Help: 7l valve thread specs

[NamTinker]

To all you guys that use the 300bar 7l cylinders.
I am trying to source a manifold for my twins but the cylinder thread specs are not stamped on the neck.
The valves are Draeger, taper thread.  Looks like ANSI 1/2" x 14.  But, Draeger is European and it should therefore theoretically be a metric thread.
Anybody have the exact specifications?
Any help will be appreciated!

[darthmoll]

why not just go into your local shop tell them what you want and they will know what is required, or should be able to find out.

[Bob Cooper]

What are the markings on the tanks?

Do they have a parallel or tapered thread? (tapered thread will have PTFE tape or similar on them)

If you can relay the tank markings then the thread form in the tank neck can (usually) be fathomed out quite easily.

[NamTinker]

darth: Local shop: If that was so easy!  We have no dive shops in Namibia - everything is imported.  The closest shops (in South Africa) need to know the thread specs to see if what they have will fit.  In fact: the majority of items are so expensive that I imported 80% direct from the UK.

Bob: The thread is tapered - with thread sealing tape.  I'll check the exact markings on Friday - cylinders are now (since the valves are out) also sent for the visual & hydro test.  Will post the markings then.

[Digger]

Are 300bar tapered threads still ok? I suppose the testing requirements will be different in Namibia, but good luck trying to get a manifold for them. You won't find one second hand as far as I know, and there are precious few who sell them (let alone have them in stock) new. If you do find a source of cheap second hand manifolds, let me know, as I'm trying to track down manifolds for tapered thread tanks at the moment.

[lawrence]

you could always get a manifold and have someone cut a new thread on the valves. M 25 treads are certainly bigger than the 5/8bsp .715 tapper valves I've had, but youd have to verify this for your thread size.

[NamTinker]

Digger: testing requirements are the same over here.  It seems the duration validity of the tests vary worlwide.  Hydro over here once every 4 years, visual every year.  And they don't ask your opinion - if condemned, you just receive your cylinder back drilled full of holes! And there is only one testing facility that can even go to 450bar test...
What is the thread specs for straight thread?  Wouldn't M25x2 be too large?  And obviously any re-threading would require re-testing.

Lawrence: The valve thread you mention - is that what you had standard on 7l 300bar valves?

[lawrence]

5/8 x.715 is one of many tapper threads (I couldn't tell you how many or their sizes). If you can imagen a long thin cone with a uniform tapper, divided into, say inch segments along it's length, each segment gives a thread size for that particular taper. So there might be a dozen sizes for any particular tapper. Any test house should have a guage (very much like the cone described above), so can tell you exactly what thread you have. Asuming the diameter was <25mm, you could get an M25 turned down.

Lawrence

[NamTinker]

Bob - for what it's worth: Markings on the tanks: DRUCKLUFT-AG 300bar, 960 V 6 450 8.42, 01D6 80 1WKA 2 574 F 48062

Digger: I have just been informed that there is a company in Germany that sells all these valves, manifolds etc - all tapers, threads, sizes etc.  They also stock a cylinder valve with two taps.  You then do not require an isolation center valve, just a straight bridge pipe - one tap on the valve closes the opening to the other cylinder, the other closes the access to your first stage.  So with any first stage trouble you can isolate the stage without losing the cylinder.  Sounds better than an isolation manifold valve.