Aliminium or steel tank Which one to buy???

[SeaJay]

Yeah, that's pretty much what I'm thinking, too... I just have to figure out if I can go over to the new "E" series with my new rig. I may have to switch to an aluminum backplate first to do it. Not sure... I'll have to see.

Personally, I think I'm more interested in the PST HP120, which is roughly the same size as an AL80, only slightly heavier, and offers more than 100 cf at low pressure, and 120 + overfill at high pressure.

The only thing that I don't like about this setup are the DIN valves. Despite what many others say, I'm not a fan of DINs. They hold water which can't be blown out... And there's the O-ring issues...

But it'd be a small price to pay if it will work out, weight and trim-wise.

...Gonna play first.

 

[Genesis]

have convertable valves. 232 bar DIN with a yoke insert included.

They "got away" with this by cutting the service pressure by ~50 psi; technically these are 232 bar tanks, which works and is within - just barely - the yoke-allowable range.

I am interested in a couple of HP120s too, but (1) they won't be available for another month or two, and (2) they are a bit taller than the AL80s. I dive with a bunch of guys who have them, and I don't think I'd like them doubled - and since I MAY double a setup in the future, they're no good for that possible use. I've seen 'em a bunch of times right next to my ALs in the racks... the difference is about 2" in length. The 100s are about 2" SHORTER and look a LOT like an AL65!

I can always buy a pair of 120s for single-tank OW diving if it turns out that the 100s are not quite enough gas. I'm the "sipper" of the people I dive with - today was a riot; diving with a bunch of guys with HP120s, me with an AL80, and ScubaScott who was down here (he got nice and wet, but was diving air .vs. my EANx), we're down about the same amount of time and I come up with MORE gas than they have - with them starting out with a 50% supply advantage.... Its pretty wild when you surface with over 1000 psi still in the tank and these guys are in the ~500 psi range.... I was buddying up with Scott today, so we were hitting his NDL long before I ran into either of my turn points.... that's ok, there weren't any shootable fish to be found (it was a nice pair of dives anyway)

 

[SeaJay]

Cool! Yeah, I've seen these before. They're pretty cool, if only because all of your buddies' regs fit your tanks.

Well, that solves that problem... Very cool how they did that!

...Now if the weight's just not an issue...

You sure that the HP120 is two inches taller than an AL80? I don't remember there being that much difference...

 

[Genesis]

Had a half-dozen of them on my boat yesterday in the racks right next to my AL80s

 

[SeaJay]

Those are "regular" HP120's, right? The new "E" series might have different dimensions...

Here's what I've found:

Pressed Steel LP120: 29.37 inches long
Pressed Steel HP120: 27.87 inches long (This is what you had on the boat yesterday, right?)
Pressed Steel HP120 "E" Series: 28 inches long
Pressed Steel HP119 "E" Series 8" diameter version: 24 inches long
Standard AL80 is typically about 24.5 inches long.

...So you're right, but there is an 8" version of the new E series that's about the same length.

 

[Genesis]

The larger-diameter tank though is a PITA. Those are heavier and more like an LP95 in terms of dimensions.

The HP120s would be fine as a single, but I suspect they'd be a PITA to have as a set of doubles, if only because of the length.

The HP100s are MINISCULE by comparison, and IMHO they're "just right" for most no-deco diving - if your SAC is reasonable (mine is typically in the 0.6-0.7 range when spearfishing) you'll likely run out of NDL on Nitrox before you run out of gas. I usually do that now on an AL80, but this will give me significantly better safety margins.

 

[MikeFerrara]

Genesis once bubbled...
I refused to buy the old PST HP100s because they had a funny neck thread, thus making them usable ONLY with the valves they come with and a handful of others. If you decide you want to double them, the only people who made a manifold that would work at the time was Genesis, and I HATE their DIN manifold (the angled connections just don't do it for me.)

DiveRite makes a manifold that works.

 

[MikeFerrara]

SeaJay once bubbled...


The only thing that I don't like about this setup are the DIN valves. Despite what many others say, I'm not a fan of DINs. They hold water which can't be blown out... And there's the O-ring issues...


...Gonna play first.

Who told you that?

 

[divegary]

aluminum 80s are a tad over 26 inches long, PST E7-120 is about one and three quarter inches longer. PST E7-100 is twenty four inches, two inches shorter than the AL 80 and weighs the same when empty- 31 lbs. PST E8-130 are the same size as AL80, but weigh 44 lbs. empty. Some divers need the longer tank,120, to give them some weight over their butt so they do not tip forward. I love steel- PST E7-120 or HP120 double or singled. Best way is to rent or borrow what you desire to see if it is a smooth fit for you. Dive Safe, Dive Often.

 

[Genesis]

are 8" tanks. Those are not only heavier but larger in CIRCUMFERENCE than the HPs and AL80s.