And I found 1800 psi burst disks and a lot of others... But when I got them, the ends had the same threads but were made for different sealing systems... They wouldn't work and could not be made to work. My DGX 3360 "Blow" disks are what I settled on and I'm happy to have a definite answer and rationale.

Rob at The Scuba Museum has burst discs.

SurfLung wrote: ↑

Mon Jul 29, 2019 11:16 am

Not So Fast... Check the BLOW pressure
Here's my thinking: - If you figure an 1800 psi tank is okay for 10% overfill... We're almost talking about a 1980 psi working pressure. 5/3rds of that is 3300 psi. So, if you can't find any 3000 psi "blow" disks, 3360 is at least in the ball park.

Ok, Eben, that's just weird in that I went through the EXACT same mental calculus last night and reached the same conclusion.

Mark

simonbeans wrote: ↑

Mon Jul 29, 2019 11:25 am

Rob at The Scuba Museum has burst discs.

Thanks Allan,

I've emailed Rob to see if his 3000psi discs are working pressure or release pressure. Mark

ScubaLawyer wrote: ↑

Mon Jul 29, 2019 1:15 pm

simonbeans wrote: ↑

Mon Jul 29, 2019 11:25 am

Rob at The Scuba Museum has burst discs.

Thanks Allan,

I've emailed Rob to see if his 3000psi discs are working pressure or release pressure. Mark

Per Rob, they are 3000 psi working pressure so back to the drawing board. Thanks for your input. Appreciated. Mark

I have a couple in stock.

kgehring wrote: ↑

Tue Jul 30, 2019 6:31 am

I have a couple in stock.

Email sent to my SHF dive buddy!

Thanks to Karl I am back in business!