72 cu ft tank

[rescue15]

I have the opportunity to get a really good deal on a 72 cu ft lp steel bottle. What does everybody think about using a 72 to dive in the 100 to 150 ft range? I am using an 80 now with a 19 cu ft pony. Do you think I'll miss the extra 8 cu feet? Should I hold out for a steel 80?
Thanks,

Steve

 

[LeadTurn_SD]

1. A steel 72 only holds it's full 72 cu ft if filled to the "+" rated pressure. Is the tank still "+" rated as of it's last hydro?

2. An old "Rule of Thumb" is that you should not dive deeper than the capacity of your tank... i.e., don't go below 80' with an Al80, etc...in fact, your Al80 is actually 77.4 cu ft at 3,000 lbs, not 80...

It's actually not a bad rule to follow for safety reasons (to make sure you have enough gas in an air-share situation to get you and a stressed buddy to the surface).

Good explanations are provided in an excellent dicussion about Rock Bottom gas planning here : Rock Bottom and Gas Management for Recreational Divers

Good luck and Safe Diving!

 

[24940]

I used to do dives to 150+ on a steel 72, but I was young and ignorant. I might consider doing such a profile again if I can get my SCR under .2.

Seriously bad idea.

I have the opportunity to get a really good deal on a 72 cu ft lp steel bottle. What does everybody think about using a 72 to dive in the 100 to 150 ft range? I am using an 80 now with a 19 cu ft pony. Do you think I'll miss the extra 8 cu feet? Should I hold out for a steel 80?
Thanks,

Steve

 

[Scared Silly]

Double them up and then they would be perfect for that range. Although then you have a whole new ball game to play ...

 

[spectrum]

I have the opportunity to get a really good deal on a 72 cu ft lp steel bottle. What does everybody think about using a 72 to dive in the 100 to 150 ft range? I am using an 80 now with a 19 cu ft pony. Do you think I'll miss the extra 8 cu feet? Should I hold out for a steel 80?
Thanks,

Steve

They are great tanks

They are not appropriate for the dives you describe unless you double them, or sling a second

Unless they have the + on the current hydro they are more like 65 CF unless you can play the cave country card and that's not likely in MD.

If you are making those dives you should know better. What sort of gas plan do you have for going to 150 feet?

Pete

 

[captndale]

I have several sets of double 72's that I dive in that depth range. You are better off doubling them up than diving a single tank with a pony.

 

[Gilldiver]

As everyone so far has only talked about tank size, perhaps you should think about tank type and condition?

Does it have pipe threads or do they take a standard valve?
Is it in hydro?
Have you had a look inside, is it clean and does it have the resin coating?

An in hydro tank that is clean without the resin, and taking a standard valve is worth about $50 to $75.

If it is out of hydro, has more then flash rust inside, or has a pipe thread - maybe $25 to $50

If it has significant rust and/or has the resin coating - take it for free and make a bell out of it.

I would also check to see if you dive shop will fill "old" tanks. Some will no longer fill any tank older then 1990, even steels. Thay may also not do any tanks with pipe thread valves.

 

[Scubakevdm]

I have the opportunity to get a really good deal on a 72 cu ft lp steel bottle. What does everybody think about using a 72 to dive in the 100 to 150 ft range? I am using an 80 now with a 19 cu ft pony. Do you think I'll miss the extra 8 cu feet? Should I hold out for a steel 80?
Thanks,

Steve

I use mine for an shipboard emergency O2 bottle. I generally take about 235 cu ft to 150, but I tend to stay for a while.

 

[LeadTurn_SD]

I used to do dives to 150+ on a steel 72, but I was young and ignorant. I might consider doing such a profile again if I can get my SCR under .2.

Seriously bad idea.

Me too

If I tried that today at my age, there is a VERY good chance my SCR would end up being under .2, after the dive that is :11:

To the OP: Stay on the "sunny side" of 70 feet with your single Al80 or steel 72 to be safe.

Safe Diving!

 

[Nemrod]

You know, plus sign or not, most dive shops will fill LP steel 72s to 2,500 psi. I rarely have a problem with that, more often the problem is having them filled to 3,000.

At depths in the 80 foot range a steel LP 72 is an excellent choice as long as you monitor your time and remaining air. The aluminum 80 only has 77 cf and that only when at 3,000, often I tend to wind up with pumped 72s and short fills on 80s. The amount of capacity difference between the two just is often no significant and sometimes is to the advantage of the 72. The 72s make excellent tanks for doubles and for no BC diving as well.

I use 72s often on boats where most have 80s or even 100s, I still often manage first in and last out. A couple of good 72s in your tank arsenal is a good choice.

I have made three trips to the Oriskany, watched people dive it to 140 feet on single 80s, there is nothing about that dive that I could not do on a 72, the FACT is that neither tank is enough for those depths.

N