High pressure vs low pressure tanks

[Tortuga68]

I tend to look at it the opposite way. An LP tank tends to be big, heavy and 2/3's full. Compared by approved capacity, LP120 vs an HP119 for example, the LP120 is 10 lbs heavier and 5 inches longer. Even when you compare tanks with similar dimensions, LP80 vs HP100 for example, the weights are nearly identical

Is that full (of gas) weight or empty?

 

[Rusty Nail]

Good point chrpai, I should've been more clear. I understand that you can have 4000 psi in a small tank as well as a large tank, I just want more air. As others have stated in this thread, my skills are where my attention may need to be in order to achieve more bottom time. I consider myself on track for the amount of dives that I have. I read the article that Scuba Steve recommended ( NWGratefulDiver.com) found it to be extremely helpful. Thanks everyone for your input, that's why I'm here.

 

[ScubaSteve]

...... I read the article that [-]Scuba Steve[/-] Jim Lapenta recommended ( NWGratefulDiver.com) found it to be extremely helpful. Thanks everyone for your input, that's why I'm here.

Credit where credit is due

I think you have a lot of good information in this thread......this thing we do, scuba diving, is an adventurous journey, not a destination. Have fun getting to where you want to be. I have yet to get there because as I continue my journey, my destination changes for the better.

 

[uncfnp]

And don't think that just because you need more gas that it makes you less able as a diver. Your gas consumption will go down with experience but sometimes even the best divers just use more air for many reasons, including size and gender. My dive buddy has a very good SAC but will always need a larger tank than I. Many very experienced divers use larger (cf) tanks to maximize bottom time.

 

[Hatul]

I'm considering buying my own tanks and would like to know what tank would let me get the safest, fullest fill. Being new to the sport I still have some minor issues with running out of air faster than others. On average, about 25 minutes @ 80 feet is max for me. According to my Vyper Air computer graph, I burn most of my air during my decent and the first 5 minutes I'm on the bottom (over 200 lbs every 2 minutes.) and then I settle down.
So my question is: Is there a tank that I can fill to around 4000 psi to get more bottom time?

You diagnosed your own problem and the solution is to learn to control your breathing a relax from the start. Part of this will come from sheer experience as the initial excitement decreases and part has to be practiced.

 

[eelnoraa]

I prefer HP tanks now because I can get good fill here.

I have had two minor issues with LP tanks:

1) you have to get + rating to get official 2640 fill. When hydro, you have to specifially ask for it. If you forget, or the LDS forget, you will lose the + rating. Once lost, you can't get it back. So LP95 becomes "LP86". LP85 becomes "LP76".

2)If you have good relationship with your LDS, they may be willing to give you a fill to 3000 or more, but this is not garranteed. Some LDS will go by the rull and give you 2400 fill only.

But more than a few time, with of 7.25" LP85 type of tank, often LDS think it is HP100 and give me 3400. I got myself "HP109"

 

[kelemvor]

I put this chart together when I was deciding what tank to buy. I went with LP108. I've never asked for an overfill, and only once have I had a fill less than 3k, even when traveling.

The 8" dia tanks do tend to be a pita on dive boats, but it's manageable.

http://www.kellyphotos.org/tanks.htm


Red cells are >al80 (worthington) value, green are <al80 value Units are imperial.

 

[Superlyte27]

I'm so glad I live in the area I live in.
The nazi stories you guys tell me are frightening.

 

[chrpai]

I'm so glad I live in the area I live in.
The nazi stories you guys tell me are frightening.

I know one shop that will give me AL80's with 3300 every single time. Hand them an LP95(+) and it comes back as 2400. Come back and ask for a top off to 2640 and it's like pulling teeth. Don't even think about getting a full HP fill. It's getting better but it's tough...

 

[dytis-sm]

I am a fairly new diver (certified in Sept 2011) so this experience is fairly recent in my head. I had since accumulated 80+ dives and as everyone mentioned the key is figuring out your buoyancy. The extra air is nice but eventually you will end up carrying more air than you will need when diving with others. Like you I rushed and bought a HP 130 so that I can keep up with my team. But as I worked on my buoyancy the need for the big tank dissappeared and now I am at half tank when my buddy is ready to end the dive. I also have to watch out for going into deco as I have consistently more air than my NDL. My advice is to stay around the 100 cf tank which is practical capacity. Also stick with steel. It is heavier but will help you drop extra weight from your belt and manage your buoyancy.

As every one else mentioned buoyancy is the key in your consumption and it has been a challenging diving aspect but eventually if you dive often and work on your breathing/weights/trim your consumption will get better. Until then just shallow your pride and end the dive sooner than the rest of your group. Nothing wrong with that. On the buoyancy training, checkout the extreme scuba makeover videos by UTD. These helped a lot and I rented them from Amazon at a minimal fraction of what the UTD course costs. Great reference on where to start...