Question Old HP100 Tanks

[DiverMZ]

Hey guys - I have the chance to buy a doubles set of HP100s, Aqualung born in ‘97.

They passed hydro in ‘23 and it’s a pretty decent deal (2 for the price of one new one), but I’m concerned with how many years I’ll realistically get out of them.

Thoughts?

 

[Still Kicking]

Hey guys - I have the chance to buy a doubles set of HP100s, Aqualung born in ‘97.

They passed hydro in ‘23 and it’s a pretty decent deal (2 for the price of one new one), but I’m concerned with how many years I’ll realistically get out of them.

Thoughts?

If cared for, most likely they wil outlive you and everyone reading this.

 

[runsongas]

only potential downside is they are the 7/8 neck 300 bar din and you don't currently run din regs

 

[DiverMZ]

only potential downside is they are the 7/8 neck 300 bar din and you don't currently run din regs

I have DIN regs and I’ve been told they’re PST tanks. How’s the trim with those compared to fabers?

 

[tursiops]

I have DIN regs and I’ve been told they’re PST tanks. How’s the trim with those compared to fabers?

Trim on those tanks is great. Been diving them for 20 years. Bought them used, will probably sell them used some day for the same price or more.

 

[tmassey]

Hey guys - I have the chance to buy a doubles set of HP100s, Aqualung born in ‘97.

I have DIN regs and I’ve been told they’re PST tanks.

HP tanks of that age are most likely PST. You can tell definitively by looking at the markings on the tank: you should see a PST test symbol, and they will say either SP9791 or (more likely) E9791. (Those two are used interchangeably: they stand for “special permit“ and “exemption“.)

Also at that age, they are highly likely to be the narrow 7/8 UNF necks. You can again tell definitively by looking for the pressure level in the markings: you will see either 3442 or 3500. These are highly likely to be the 3500, which are the narrow necks. The wider standard 3/4 NPS are the 3442s.

The biggest difference is that the 3500 tanks require 7/8 UNF valves. Those valves will only be 300 bar DIN — they are not convertible to yoke, nor can you purchase yoke valves for that tank. Single valves are not impossible to find, but not common. Manifolds for doubles are very difficult to find. Theoretically they can be purchased new, but I had absolutely all kinds of problems with that: Blue Steel 7/8 UNF (narrow neck) manifold problems with PST tanks

I can’t speak to the trim difference between those and Faber tanks, seeing as I have never dove Faber HP 100 tanks before. However, the HP 100 PST tanks are quite popular and very much liked by those who dive them.

PST hot dipped galvanized steel tanks are very high-quality tanks. There are ignorant people who, because of completely misunderstanding issues with aluminum tanks from before the 1990s, think that scuba tanks can “get too old“ and need to be disposed of. That’s not true of proper aluminum tanks, and has never been a problem with steels. However, I am seeing more and more ignorant and greedy dive shops lean into that. Of course, they have a vested interest to sell your new scuba tanks….

However, those narrow necks are a hassle. They limit what you can do with them now and in the future. So I personally would not purchase them unless it was at a noticeable discount. If you keep your eyes open you can get standard neck HP 100 somewhat regularly. I personally would go out of my way to avoid acquiring more of them, unless the price is just too good to pass up. Which for me would probably be no more than $100 or so per tank. If I really, really needed the tanks, maybe I would pay $150. But if someone wanted more than that, I would just wait until I could find 3/4 NPS tanks.

 

[Still Kicking]

HP tanks of that age are most likely PST. You can tell definitively by looking at the markings on the tank: you should see a PST test symbol, and they will say either SP9791 or (more likely) E9791. (Those two are used interchangeably: they stand for “special permit“ and “exemption“.)

Also at that age, they are highly likely to be the narrow 7/8 UNF necks. You can again tell definitively by looking for the pressure level in the markings: you will see either 3442 or 3500. These are highly likely to be the 3500, which are the narrow necks. The wider standard 3/4 NPS are the 3442s.

The biggest difference is that the 3500 tanks require 7/8 UNF valves. Those valves will only be 300 bar DIN — they are not convertible to yoke, nor can you purchase yoke valves for that tank. Single valves are not impossible to find, but not common. Manifolds for doubles are very difficult to find. Theoretically they can be purchased new, but I had absolutely all kinds of problems with that: Blue Steel 7/8 UNF (narrow neck) manifold problems with PST tanks

I can’t speak to the trim difference between those and Faber tanks, seeing as I have never dove Faber HP 100 tanks before. However, the HP 100 PST tanks are quite popular and very much liked by those who dive them.

