Sportsways 38s and 1/2" Straight Thread O-Ring Valves

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SurfLung
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Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sat Jan 26, 2013 1:05 pm

- This is a discussion started in the Vintage For Sale category but now that I bought these little tanks, I'm curious about them.
- That 1/2" straight thread O-ring valve is kind of mysterious. Looking at the Sportsways catalogs on VDH, there's no mention of it BUT, all of the pictures look exactly like it. Even though they make a point of stating that all Sportsways valves are either 1/2" pipe thread or 3/4" Straight Thread O-Ring.
- Also, the catalog shows Sportsways 42 cf not 38 cf. But Rob's tanks are marked Sportsways and are 1880 psi. Are the 42s newer, just a little higher pressure and with the newer 3/4" O-Ring Valve?
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Here are images from the 1961 Sportsways Catalog:
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sat Jan 26, 2013 1:17 pm

At one time, I owned 7 sets of the Sportsways, twin 38's [ most comfortable tanks that I have used in 53yrs diving]...all were 1/2" straight thread manifolds, both reserve and non- reserve typs ,all of the twin's were in the 64' to 1968 range. I still have some of the Sportsways. 1/2" straight thread constant reserve valves

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sat Jan 26, 2013 1:48 pm

I just looked up the '64-'67 catalogs... Still no mention of 1/2" O-Ring valves but they introduced a 15/16th valve and the picture looks like what I am always thinking is a 3/4" valve. The pictures of their 3/4" valve still look like 1/2"... What was actually the standard for them? Was their 3/4" actually what we're calling the 1/2" Straight Thread O-Ring?
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sat Jan 26, 2013 10:02 pm

SurfLung wrote:I just looked up the '64-'67 catalogs... Still no mention of 1/2" O-Ring valves but they introduced a 15/16th valve and the picture looks like what I am always thinking is a 3/4" valve. The pictures of their 3/4" valve still look like 1/2"... What was actually the standard for them? Was their 3/4" actually what we're calling the 1/2" Straight Thread O-Ring?


The confusion is understandable, and is caused by the difference in stating pipe measurements versus all other types of threads. Tapered Pipe thread(NPT)sizes refer to the nominal inside diameter (ID)of a given size of pipe, so the actual outside diameter is larger.

That's why a 1/2" pipe thread valve has an outside diameter (OD) of about 3/4" at some point along the taper. To add further to the confusion about NPT, the ID of a pipe can vary considerably from the stated size with different pressure ratings of the pipe, and the OD is always remains the same for all practical purposes. :?

Straight threads are usually rated by the outside diameter, but there is actually a Straight Pipe Thread that is rated like pipe sizing. So when Sportsways referred to their 1/2" threads, those were the tapered pipe thread valves, and when they refered to 3/4" valves they were referring to the straight 0-ring sealed threads of the tank neck ID. When they referred to the 15/16" valves, that was a reference to the ID of the opening of the more modern tanks... not to an actual pipe thread size. That size is what is still used in most Scuba tanks today, and I think they are actually a 3/4" Straight Pipe Thread with an o-ring seal (even though the OD of those threads is well over one inch). Had enough? :shock:

So Sportsways was not using standard conventions when referring to their thread sizes, thus causing a danged lot of confusion. :? :? I hope I got that right, and if not I would be glad to hear corrections.

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 11:20 am

That makes sense... I hope you have it right! :shock:
If every set that Mistral had is 1/2" straight thread, it sounds like the standard rather than an oddity. If I can find a Sportsways twin tank yoke with O-ring straight threads, it should fit these tanks?
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 12:49 pm

The tanks in the picture are 1/2" tapered pipe thread, I can tell by the use of Teflon tape . Most tanks today are either 3/4" straight pipe thread with the o ring seal or a metric thread. The Sportways 1" straight thread with the O ring is the same as would be found on a 1" bolt, not 1" pipe.
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 1:26 pm

captain wrote:The tanks in the picture are 1/2" tapered pipe thread, I can tell by the use of Teflon tape . Most tanks today are either 3/4" straight pipe thread with the o ring seal or a metric thread. The Sportways 1" straight thread with the O ring is the same as would be found on a 1" bolt, not 1" pipe.


Look closer at the photo of the tanks and you will notice that one apparently has tapered pipe thread valve (1/2" NPT) in it (sealed with TFE Tape), and the other appears to have the o-ring sealed straight threaded valve in it. I can't tell from the photo about the actual threads in the tanks because the NPT threads, being the same pitch (14 threads per inch) as the straight threads will actually screw into the neck of a tank with straight pipe threads. This mis-match will actually seal if taped and torqued sufficiently BUT it is not a proper combination, and possibly even not very safe under pressure.

