J-Valve on vintage twinset.

[Scuba Lawyer]

Does look like 50's (especially if 2250 psi). Also looks like it has a Sportsways-type 1/2" straight thread o-ring sealed neck, at least from the angle shown. Even though heavy on land, you might find those tanks a bit "floaty" in the water, at least a set I used one time were (although I recall those were 42's at 1800 psi). YMMV. Lastly, and this is just me, if you plan on using a double hose regulator with those tanks I'd flip the yoke so it is pointing down rather than up. That way the reg is lower and better positioned on your back for optimum breathing. My unsolicited 2psi.

Great looking tanks by the way.

 

[James79]

Last point: when filling the tank, remenber that the reserve rod must be pulled down. If not, there is the risk that one of two cylinders is not filled.
The tank looks full, but if you pull down the rod, the pressure will equalize and you suddenly discover that the tank is just half filled.
Nowadays most shops are not used anymore to these old valves, so be sure of instructing them properly when you give them the tank for being filled.
And when you get the tank back, check the pressure both before and after pulling the reserve.

THIS... definitely this!

 

[Angelo Farina]

Lastly, and this is just me, if you plan on using a double hose regulator with those tanks I'd flip the yoke so it is pointing down rather than up. That way the reg is lower and better positioned on your back for optimum breathing

Absolutely true. The manifold is tilted upside down. Which also means that the reserve is actually on the RIGHT tank, as I did always see on all twinsets...

 

[Ghost95]

No worries... with an unbalanced first stage (flow by pistons are about the only ones now) the IP fluctuation over tank pressure is more pronounced (maybe 20-25 psi)... but not enought that I would isolate that 75 to 100 psi in one tank and loose access to it. Particularly when J-valve diving (vintage, no spg style) is generally predicated on "when you hit the reserve it's time to surface".
Regarding weighting, I don't know what you normally use... but when I went to single old school 72s from AL80s, I dropped 5 lb off my belt.
If you decide you don't like them, let me know... I might make you an offer!
Respectfully,
James

Thanks, I got these as part of a package deal on craigs list with a all original DAAM that had not been opened since it was built. Pictures of the inside of that are on another post.

Anyway, when I finish rebuilding that regulator I plan to dive it with these tanks. I'm looking forward to going out to our local training spot and watch the students in all their silly gear stare as I go by. Think I need a BFK too. Wondering where I can get a pair of Mike Nelson style shorts.

 

[Scuba Lawyer]

Get a Sea Hunt vintage harness from my buddy Allan at Vintage Scuba Stuff! A&D Adventures Products

 

[Ghost95]

Does look like 50's (especially if 2250 psi). Also looks like it has a Sportsways-type 1/2" straight thread o-ring sealed neck, at least from the angle shown. Even though heavy on land, you might find those tanks a bit "floaty" in the water, at least a set I used one time were (although I recall those were 42's at 1800 psi). YMMV. Lastly, and this is just me, if you plan on using a double hose regulator with those tanks I'd flip the yoke so it is pointing down rather than up. That way the reg is lower and better positioned on your back for optimum breathing. My unsolicited 2psi.

Great looking tanks by the way.

Thanks for the input. I'm familiar with "J" valves but I have never had doubles and wasn't quite sure how that system worked with 2 tanks 100%. It would be a surprise to only have them get half filled but I'm sure it happened quite a bit as "K" valves became the norm and tank monkeys didn't know how to operate them. I might have made that mistake as a tank monkey once or twice years ago filling singles, or rather trying to understand why a customer would want me to fill a full tank...I only had to look dumb a couple times to remember to check the valve.

Also, the manifold can be easily rotated and the outlet rotates smoothly so thanks for the tip on flipping it over. I'll do that when I get the setup ready to dive.

 

[Ghost95]

Does look like 50's (especially if 2250 psi). Also looks like it has a Sportsways-type 1/2" straight thread o-ring sealed neck, at least from the angle shown. Even though heavy on land, you might find those tanks a bit "floaty" in the water, at least a set I used one time were (although I recall those were 42's at 1800 psi). YMMV. Lastly, and this is just me, if you plan on using a double hose regulator with those tanks I'd flip the yoke so it is pointing down rather than up. That way the reg is lower and better positioned on your back for optimum breathing. My unsolicited 2psi.

Great looking tanks by the way.

You are right about the 1/2" valves. They are a White Stag manifold though, not Sportsways I have a single with a Sportsways 1/2" valve too.

 

[Sam Miller III]

year the tanks were produced
aka markings on the necks

 

[Luis H]

Like @Scuba Lawyer mentioned, those White Stag cylinders used the same 1/2” O-ring seal neck threads as the Sportways.

If I recall correctly you can loosen the nut on the center post and either rotate the outlet, or you can remove the nut, pull up the center outlet and re-insert it from the bottom, so that the outlet is lower. You do not have to mess with the cross bar. And you can do all this with full tanks with the valves closed. The center cross bar holds no pressure if the valves are closed (and there no regulator attached).

All the joints in this manifold are O-ring seal and you can easily adjust the valve to valve distance by rotating the center cross bar. It works like a turn buckle (or bottle screw, as the Britt’s would call it).

Again, this is how I remember it, but I don’t always trust my memory.


The reserve only holds back pressure in the one cylinder. When you open the reserve the cylinders will equalize if both valves are open.


With this style of valves you can also monitor your air by using the decanting method and use the rule of half’s. The methodology is to dive with one cylinder open and one closed. When it gets hard to breathe you know you have used half your air. You then open the cylinders to equalize the pressure and then close it again, until it gets hard to breathe again.

Every-time it gets hard to breathe and you equalize the cylinders you know you just used about half of the gas you had. If you keep track of how many times you do it you can safely monitor your remaining air. In practicality you can only repeat the decanting process 2 or 3 times (max) with cylinders this small, but if you are diligent about decanting, closing the valve, and counting the number of times you have decanted, you can keep track of your air consumption without an SPG or in zero visibility water (this method has been use for zero visibility water).

It practicality the first half way point is your return signal, with a lot more gas to return underwater, as opposed to the reserve, which only give you enough gas to go up to the surface. And then you need to swim home on the surface.

 

[Ghost95]

year the tanks were produced
aka markings on the necks

I don't have a good picture, and the tanks are not with me now, but as I remember the original hydro was in the early 60's. The oldest hydro I see in the photos I do have is 4L69. If I remember correctly there were 2 previous hydro dates and 63 is sticking in my mind as the oldest for some reason.

These are ICC marked tanks so pre DOT time frame.

Looking forward to playing with them.