PST hot dipped galvanized steel tanks are very high-quality tanks. There are ignorant people who, because of completely misunderstanding issues with aluminum tanks from before the 1990s, think that scuba tanks can “get too old“ and need to be disposed of. That’s not true of proper aluminum tanks, and has never been a problem with steels. However, I am seeing more and more ignorant and greedy dive shops lean into that. Of course, they have a vested interest to sell your new scuba tanks….

However, those narrow necks are a hassle. They limit what you can do with them now and in the future. So I personally would not purchase them unless it was at a noticeable discount. If you keep your eyes open you can get standard neck HP 100 somewhat regularly. I personally would go out of my way to avoid acquiring more of them, unless the price is just too good to pass up. Which for me would probably be no more than $100 or so per tank. If I really, really needed the tanks, maybe I would pay $150. But if someone wanted more than that, I would just wait until I could find 3/4 NPS tanks.

He said they were already doubled up so no problem on the manifold. Are many people diving doubles with yoke regs these days?

 

[tmassey]

He said they were already doubled up so no problem on the manifold. Are many people diving doubles with yoke regs these days?

Oh, I missed that. Well then: now we get to hear about my other reason for not liking these tanks…

Do they have a Genesis 6300 manifold? Those are the “slant back” valves. That manifold has two negatives. First, they are face-sealed. That arrangement is a little bit more fragile and fussy, and do not allow width adjustment (or they wouldn’t seal). The other, bigger issue is that those manifolds have a 207mm spacing. Modern manifolds are radially sealed with multiple o-rings, and are built to 215mm spacing. What that means is you can’t use modern bands with the Genesis manifolds. The only 207mm bands I’ve ever seen in real life are paper-thin, narrow and are merely tack-welded at the bolts and are easily bent when tightening them.

Plus, the 6300 valve seats are proprietary and not easy to come by. I know of only one source: Sherwood 6300 Valve - Seat

If they do not have a slant-back manifold, then all bets are off. I’ve seen face sealed 207mm, face-sealed 215mm and (*very* rarely) 215mm radial-sealed. You’ll need to show us good photos of the manifold to give you an idea of what it is, as well as careful measurement of the distance between the same point on the two valves.

Now, like @Still Kicking said, this matters a lot less when everything is all assembled and working. Use it as-is, and you should be fine. You know, except for every year when you need to tear everything apart for VIP, and if you have any problems with the valve…

My original point stands. I’m only buying these at a discount to non-narrow-necked tanks. I right now have a set of HP100’s with standard bands and manifold for sale for $650. I wouldn’t pay more than $400 or so for narrow neck tanks doubled.

 

[DiverMZ]

Oh, I missed that. Well then: now we get to hear about my other reason for not liking these tanks…

Do they have a Genesis 6300 manifold? Those are the “slant back” valves. That manifold has two negatives. First, they are face-sealed. That arrangement is a little bit more fragile and fussy, and do not allow width adjustment (or they wouldn’t seal). The other, bigger issue is that those manifolds have a 207mm spacing. Modern manifolds are radially sealed with multiple o-rings, and are built to 215mm spacing. What that means is you can’t use modern bands with the Genesis manifolds. The only 207mm bands I’ve ever seen in real life are paper-thin, narrow and are merely tack-welded at the bolts and are easily bent when tightening them.

Plus, the 6300 valve seats are proprietary and not easy to come by. I know of only one source: Sherwood 6300 Valve - Seat

If they do not have a slant-back manifold, then all bets are off. I’ve seen face sealed 207mm, face-sealed 215mm and (*very* rarely) 215mm radial-sealed. You’ll need to show us good photos of the manifold to give you an idea of what it is, as well as careful measurement of the distance between the same point on the two valves.

Now, like @Still Kicking said, this matters a lot less when everything is all assembled and working. Use it as-is, and you should be fine. You know, except for every year when you need to tear everything apart for VIP, and if you have any problems with the valve…

My original point stands. I’m only buying these at a discount to non-narrow-necked tanks. I right now have a set of HP100’s with standard bands and manifold for sale for $650. I wouldn’t pay more than $400 or so for narrow neck tanks doubled.

They have what looks like old dive rite valves and they’re not angled. So I think it’s not a problem? I was planning on splitting them up and then doubling them back up when I move to twinset.