Steel 72 Characterisitics

[luis]

Here is a better copy of the table I provided before.
I hope it is easier to read. It shows the buoyancy characteristics for many steel and aluminum tanks.
For the steel 72 (71 in the table) empty = 3.5, full = -2.0.
I don't know if that includes a valve.

I am sorry that the labels on top do not line up with the columns.

Specifications for Selected SCUBA Cylinders


Metal___VOLUME___SERVICE___LENGTH___DIAMETER___EMPTY WT.___BUOYANCY___BUOYANCY
ALLOY___(advertised)___pressure___(in.)___(in.)___(Lbs.)___empty___full
steel___15___3,000___13.8___4.0___7.5___-1.3___-2.5
steel___42___1,800___19.1___.8___20.1___1.4___-1.9
steel___52___2,250___19.4___6.9___22.0___0.0___-4.2
steel___53___2,250___19.1___6.8___20.5___1.4___-2.8
steel___65___2,460___21.4___7.2___28.5___-3.3___-8.2
steel___65___3,500___16.8___7.0___2.40___-1.5___-6.4
steel___71___2,250___25.0___6.8___29.5___3.5___-2.0
steel___71___3,000___20.5___6.8___28.6___-4.6___-10.3
steel___80___2,460___24.0___7.3___31.9___-2.0___-8.0
steel___80___3,500___19.8___7.0___27.0___-1.0___-7.0
steel___94___3,000___25.0___7.0___39.0___-6.0___-13.3
steel___95___2,400___23.8___8.0___37.2___1.5___-6.2
steel___95___2,460___23.8___8.0___38.8___-3.0___-10.1
steel___100___3,500___23.9___7.0___33.0___0.0___-7.4
steel___104___2,400___26.5___7.8___44.0___0.0___-8.2
steel___108___2,400___26.8___8.0___41.0___0.0___-7.0
steel___120___3,500___27.9___7.0___38.0___1.0___-8.0
steel___121___2,400___29.3___8.0___45.0___0.0___-8.0

alum.___13___3,000___12.9___4.4___5.8___1.7___-0.7
alum.___14___2,015___16.5___4.4___5.4___1.4___0.4
alum.___50___3,000___19.0___6.9___21.2___4.4___0.7
alum.___53___3,000___19.6___7.2___28.2___-1.6___-5.6
alum.___60___3,300___19.1___7.2___27.8___-1.6___-6.1
alum.___63___3,000___21.8___7.2___26.6___1.7___-3.0
alum.___67___3,000___23.0___7.2___30.5___0.4___-4.6
alum.___70___3,300___23.0___7.2___32.8___-0.3___-4.9
alum.___71___2,475___28.8___6.9___30.6___10.6___5.2
alum.___72___3,000___26.0___6.9___28.4___2.8___-2.4
alum.___80___3,000___26.1___7.2___33.0___2.2___-3.8
alum.___80___3,000___26.1___7.2___31.5___3.8___-2.1
alum.___80___3,300___24.5___7.2___34.5___0.6___-5.4
alum.___100___3,000___26.6___8.0___40.9___2.5___-5.0

[Ron Hearn]

Canadian guy here. ;D


A hydro test facilities has to be tested and licenced from the same government department so what difference does it make if there's a hydro station in a scuba shop or if the scuba shop sends your tank out to a in dependant facilities that more than likely spends most of there time filling fire extinguishers cause that's were the big money is. Its the facility that gets certified and its the owner who need to perform the on site test for the inspector, this is were I believe some times problems exist. Many hydro stations employ staff and give a few hours of training on the hydro machines than leave them to it leading to all kinds of mistakes down the road for guys with 72 steel tanks.

Ron Hearn

[Captain]

Ok guys, yesterday I got on the DOT site and submited the following queston.

Do personally owned, filled, transported and used 3AA air cylinders required to meet DOT regulations as to requalification(hydro).

I just received a call from them and was told that as long as the cylinders are not used in commerce (meaning the exchange of money for a service or product) they DO NOT fall under DOT regulations.

If anyone would like to talk to DOT the number is 202-366-1289

Now in my opinion in the unlikely event that a cylinder that is not in current hydro fails and injures someone you could be sued in civil court for neglegence but would not be subject to criminal prosecution as no law was broken. Of course you could still be sued even if the tank was in hydro.

[mossback]

HIp Hip Hip Hurray for Both Luis and Tom.......now the dust should settle

[duckbill]

Wow! I just got back from a three day weekend. What gives?! Dove the DAAM in Monterey. Nice dive except for the octopus leaking air (it was there for my buddy in case he needed it ). Thought the IP had gone up, but it was just the second stage of the octo leaking. I know! Just take that blasted thing off. A DAAM doesn't need an octopus anyway. Or, to rephrase that, who needs a DAAM octopus anyway!

Anyhow, James, here are the specs from a site I downloaded. I don't have the URL or I'd give it to you.
+3.5 empty, -2.0 full w. 10% overfill (71.55 cu ft), no valve.
I'll work on finding the URL tonight as it has a very good listing of tanks.

Also, the modern, heavier steel tanks CAN be dived without a BC using a full 7mm wetsuit (very buoyant at SHALLOW depths), just not as safely as a good ole 72. Don't forget about us cold water divers. Other than vintage regulator compatibility, the biggest problem with high pressure tanks is the wide buoyancy swing.

[swimjim]

Okay, as long as this dog won't die. I have one question for tanks in general, including the good ole '72 of which I own three. Does it hurt your tanks to keep a full charge in them over winter? I guess I just want to be ready to go diving if the weather permits, so I usually keep my tanks full. Is there a reason why I should not do that? Thanks.

Jim

[Captain]

I would not keep aluminum tanks pressured up but that is just my own opinion. I see no issue with keeping the steel tanks pressured up. Of course if there is any water in the tank the higher PO2 would increase the rate of corrosion.

[mossback]

steel vs alum....thar's a reason ol Quint got eatten and the sheriff shot at a alum. tank in that sharks mouth instead of steel..............

Peter Benchley, God rest his soul, knew a 30.06 might of steel......but shatter Alum......an the shark

[swimjim]

Thanks Tom and James

jim

[duckbill]

duckbill said:

........here are the specs from a site I downloaded. I don't have the URL or I'd give it to you.
+3.5 empty, -2.0 full w. 10% overfill (71.55 cu ft), no valve.
I'll work on finding the URL tonight as it has a very good listing of tanks.

Here it is: www.diverlink.com/gear/tankspecifications.htm

[Gomez' echo]

I knew somewhere I had the characteristics of the early tanks. This comes from Roberts, Basic Scuba, 2nd ed., p.5.

Hope this helps.
Allan

[JES]

This has been one of the most enjoyable, highly informative, and spirited posts in a while.

Thanks to everyone for sharing all of your collective information. It is truly educational.

[Captain]

Strange, I have had an old tank that hasn't had a valve on it in years and it still only has light flash rust in it.

[duckbill]

Here is a cylinder test I saw on SB once. Try it, it works!
"Place a magnet against the outside surface of the cylinder and let go. If the magnet falls off, the cylinder is defective."

[JES]

duckbill said:

Here is a cylinder test I saw on SB once. Try it, it works!
"Place a magnet against the outside surface of the cylinder and let go. If the magnet falls off, the cylinder is defective."

Now you're going to have everyone thinking that their Aluminum tanks are bad and they'll start dumping them on ebay only to have the paintball guys buy them.