Steel 72s -- Tell us EVERYTHING you know

[stretchthepenn]

My dive buddy and I know a guy who's looking to sell some steel 72 tanks, and we're considering buying some, particularly for dilout use with our Choptimas. But then we started thinking about it and now we're unsure if they'd be a good investment. Thus, we figured that querying The Hive Mind might help guide our decision.

• How do steel 72s match up against LP85s for SM?
• How does a steel 72 twinset match up against an AL80 twinset?
• Would a steel 72 twinset be a good idea for Tx?
• Would steel 72s in SM be a good idea for Tx?

Any other thoughts? Like the thread title sez, we're interested in hearing everything y'all know about steel 72s, so please chime in.

 

[Invader]

PST MP72s?

What pressures do you get fills at, or what do you fill to?
LP 50s cave filled will blow the MP72s out.

72s are way more negative than 85s. 7.5 lbs per tank more.
Chops are tail heavy already, and the added tank weight in the same area could dip your knees down.

 

[stretchthepenn]

PST MP72s?

Dunno for sure about the manufacturer(s). Will have to check on that.

What pressures do you get fills at, or what do you fill to?
LP 50s cave filled will blow the MP72s out.

The 72s are rated at 2250, IIRC, so air fills would probably be ~3K or a bit less. We'd probably self-fill the tanks with Tx, though, so IDK the likely pressure offhand.

By "blow out" do you mean "outperform" or "detonate"?

72s are way more negative than 85s. 7.5 lbs per tank more.
Chops are tail heavy already, and the added tank weight in the same area could dip your knees down.

Sounds like 72s might not be optimal for SM, then... But would Tx significantly alter the equation?

 

[Invader]

Blow out - outperform.
Tx won't give you that much positive for that size.
Check the neck stamps. What is the stated fill pressure on the tanks. PST would be 3000, i.e. MP tanks.
LP would be 2400/2640(+).
I would SM 85s or BM 50s/85s.

 

[rx7diver]

My dive buddy and I know a guy who's looking to sell some steel 72 tanks, and we're considering buying some, particularly for dilout use with our Choptimas. But then we started thinking about it and now we're unsure if they'd be a good investment. Thus, we figured that querying The Hive Mind might help guide our decision.

• How do steel 72s match up against LP85s for SM?
• How does a steel 72 twinset match up against an AL80 twinset?
• Would a steel 72 twinset be a good idea for Tx?
• Would steel 72s in SM be a good idea for Tx?

Any other thoughts? Like the thread title sez, we're interested in hearing everything y'all know about steel 72s, so please chime in.

I have a thread (Question - Question for Experienced O2ptima CM Divers) from last year, where I consider, in posts #20, #22 and #45, using old-school steel (PST) 72's with a Choptima eCCR (or a Triton mCCR).

rx7diver

 

[James79]

I can't speak to your specific use case, but I dive old school 72s exclusively (which is what you are looking at with the 2250 service pressure). There are a couple manufacturers, but they all have the same characteristics. They are roughly neutral when completely empty, about 6lb negative full. I usually run mine at 2800 psi, making them a true 80cf fill... I'm not a fan of running them above 3k, but they are 3AA tanks (and we know cave divers often run 3AA tanks at test pressure). Dry weight is just a bit lighter than an AL80.

Respectfully,

James

 

[Eric Sedletzky]

I have eight of them.
They make wonderful little shore diving tanks.
Not too heavy, enough air for a 45 minute scouting dive in 45 fsw.
And the best part is most of them were free, and I’ve never had one fail hydro.
I have a few from the mid 60’s.
I will never turn down a steel 72 if offered one, unless it’s 1/2” NPT, then I pass.

 

[Gone for diving]

Love my steel 72 doubles.
Full 7mm suit and glove/hood.
No weight needed,
Dry suit. add 12lb weight belt

 

[PR_SMITH]

Love steel 72's for Sm, very cheap to buy, always pass hydro. My oldest is a '61