Question about my new steel tank (new to me).

[rnln]

Hi everyone,
First of, I am new to scuba and never own a tank. Recently, I acquired an old steel tank from a nice gentlemen. According to him, he had this tank full of air in the garage for 20 year unused. There are still tapes sealed around the valve port (you can see in pictures below). I crank the valve open a bit. There is still pressurized air comes out steadily.

I have searched and read about this tank on this board, and see that it is a longer version of the 72 steel tank. 7" width, 28.5" long. Since I am new, I will have many silly questions, hope you don't mind. Here are some of my first thought.

My first question is... I just done rebuilding my regulators. Can I use the remaining air in this tank to test and adjust my regulators or if the air in there might not be clean?

My second question is if this tank is good enough for me, sure that I am an air hunger since I am new. My instructor commented that the way I breath, I will empty the tank quick.

Another question is if it worth it to bring this tank back to life? The renting rate around here is $12 per day. The first thing I can see is that I have to hydro it, service or replace the valve, and maybe tumble it too.

BTW, what the valve, which has a lever on the side of the tank, is for? It said UP ready to dive, DOWN in reserve. I tried both positions and air seam to come out the same.

Thanks in advance.

 

[Compressor]

Hi: The tank is very valuable as it's an older (I think) steel tank. The valve is a J valve. When air pressure gets to around 200 psi, it will become difficult to breath. The valve was used when there were no submersible pressure guages. Today there are a group if divers who still dive these tanks (sea hunt group an example). Most "modern" divers dive with more modern tanks.
The tank needs a VIP and Hydro to assure safety.
New divers use a lot of air. With good buoyancy and trim, your air consumption will decrease.

 

[Scared Silly]

It is an old Steel LP72. Given it is a plus on the first hydro (see the + next to the year 66) it is a "full" 72 cuft at 2475 psi (2250 +10%).

It can be requalified and used, just find a local place. They probably will not give it the the plus rating unless they have the paper work it, which most do not.

Given the condition, a vintage diver might want it.

 

[SandyRobinson]

Nice find. Couple of thoughts.
1. As Compressor noted, you will need a Hydro and a VIP. If possible, try to get someone to look inside before the hydro for rust or pitting. If there is rust, you will need to have the tank tumbled. Rust does not necessarily mean the tank can not be cleaned and put back in service.
2. If you decide to go thru with the hydro and VIP, you need to decide on a valve to use. If the tank takes a standard threaded valve, I would buy a new valve and not worry about the extra parts for the J valve. If the threads are not standard or you want to keep the valve, you will most likely need to get it rebuilt. If so, I would dump the rod.
Note: Last year, I was given 2 USD steel 72s (born 5-1966 like yours). They were basically empty and had flash rust so each tank had to be tumbled, hydroed, VIPed, and I had both valves rebuilt. Total cost was a little over 100 per tank.
3. As noted above, your air consumption will improve. If the hydro has a plus rating, you can fill it to 2475 which holds about 71.2(?)cf. The compares to 78.6 cf in an AL80. A little less but you will have a lighter tank and the tank will be less buoyant than an aluminum which means you can wear less weight.

 

[rnln]

Thanks everyone for the info. I hope you don't mind for some more questions.

- Is there a reason I want to keep the J valve? Since it's will be hard to breath when it's down to 200PSI, should I get rid of it? How hard it it to find another valve to fit it? I remember I have read somewhere in this board that someone point out a new decent valve cost $35. Is this my case too or diff tank diff valve?

- What is the extra portion of the valve and the SS stick for? Is it for pumping to help breathing easier when it's down to 200 PSI?

- Regarding this part from carobinsoniv mentioned above "...you can fill it to 2475 which holds about 71.2(?)cf. The compares to 78.6 cf in an AL80..."
I have read that the normal LP72 is around 24"-25" in length. This tank's length is 28.5". Does that mean it will hold more than 71.2, which also mean it will hold more or less closer to the AL80 tank?

Is the AL80 the one those scuba shops usually have for rent?

Hope people don't get tired of my questions. Thanks again.

 

[aviator8]

Is there a reason I want to keep the J valve? Since it's will be hard to breath when it's down to 200PSI, should I get rid of it? How hard it it to find another valve to fit it? I remember I have read somewhere in this board that someone point out a new decent valve cost $35. Is this my case too or diff tank diff valve?

I think the issue is probably servicing the valve. If it can be serviced it can be used. You may get some odd looks or refusals to fill as J valves are not in common use today. To get a new valve you need to determine the neck thread type, then determine if you want DIN or Yoke. I dont know if that is half in tapered or something else so maybe others can help there

What is the extra portion of the valve and the SS stick for? Is it for pumping to help breathing easier when it's down to 200 PSI?

The valve on the right opens the air supply feed. Internally there is a mechanism that creates a "reserve" of 200 PSI. I think they can be adjusted and were usually set between 200-500PSI. When you pull the rod it opens the left side which releases the reserve. No need to pump it. It is a single pull.

Regarding this part from carobinsoniv mentioned above "...you can fill it to 2475 which holds about 71.2(?)cf. The compares to 78.6 cf in an AL80..."
I have read that the normal LP72 is around 24"-25" in length. This tank's length is 28.5". Does that mean it will hold more than 71.2, which also mean it will hold more or less closer to the AL80 tank?

Every manufacturer has slightly different capacity. the general numbers I hear used are a LP72 will give you a true 72CU Ft and an AL80 will give you 77CU Ft so they are pretty close in volume

Is the AL80 the one those scuba shops usually have for rent?

Yes Al80's are the de-facto standard tank size used almost everywhere.

 

[grf88]

Check in the Vintage Equipment Diving Forum to see if anybody wants to trade you for a more modern tank. The condition and original label may be of interest to someone.

 

[rnln]

Thanks everyone again.

grf88,
Can you please elaborate on what are the differences between the vintage and the modern tank? Is it about the valve and tank size?
Thanks.

 

[lexvil]

Just a touch of reality;
First the LP 72 is an excellent tank and you’ll almost always get a good fill but the reality, this is true for most old dive gear, this is a tank that if you get it free and spend $50 ata shop for a hydro and viz, you can sell it for $40 but if you dive it it’s a great deal.

 

[AfterDark]

They have great buoyance profiles also, I own 4 72's from a range of years starting at 1965 to 1974, 2 I use as doubles. The other 2 are for my DBL hose use with J valves like yours. I'd change it to a K valve and sell the J on Ebay.

If that tank had air and was kept indoors even in a cellar it'll be fine. My oldest 72 1965 sat in my cellar for a full decade. I dove it to empty it, then brought it for hydro no problem.