As far as I can remember no other supplier of Scuba tanks of that era used the straight pipe threads of that size. Sportsways was an innovator for its time, and probably used that 1/2" straight pipe thread with oring seal to make assembly/disassembly more convenient. Seems like I even read something to that effect in one of their ads or catalogs from way back when.

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 1:52 pm

SurfLung wrote:That makes sense... I hope you have it right! :shock:
If every set that Mistral had is 1/2" straight thread, it sounds like the standard rather than an oddity. If I can find a Sportsways twin tank yoke with O-ring straight threads, it should fit these tanks?


SurfLung, since you have purchased these tanks you will be able to identify what the threads are by looking above the top thread of each tank. If you see a small groove cut to accommodate an o-ring you have the o-ring seal with straight threads, and that's the valve type you need. If the internal threads of the tank neck come all the way to the very top of the neck, then you will need 1/2" NPT valves. If you have one tank of each type, then the mixed valve set in the photo is actually what you need.

Rob, Why don't we just ask you what you found when disassembling the set... why didn't I think of that sooner?

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 7:40 pm

- Rob DID find that both tanks take a straight thread O-Ring valve. He said some "knob" had put the teflon taped, tapered threaded valve on one side of the twin tank yoke. I'm 56 and we used words like "dumbell" (I think) when refering to a "knob" :lol: .
- Anyway, they are for sure both straight thread O-Ring threaded tanks. Mistral's comments regarding the comfort of these tanks have me thinking to find the right twin tank yoke and restore these to a nice twin tank set. Anybody know where I can get a Sportsways 1/2" straight threaded twin tank yoke in working condition? :idea:
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 10:54 pm

antique diver wrote:
As far as I can remember no other supplier of Scuba tanks of that era used the straight pipe threads of that size. Sportsways was an innovator for its time, and probably used that 1/2" straight pipe thread with oring seal to make assembly/disassembly more convenient. Seems like I even read something to that effect in one of their ads or catalogs from way back when.


White Stag also made some valves and double tank manifolds with the same tank threads. The double tank manifold was very interesting. It has a single outlet in the center, but individual shot off valves on each tank. I thought the design had a lot of good features. I had a set of small doubles with the White Stag manifold and I am looking for some pictures, but I can't find them.


Surflung,
I have a set of double Sportways manifold that I am not using. I think the chrome is in good shape, but it probably needs to be cleaned and serviced.
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 11:06 pm

Here are some pictures of some interesting White Stag valves and manifold. They all use the same threads as the Sportways.


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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Sun Jan 27, 2013 11:19 pm

That's an interesting set of valves that I have never seen. Thanks for the photos.

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Mon Jan 28, 2013 8:03 am

The double manifold is particularly interesting. Since each valve closes each tank independently, the tanks can be separated full; the center portion of the manifold can be serviced also with the tanks full.

You can also use tank as reserve and decant air as you deplete the other tank. That gives positive notice of when you are down by 1/2 of your air supply, then 1/4, then 1/8, etc.

The center portion of the manifold seals with gland style O-rings and the distance between the tanks can be easily adjusted by turning the manifold. One side has left handed threads so the center works like a turnbuckle. The two lock nuts are used to lock the manifold after it is adjusted.

The center post can be installed on the bottom or the top of the manifold (or it can be rotated front or back).

Over all, there was a lot of thought into the design of this manifold and the quality looked very good.


The only reason I got rid of the twin tanks is because I don’t particularly like to deal with small neck tanks. It is very hard to get a wire brush inside to clean any rust, it is also harder to tumble, etc. The O-ring seal makes them a lot more friendlier than the tapered neck, but I personally prefer to avoid the small neck if possible.

My LDS who is also my hydro station didn't have the fitting to hydro this tanks. They could easily purchase one by ordering it from their hydro supply company, but I would have probably had to share on the cost for just my tanks. At the end I didn't think it was worth it.
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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Mon Jan 28, 2013 9:01 am

My first thought was that these valves could be used as you mentioned - with one cylinder as the reserve, and "decanting" as the other cylinder became depleted to a noticeable point. Then repeating the process as needed. It's a great way to dive in the vintage style, with no pressure gauge, and still know fairly accurately how much air you have remaining.

With the outlet in the lower position, as shown, the valve knobs are possibly high enough to reach them fairly well for this proceedure. I have a set of tanks that I enjoy diving in this manner, thanks to learning it from YankDownUnder. :)

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Re: Sportsways 38s and 1/2" Straight Thread O-Ring Valves

Mon Jan 28, 2013 9:06 am

It is surprising that they did not have the fitting to hydo the tanks. I suppose if they mainly hydro scuba tanks they might not have it but any shop that hydros SCBA equipment should have it. I use a Sportsway manifold on a set of PST steel SCBA bottles and it made a nice set of small doubles. They are 2216 psi.

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