• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Valve help: converting old LP72s to modern doubles

Discussion in 'Vintage Equipment Diving' started by Jake, Aug 27, 2020.

  1. Jake

    Jake ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: CA
    465
    69
    28
    Hi all-

    I've been on the hunt for a set of LP steel 72s since I hate humping my twin 100s up and down the California cliffs. I finally found a clean set on Craigslist; they have a vintage J-valve setup on them with a single regulator manifold. I believe it was previously used with a double hose regulator set. Both the tanks and the manifold are branded with Sportways (RIP).

    I tried to find specs for this specific tank online but didn't have any luck. So, I broke the set apart and took off one of the valves. The valve diameter seems to measure 3/4" but I'm not sure about the thread size. I took a gamble and ordered a 3/4" manifold set from DGX but I'm not certain they'll fit. The earliest hydro date I can find on them is from 1991; if the tanks were made in the 80s maybe they are modern standard.

    Would anyone here know what I might be looking at, and whether it's possible to get a standard DIN valve set attached (assuming the DGX one won't work)?

    Pictures of the valves are attached. (Please ignore any dog hair. My corgi converts 100% of her nutrient intake into hair she can shed and I don't always notice it .)

    IMG_6268.jpg
    IMG_6269.jpg
     
  2. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    14,688
    15,869
    113
    they should be "modern" 3/4-14 thread.... The problem you will have is the diameter of the tanks is not 7.25 inch or 8-inch which are the modern tank diameters (actually, there are now 6.9" modern LP tanks creeping into the fold again). The vintage 72 is 6.9". Modern bands are available in 6.9 diameter, but not at all easy to find (low-to-no stock). Traditional manifolds are on different spacing, and so vintage bands will not work with modern manifolds (nor the opposite).

    Putting a vintage LP72 set together for modern use is always a bit of fun.....
     
    Jake likes this.
  3. James79

    James79 Reinventor of Wheels ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Lower Alabama
    740
    925
    93
    I hate to disagree with @rhwestfall , but that looks like the Sportsways 1/2 NPS that they did for a while. Pipe thread sizes are based on inside diameter of the pipe, so modern 3/4-14 NPS measures just over 1 inch actual. I have one old Sportsways 72 with the 1/2 NPS valve... If I lived out west I'd probably trade you for a couple of my 3/4-14 72s, but alas, I do not.

    Respectfully,

    James
     
    captain, Sam Miller III and Jake like this.
  4. Jake

    Jake ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: CA
    465
    69
    28
    Thank you very much for the reply. This gives me hope. :)

    The description on the DGX 7.25" bands says they fit 7" and 6.9":

    The 7.25-inch bands and bolts also fit the 7.0-inch diameter LP85's and the 6.9-inch diameter AL72's, with the bolt height adjustment depending on the depth of the "V" in the backplate. The adjustable height bolts in the 7.25 bands and bolts kit will work fine on these slightly narrower cylinders.

    So, I'm keeping my fingers crossed on those too.
     
  5. Jake

    Jake ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: CA
    465
    69
    28
    So, should I be looking at a valve like the XS Scuba 1/2"?

    XS Scuba Pro Valve with 1/2

    If so, I wonder if they make those in right/left hand configurations to accept a manifold.

    I note that the XS Scuba valve is rated to 2250 while the tanks are plus-rated to 2500. Guess I'll have to be careful with that.
     
  6. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    14,688
    15,869
    113
    May very well be. Can't see pics clearly on my phone...
     
  7. James79

    James79 Reinventor of Wheels ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Lower Alabama
    740
    925
    93
    Unfortunately the XS Scuba ones are 1/2 NPT (taper thread)... the Sportsways 1/2 NPS (straight thread) are a real oddball. If you really want to put a modern manifold on 1/2 NPS tanks, only real option is to have 3/4-14 valves/manifolds machined down. If I'm right and yours are 1/2 NPS, your easiest option is probably to put out a call for someone local willing to trade you for 3/4-14 thread 72s.

    Regarding valve rating, that is really just the installed burst disc rating. Which should match the tank's working pressure (not the + rated pressure). So a steel 72 that's rated for 2250 gets a 2250 burst disc, even if it is + rated and normally filled to 2500. The burst disc doesn't pop till 5/3rds working pressure, so a 2250 burst disc won't pop till approximately 3700 psi. I have a tendency to run my 72s between 2800 and 3000 psi... no issues with the burst disc.

    Respectfully,

    James
     
    rhwestfall and Jake like this.
  8. Jake

    Jake ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: CA
    465
    69
    28
    Thank you both for the replies. I appreciate it!
     
  9. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    14,688
    15,869
    113
    @James79 - I'm so used to seeing Norris and PST 72's, the Healthways completely slipped my mind.....
     
    Jake likes this.
  10. James79

    James79 Reinventor of Wheels ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Lower Alabama
    740
    925
    93
    No worries, just wish I either had better news, or lived close enough to trade you!

    @rhwestfall , I'm just glad to have something useful to contribute!
     
    Jake and rhwestfall like this.

Share This Page