LP, HP or aluminum

[Wyno]

.

 

[ScubaDan]

I guess I will go with the steel but I still do not know if I want HP or LP. I can get a HP 120 that is a little less than 2 inches longer than aluminum 80 and about the same weight (36lbs). If I go with the LP 104 which is the same length as the aluminum but 9lbs heaver (45lbs) than the HP 120.

I’m guessing most of you would get the LP 104.

 

[detroit diver]

If you ever dive doubles, you'll be happier with the LP 104's. So if you're going to buy a steel tank, I'd recommend buying one of those.

 

[ScubaDan]

I will be diving doubles at some point. But since I am new why would I be happier with the 104’s.

 

[detroit diver]

Because you won't have to purchase 2 tanks when you go to doubles- you'll only have to get 1 additional 104.

 

[ScubaDan]

So you saying that the HP 120's would not make good doubles

 

[Padipro]

I'm not a teck diver, yet, but I do play one on TV. Seriously though, I've been reading everything I can get my hands on about teck diving, mainly deep, mixed gas diving, and there is one thing everyone has failed to mention about the differance between LP and HP tanks. Compressability, or how well a gas tolerates being compressed. If you intend on getting into mixed gas diving, ie Trimix, the compressibility of Helium, goes way down the higher the pressure. In other words "The higher the pressure it is compressed to, the less additional volume one gets for the effort." This isn't much of a problem below 3000 psi or when using gas mixtures of air and oxygen but above that pressure and when using gasses like Helium or Hydrogen it becomes a real problem, you can continue to compress the gas and it really won't be adding much more gas to the mix.

When I first started looking into the Teck side of diving I was confused about why everyone seemed to be carrying around these massive LP steel tanks when you could get a HP steel tank that was so much smaller with nearly the same volume. Then I started researching it and found out about this compressibility factor and realised that it was much more efficient to use a LP tank with a high volume then it was to try to compress the gas to a much higher pressure in a smaller volume tank.

Again, like some of the people here have said, the type of tank you use depends on the type of diving your doing. I use HP steel 100's for my recreational diving when I'm using Nitrox and AL 90's for my doubles when doing deeper wreck penetration. I'm not Trimix qualified yet, and in the warm ocean waters down here alot of people I've spoken with suggest AL tanks for doubles because with all that gear on one is so negitive to begin with you don't need the added negitivity of the steel tanks, although some people do use them.

Scott

 

[detroit diver]

That's correct. The weighting is just way off for them. You'll be happier with the 104's.

Don't re-invent the wheel-most of the serious cavers use 104's and they need to be balanced perfectly.

 

[ScubaDan]

Thanks

 

[WYDT]

detroit diver once bubbled...
That's correct. The weighting is just way off for them. You'll be happier with the 104's.

Don't re-invent the wheel-most of the serious cavers use 104's and they need to be balanced perfectly.

Ditto that! PST 104's are the way to go!!