2250 burst discs to fit 60s sportsways 1/2" straight threaded valves

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DDKL

Contributor
Messages
144
Reaction score
17
Location
TX
# of dives
500 - 999
I've picked up a couple of the sportsways steel 72s with 1/2" straight threaded valves (the ones with metal knobs). I'd like to replace the burst discs but my LDS has told me they haven't been able to source any 2250 discs or assemblys for a while.

Does anyone know what the specs are for these valves (threads / disc size) and have a good source?

I also have a few slightly newer steel 72s that I need new discs for (they're at hydro right now). If I post some pics would someone be able to recommend a source for new discs or assemblys that would be compatible and the correct (2250) burst pressure.
 
Are you just needing the metal discs or do you need the nylon/plastic washers and/or metal plugs as well?
Many of the old straight thread valves burst discs had a single hole originally. They have most likely been changed to the 3 hole ones over the years. If not you should change them.
Some newer valves had complete assembles that included all 3 parts.
I have some in stock here in Canada that we could work out a price.
Make of valve or pictures might help identify the assemblies you need.
 
I'd like to get a couple of plug/disc/washer sets as I'll change them out next inspection.

They're sportsway branded 1/2 inch straight thread valves with the metal knob. One is a J, one is a K.

They're out for hydro right now but I'll get some photos when they come back.

Getting 2250 discs seems to be getting more difficult according to my LDS.

I think they have been changed to 3 hole plugs as they were able to be sent for hydro/vip without having to replace the plugs/discs.

I'd also like to get some spares that will fit my other 2250 tanks as they need to be replaced as well.

Thanks,

D.

Are you just needing the metal discs or do you need the nylon/plastic washers and/or metal plugs as well?
Many of the old straight thread valves burst discs had a single hole originally. They have most likely been changed to the 3 hole ones over the years. If not you should change them.
Some newer valves had complete assembles that included all 3 parts.
I have some in stock here in Canada that we could work out a price.
Make of valve or pictures might help identify the assemblies you need.
 
Don't worry about the valve. Measure the burst disc plug itself.
 
Thanks. I've only owned tanks in countries where burst discs aren't used so it's a new thing to get used to.

I don't want to pull the plugs until I have replacement discs in hand... Is there an easy way to tell whether it's 3 pieces or a single assembly without removing it?
 
I had some Sportsways valves of that vintage. They are probably M18, not 1/2".

In any case, they take standard burst discs, same as modern Thermo, Dive Rite, DGX, most others except Sherwood. There are three "eras" in burst discs:
- Original 60s/70s burst disc assemblies were in 3 pieces, and the outside piece had a single hole and was installed with a slotted screwdriver. These can be dramatic when they blow, because the jet of air usually knocks the cylinder over, but they have the advantage of being flush with the valve body.
- Later burst discs were still 3 pieces but had the hex head with the 3 vents
- There's a switch underway to one-piece assemblies, which have the advantage of being marked on the outside with the pressure rating, and no way to mix up the disc with the wrong plug, so that you can look at an installed assembly and be certain of its pressure rating.

The first two styles take the same discs and washers.

The problem is that the correct pressure rating to use is 3750, and it's been discontinued by whoever actually manufactures these things. A few dealers still have stock in inventory, and I just picked up the last few 1-piece 3750s at a local shop. 3360 and 4000 PSI rated discs are still manufactured, but aren't really suitable.

contact John at Northeast Scuba Supply. They will have what you need

Their web site shows only Sherwood 3750s.
 
https://www.shearwater.com/products/swift/

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