LP or HP

[Divenomad]

Sorry if this is asked and answered. Debating between LP or HP double setup. If you go HP, you might have some trouble getting good fills, if you go LP you get good fills, less gas ( I tend to go through gas slightly faster than most) More gas I think is better.

One dive? LP tanks? Boosters? Two sets of HP doubles? I'd appreciate your thoughts.

-Nomad

 

[rjack321]

Depending on where you live, you might find LDS's filling "lp" tanks to greater pressures than even "hp" tanks are rated to (nowadays 3442psi).

So the most salient question is what does/will your local shop fill to? Are they filling a hp100 in 2 mins and its cooling down to 2900psi? Are they filling "lp" tanks to 3800psi cold?

What tanks do you own now? And when you pick them up what is the delivered pressure?

 

[Divenomad]

My current fills are very good, almost 3442 after cooling in the ocean. I have no complaints whatever about that. My concern is on boats or when traveling to other areas of my state. Some shops only fill to 3000, some boats as well, despite having the capability of filling higher. That is why I posed the question about #of dives, boosters, multiple setups and whatnot. If I'm going to invest in this, I might as well get it right.

Nomad

 

[Meng_Tze]

My current fills are very good, almost 3442 after cooling in the ocean. I have no complaints whatever about that. My concern is on boats or when traveling to other areas of my state. Some shops only fill to 3000, some boats as well, despite having the capability of filling higher. That is why I posed the question about #of dives, boosters, multiple setups and whatnot. If I'm going to invest in this, I might as well get it right.

Nomad

The answer is in your response above......

If your boat and other shops only fill to 3000... do you have more gas in a LP108 or a HP100? (or take two other sizes)

 

[Divenomad]

The answer is in your response above......

If your boat and other shops only fill to 3000... do you have more gas in a LP108 or a HP100? (or take two other sizes)

Well, I'm a short little bugger, built like a fireplug. Weight is not an issue. I don't want larger tanks to be too awkward or to screw up my trim. So, HP 100 or LP85? SAC rate and run time become factors, based on gas supply. I get my bottle filled locally, I get a good, accurate fill per my requested mix. What do people do when out of their normal area of operation, and how much of a problem is it? Is it even worth thinking about?

Nomad

 

[Gombessa]

If those are your choices, then it's pretty easy. HP100s and LP80/LP85s are very similar in terms of weight, dimensions and trim, and they essentially hold the same volume of air if filled to the same pressure.

Since you seem to have no problems getting your tank filled to a good working pressure, I'd say go with the HP100s. At least that way, you'll have a leg to stand on if a shop/boat gives you a fill to 3000 and you want them to top it off. And if they won't, at least you know you have no less gas than if you brought in an LP80 instead.

 

[Divenomad]

Yeah, see that makes sense to me. I was leaning toward HP 100's. Not too big, not too small, jusssst right.

 

[gxsr_sarge]

I was doing the same research and asking the same questions when shopping for my second set of doubles for my upcoming cave course in High Springs. Everyone's opinion (especially when it related to cave diving) was to go with the LP's b/c you CAN overfill them and get a lot more air. Fills are not an issue with me b/c I have my own P/P blending station at home (and that I could take on the road). In addition, the LP's seem to trim out nicely (at least for me) whether they are 85's, 95's, 104's or 108's.

I finally decided to go with twin XS Scuba (Worthington) LP108's. They are a bear on land or in a boat but sweet in the water. I went with the LP108's because in caves, more air is a good thing. Since cavers deal with the rule of 1/3's, bigger tank = longer time/turn pressure.

Given your current two choices (LP85's v. HP100's), consider this: If you do get that 3000psi fill (at the LDS or an a boat), with the 85's, you still get more air (about 96 Cubic Ft) v. with the HP100's (87 Cubic Ft.). At 3500 PSI - it's 112 Cubic Feet (LP85) v. 101 with the HP100 (techically rated at 3442, not 3500). I have three HP tanks and I found that it was becoming increasingly more challenging to get true 3500 fills anywhere. This is one of the many reasons I decided so spring for my own fill station.

Good luck!