High Pressure vs. low pressure

[cpd123]

I can't decide if I should get a low pressure 95 or a high pressure 100. Which is better? And which manufacturer should I buy from?

[Rainer]

There is no "right" answer.

Can you reliably get HP fills (I mean 3500psi once cooled)?

Can you get LPs overfilled?

Do you plan to transfill into this cylinder?

Do you plan to do your own PP mixing?

Are you comfortable with the extra weight of the LP? The extra width?

Worthington and PST are what I rock. HDG finish is what I look for.

[BouzoukiJoe]

Definitely no "right" answer.

To make matters even more complicated, at least Faber has 2 different types of tanks that people might call HP tanks. The 3500psi versions are much heavier than the 3442psi versions, so you need to consider weighting issues (how much, distchable vs non-ditchable, etc) when choosing your tanks. A cold-water diver will probably prefer the heavier tank.

FWIW, I have FX120s (3442psi) and I often get short fills. When I learned to plan for them being 105s I became much happier. As a matter of principle, I'd rather underfill an HP tank than overfill an LP tank, though
there's something to be said for LP tanks if you can get over-fills.

[Rainer]

Oh, and then there's cost. My LP85s are (shhh) 100s (or sometimes 120s...) with the fills I get. I paid about $150 less compared to the equivalent capacity HP (per cylinder). That said, I also do have some (true) HP100s and HP130s.

[Jack Hammer]

I prefer HP tanks, but you'd have to compare different capacity tanks to see why. A LP95 overfilled to 3442 psi gets you ~123cf gas and has about the same physical dimensions as a HP120 tank. A HP120 filled to 2700psi gets you ~95cf gas. You can safely underfill a HP tank (that is about the same physical size, yet lighter) to get the same amount of gas a fully filled LP tank of similar dimensions gets you.

So if you plan on overfilling a LP for higher capacity, you should be comparing a LP80 to a HP100 and a LP95 to a HP120.

Jack

[Rainer]

Originally Posted by Jack Hammer

I prefer HP tanks, but you'd have to compare different capacity tanks to see why. A LP95 overfilled to 3442 psi gets you ~123cf gas and has about the same physical dimensions as a HP120 tank. A HP120 filled to 2700psi gets you ~95cf gas. You can safely underfill a HP tank (that is about the same physical size, yet lighter) to get the same amount of gas a fully filled LP tank of similar dimensions gets you.

So if you plan on overfilling a LP for higher capacity, you should be comparing a LP80 to a HP100 and a LP95 to a HP120.

Jack

Um, sort of depends on what pressure you intend to overfill to, doesn't it? I usually push my LPs to 3000, but sometimes to 3600. The question should simply be to what pressure can you overfill (and what pressure do you want). For me, it's all about capacity, not pressure.

[skdvr]

Originally Posted by Jack Hammer

I prefer HP tanks, but you'd have to compare different capacity tanks to see why. A LP95 overfilled to 3442 psi gets you ~123cf gas and has about the same physical dimensions as a HP120 tank. A HP120 filled to 2700psi gets you ~95cf gas. You can safely underfill a HP tank (that is about the same physical size, yet lighter) to get the same amount of gas a fully filled LP tank of similar dimensions gets you.

Jack

I agree with this. I have no problem getting HP fills at my LDS, so I have HP tanks. I would not want to keep pushing my luck or the luck of the Tank Filler for overfilling a LP tank. All though they have a pretty good track record in Fl where Overfilling LP tanks is fairly common. I still would rather fill a tank to its rated pressure. If I do not need a ton of gas I just tell the person filling my tanks to take them to about 3000 or 3100 and stop. When they cool down they are in the 2700 range which is still plenty of gas (HP 130 & 120's). If I want a full fill I usually leave them there for a few hours so that they can cool off. If I do not have a few hours and I want a pretty close to full fill they just fill them super slow. I personally would not buy a LP tank for my needs around here unless I got a great deal on one. I will stick with HP, but LP work better for some people...

With all that said I think that a HP 100 is a sweet tank.

Oh and I prefer Worthington tanks because of the Hot Dip Galvanized finish, which has also been mentioned by Rainer too. Great finish on the tanks. If I got a killer deal on some Faber (painted) tanks I would not pass them up espically because I dive fresh water, but I really like the worthington finish and buoyancy characteristics of worthington too. Some of the Fabers get positive when they are empty, which for the mainly cold water diving that I do would not be great for me...

Phil

[Rainer]

Originally Posted by skdvr

I would not want to keep pushing my luck or the luck of the Tank Filler for overfilling a LP tank. All though they have a pretty good track record in Fl where Overfilling LP tanks is fairly common.

Pretty good track record? Or do you mean perfect?

[rab]

The fill station (as others have said) makes all the difference. My tanks are 119ft[sup]2[/sup] at 3442psi, but I only get a true fill in Florida (where it often is 3600). In Ohio, I think the best I have ever received is about 3200-3300 -- operators just don't know what pressure to fill to in order to get 3442-ish when cooled. (or can't get to that pressure when the tank is warm/hot from the fill)

-Rob

[Splitlip]

Originally Posted by Rainer

Pretty good track record? Or do you mean perfect?

I'm finding it a little more difficult to get LP tanks pumped up on the coast. Cave country may be a different story. I was always happy with 3000 in an LP. Recently bought some HP 100s. (Actually 3442). I am happy with them. Even filled to 3000 I am still ahead of the game.