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Black-Gorrilla
08-24-2007, 19:11
im looking at possibly picking up a set of steel tanks... whats better to have? LP or HP? on an LP it's full fill at (less than 3000 right) and HP is full fill at like 3400?

ScaredSilly
08-24-2007, 22:08
I like LP85s (2400+) the wife has MP 72 (3000+) both doubled.

LP easy fills, epsecially with PP nitrox fills.

HP smaller package, can be harder to get full fills.

cummings66
08-24-2007, 22:34
I like HP tanks. They weigh a lot less than a LP tank of the same volume and like scaredsilly said, the fills are harder to get full.

The pressure is either 3442 or 3500 psi commonly, there are some rated to 4350 but not in common usage.

Flatliner
08-24-2007, 23:37
I haven't bought any yet but my research would indicate that HP is the way to go. Look at it this way, pick the tank that is the size (as in height/diameter) you want and then figure the volume at different pressures. Just because it is an HP120 doesn't mean you couldn't occasionally use it as an LP90.

Black-Gorrilla
08-24-2007, 23:48
well, im 6'4 so any size tank can be strapped onto me... and i can handle some weight too... so i guess some HP steel 100's, even when filled to like 3000 should be enough for a simple fun dive...

in_cavediver
08-25-2007, 08:45
When I want to choose a tank, here is what I do:

1) Decide on the min capacity I want/need
2) Determine the optimal buoyancy characteristics (positive or negative when empty and how much of each)
3) Trim issues - Which tank is easier to carry horizontally when diving

For instance, I'm 5'10' and I want a tank with more than 100cft. I Plan to dive dry so I want a negative tank when empty. That leaves a couple choices. Here's a few. LP120, LP112, HP120, HP119, and HP130. (Al gives + when empty)

Of those, the LP120 is roughly a small water heater which may not be very comfortable to lug around. The HP 120 is extremely long but only 7.25" inches (or 7" can't remember), again to long to be comfortable. The LP112 is just a bit taller than the HP119 (think LP95) and the HP130. They are still quite close in height. One of those tanks would be my choice depending on the specifics of the buoyancy characteristics and what I wanted.

Now, for HP or LP. It doesn't make much of difference. The HP130 is roughly an LP104, the HP149 is an LP120. If you can't get 'full' fills then remember what the 'lp' equivalent is and plan around that number.

I have LP104's and when I get another set, it will either be the HP130's, HP119's or LP112's but most likely the 130's.

cummings66
08-25-2007, 10:00
I like my HP120's, but to be honest the HP100 is a sweet tank. It's almost the perfect tank for diving IMO.

Black-Gorrilla
08-25-2007, 10:41
is there a tank pres. calculator online somewhere? (to figuere out hp 100's at 3000, lp tanks at overfills etc.?)

in_cavediver
08-25-2007, 13:14
is there a tank pres. calculator online somewhere? (to figuere out hp 100's at 3000, lp tanks at overfills etc.?)

The math is easy: here the formula:

Cft rated
---------- * Actual Fill pressure = Actual Cft
Full pressure

OR for an HP 100 at 2600psi:

100/3482 * 2600 = 74.6 cft

Jamesmb
08-26-2007, 21:47
{100/3482 * 2600 = 74.6 cft}

Should that be 3442 instead of 3482?

jeepbrew
08-27-2007, 01:03
I dive HP 130s (purchased from ScubaToys), and wouldn't trade em for any other tank. I love every thing about them.

in_cavediver
08-27-2007, 17:37
{100/3482 * 2600 = 74.6 cft}

Should that be 3442 instead of 3482?

Call it inaccuracy of the gauge or a senior moment.....

ScaredSilly
08-27-2007, 20:36
I should add that for diving singles I think a HP100 is a nice bottle. Even at 3000 you are at 86cuft so it is better than a std Al80 which gives only 78cuft.

But it does not bother me to put 3000 psi in my lp 85s which gives me 96cuft. But we can save the "cave fills" for another discussion.

willardj
08-27-2007, 21:00
LP's is the way to go. I use LP 95's dubed up. I love them. More than enough gas for any type of diving I'm doing. And if you get a good fill
(O-yeah). Thats the ticket and w/ a SAC of .4 to .55 they work great.

reefugee
08-30-2007, 13:09
I have been debating on buying tanks for a while as well. I think I am going to go with a HP100. The tank is about the same dimension and weight as an AL80. However, it has better buoyancy characteristics. And if I can only get the tank filled to about 2700PSI (which should not be a problem), I would still have about as much air as the AL80. I think I am going to go ahead and order the HP100.

DUnder
08-31-2007, 14:02
I don't own any tanks right now but when I buy I will get HP 100. I like having that much air on a full fill, even a short 3000psi fill will give you more air than a AL80 tank. Plus I can carry less weight on my weight belt.

ReefHound
08-31-2007, 14:06
Reefugee, are your current regulators DIN or yoke?

quasimoto
09-18-2007, 13:42
I love my LP's. The only reason that I bought them was the fill issue. I know several guys that have HP's and they hardly ever get a full fill. This will differ from location.

CompuDude
09-18-2007, 20:29
I'm all about the HPs. I'd rather underfill an HP tank than overfill an LP tank, even if the latter has a pretty safe record. And with the HP tank, you're carrying a smaller, lighter package.

Ex: HP100: A full fill gives you 100cf even, sweet! A less than perfect fill (let's say 3300, pretty easy to get around here) gives you 96 cf of gas.

Compare that to an LP95: A full fill gives you 95... as long as you still have the plus rating, else if the shop is anal about it (around here they often can be), you can only get 86cf with your 2400 psi fill. And you're still stuck carrying around a huge, heavy tank! LP95s weigh ~44lbs (full, on land) compared to ~40 for an HP100 (full, on land). Not a huge amount, but look at the difference in the amount of gas you just got handed in return for that extra weight?

It's very easy for an HP100 to have the same amount of gas as an LP95, or more, but it's always going to weigh more (and the tank will always be bigger and bulkier) with the LP95 than the HP100.

BobArnold8265
09-18-2007, 22:18
I bought some steel HP tanks a few years back and love them. Smaller than their aluminum counterparts and when you consider that you need fewer weights when you use them, you actually dive lighter. I'd higly recommend HP steel tanks.

subsur
09-18-2007, 23:28
you should check your LDS - some places don't fill HP, so there would be no point of buying HP if you can only fill it to 3000. Also, might depends on your size and your diving. diving in cold salty water - HP is the way to go.

CompuDude
09-19-2007, 00:42
you should check your LDS - some places don't fill HP, so there would be no point of buying HP if you can only fill it to 3000. Also, might depends on your size and your diving. diving in cold salty water - HP is the way to go.

Good point. I would HOPE those places are few and far between, but should you have the misfortune to live in an area where NO ONE does HP fills, that would definitely be a justification for LP tanks.