Tank recommendations

[-JD-]

I am a long-torsoed 5'10" and dove the long PST 3500HP 120s without issue, but I also mount my tanks pretty high for balance.

HP80s would not be my first choice. More gas is better. Downsizing just to match a buddy makes no sense.

 

[rhwestfall]

To the OP, yes a steel tank has many benefits, but will also likely cost a fair amount more. I see you are 18 years old, and I doubt you are financially in a position of many here giving advice. No harm in picking up a pair of used AL80's and getting to do some diving with the money you save. Years later, if you make changes, sell them to someone in the same position.

 

[rx7diver]

Why recommend such a short tank to a 6' diver? What advantage does it have for him over the HP100 or one of the larger tanks?

@rongoodman,

I am 6'2". The HP80 has worked extremely well for me--when I wear a full thick wetsuit. It works, too, for a thin wetsuit, but it is really too (relatively) negatively buoyant (-4 lbs empty in fresh water, IIRC) for this for me.

Being only 20" tall, it doesn't take up much space in the car.

Being relatively lightweight full, it is relatively easy to schlep and self-don out of the water even if a table, etc., isn't available.

Important here is the fact that its capacity will more closely match an Al 80's, the cylinder that the OP's buddy will be diving.

My HP80's are my first cylinders. I've owned them a very long time. When I began diving deeper/longer drysuit exposures, I purchased HP100's (lovely cylinders for this), which I eventually replaced with HP120's for even longer/deeper drysuit exposures. I still own the HP80's and HP120's.

My HP80's still work marvelously (for me) for three-season, wetsuit recreational diving in MO and AR fresh water.

rx7diver

 

[rongoodman]

I don't see how they fail to make a taller diver head heavy. People sometimes have trouble staying flat in the water with doubles for the same reason, ending head-up in order to compensate. I also don't see why having less gas is ever a good thing.

 

[rx7diver]

I don't see how they fail to make a taller diver head heavy. People sometimes have trouble staying flat in the water with doubles for the same reason, ending head-up in order to compensate. I also don't see why having less gas is ever a good thing.

Manifolded doubles are a different story. There's a lot of brass up top (manifold and two first stages, probably). In my case, in order to easily manipulate my manifold valves, I needed to wear my manifolded cylinders higher--which, indeed, made me head heavy in manifolded HP80's (20" cylinders).

For me, things improved when I wore manifolded HP100's (24" cylinders)--though I was still a bit head heavy when I wore them at a height that allowed me to easily manipulate my manifold valves.

For me, manifolded HP120's (28" cylinders) are the perfect length for wearing at a height that allows me to easily manipulate my manifold valves. But I wore these for extended range, drysuit diving on Great Lakes shipwrecks. I do NOT wear these for the types of MO and AR fresh water, wetsuit, recreational dives I do now.

The OP describes dives in Idaho that seem comparable to the types of single-cylinder, recreational, buddy dives I do here in MO and AR (when I'm not diving solo, that is). My HP80 works marvelously for me for this type of diving--for the reasons I listed above.

rx7diver

 

[sourdough]

+1 for HP steel. I even prefer HP100s in warm waters.

 

[Capt. Bas]

It is worth asking. My understanding is that many fire companies have moved to 4500psi SCBA systems so getting a 3500ish fill may not be a problem.

That will be a problem as in Europe a 300B 4500psi Din Fill whip is not fitting in a 200b 300psi valve, and a 300b fill whip should not fit a Din/Yoke adapter.
exchanging a 3000psi Yoke valve to 4500PSI Din on a 3000psi Cylinder is not the best idea and not allowed recommended as you are able to fill above your test pressure for the cylinder.
Another option will be a Steel 12l/300b cylinder. you only need a 300bar din first stage in this case.
no idea if these cylinders are available in the US and how the will be called in imperial measurments.

Enjoy diving!

 

[broncobowsher]

That will be a problem as in Europe a 300B 4500psi Din Fill whip is not fitting in a 200b 300psi valve, and a 300b fill whip should not fit a Din/Yoke adapter.
exchanging a 3000psi Yoke valve to 4500PSI Din on a 3000psi Cylinder is not the best idea and not allowed recommended as you are able to fill above your test pressure for the cylinder.
Another option will be a Steel 12l/300b cylinder. you only need a 300bar din first stage in this case.
no idea if these cylinders are available in the US and how the will be called in imperial measurments.

Enjoy diving!

To further confuse thing (adding international boarders and how things are done in different countries is also part of that confusion) is that a standard fire department SCBA fitting is different than SCUBA fittings. But that can be an advantage as you will need an adapter to make the two work together. It is just a matter of the right adapter. Or more commonly two adapters with a common junction (usually NPT here in the states).

The quick attachment (yoke, 232b DIN, 300b DIN, SCBA, etc.) are made that way to prevent attaching the wrong tank to the wrong fill (or discharge) device when used in a repetitive manor. But the parts that have the specialty quick attachment points on one side, typically have a common attachment point on the other. So making fill adapters is really easy.

 

[myself]

So, I have seen lots of talk about steel tanks, but very little on aluminum, is there a reason that steel tanks are so favored over aluminum for this type of diving? I also have to wonder what the difference in longevity is between steel and aluminum.

 

[runsongas]

lp72/lp85 also ok if you happen upon a deal or end up getting your own compressor for overfills.

@myself aluminum is worse weight to capacity hence why steel is preferred. aluminum is popular for rental fleets because they are cheaper to buy in bulk and they tolerate corrosion/abuse better in tropical environments. the buoyancy difference does make aluminum 40/80 useful for deco/stage usage.