How do I choose my tank? HP vs. LP 80-130 cuft??

[RaginCajun]

Hey folks,

Yeah I'm a newbie, so what better than to learn from my more experienced peers....so here goes my current dilema:

How do I choose my tank?

So far I see the differences as:

Steel vs. Aluminum---(different buoyancy characteristics)
HP vs. LP---3000 psi vs 3442


So I'm a new diver ok, but I'm buying gear and want to purchase something now that I'll use for many years. Oh and I have a Nitrox class in a few days, so I plan to dive Nitrox too. Right now I like the HP and higher capacity tanks, from purely a volume/time of air perspective (read safety). But should I save a few bucks and go for a pony bottle for safety? So many questions...

I should also mention that yes I'm a newbie, I'll probably dive the La/Tx coast and perhaps other GOM destinations then perhaps some really nice trips to the carribbean etc...so warm water diving, seawater mostly, but some lakes, lagoons etc, no cave diving!! (not going through the training..)

Granted there are certainly cost differences between the two, buoyancy characteristics cost and weight benefits/consequences.

SO I just wanted it to throw it out there:

What do you dive with and what would you recommend for a new diver?

Sincere thanks!!

 

[Mark Vlahos]

One often overlooked factor by new divers when choosing a cylinder is your physical size. For example if you are tall you will probably be happier with a longer cylinder. If you are short then a short cylinder will probably be more to your liking. I like steel more than aluminum, but as a new diver I would encourage you to just rent a cylinder for a while. If possible rent different types.

I am 6' tall and 220 lbs, for me a 130 cubic foot cylinder is a pretty good size, it is about as tall as the ubiquitous AL 80 but has a larger diameter, being steel it is heavier and this allows me to remove lead from my weight belt.

Mark Vlahos

 

[The Kraken]

I'm a little shy of 5'8" and dive a HP steel 119.
I weigh in at about 175.
The E8-119 fits me perfectly, trims out beautifully diving wet or dry and has plenty of reserve gas if diving with those divers who are diving Al 80's.

I like the aspect of extra gas for the safety factor.

the K

 

[cummings66]

I'm not sure height has a lot to do with it. I'm 6' 180 lbs and own steel HP120's and steel HP100's. I've dove steel HP80's and believe it or not the HP 80 gives me perfect trim. The HP100 is pretty good and the HP120 is a tad foot heavy for me. That's all in a drysuit. The wetsuit seems to be a little different but still similar. So you have to do a bit of arranging to get the trim right.

I can reach the valves on the tanks when I dive as well, they don't hang low on me in other words.

Height comes into play I'd say for short people who just physically would be dwarfed by the taller tanks. I've seen some that the HP80 is a perfect fit for where on taller people like me it looks like I'm missing something.

 

[piikki]

I bought tanks soon after I certified, and made mistakes. I knew I wanted steel for several reasons, and that part I did not regret. I thought HPs made a lot of sense and that is what my LDS pushed too (indeed totally put LPs down -"what an idiot would buy LPs when HPs are around). After being around scuba just a year, I can see why people have LPs. Now I have both HPs and LPs, and I might very well get rid of the last HPs I have even though that is not such a huge problem personally. (The usual reasons of not getting full fills everywhere and basically just not wanting to deal with different size tanks).

The biggest mistake was the one people have already mentioned. I got absolutely no guidance regarding body size versus tank size. I bought too small (stumpy) tanks for myself. There was absolutely no way I could get them to trim nicely. I could do OK but I could not do great with them. I am 5'10 and I had heavy Faber HP80s. I was nose-heavy, and at one point I just decided I do not wish to be, and swapped them to LP85 which are great. My HPs are HP100s and they trim out great with my frame too.

I really would have liked some of this to have been covered in the OW course at least in a mention. It would have been nice if LDS would have offered some insight into this too. Make sure you at least try to ask the place you are buying if they'd offer some assistance in choosing a tank. Better yet though if you can get independent assistance and get to try out different tanks. It can be a huge difference to dive a tank that 'fits' versus a tank you can not position in any logical way to keep you in a trim you do not need to fight to keep.

 

[Tek Adventure Diver]

Hey folks,

Yeah I'm a newbie, so what better than to learn from my more experienced peers....so here goes my current dilema:

How do I choose my tank?

So far I see the differences as:

Steel vs. Aluminum---(different buoyancy characteristics)
HP vs. LP---3000 psi vs 3442


So I'm a new diver ok, but I'm buying gear and want to purchase something now that I'll use for many years. Oh and I have a Nitrox class in a few days, so I plan to dive Nitrox too. Right now I like the HP and higher capacity tanks, from purely a volume/time of air perspective (read safety). But should I save a few bucks and go for a pony bottle for safety? So many questions...

I should also mention that yes I'm a newbie, I'll probably dive the La/Tx coast and perhaps other GOM destinations then perhaps some really nice trips to the carribbean etc...so warm water diving, seawater mostly, but some lakes, lagoons etc, no cave diving!! (not going through the training..)

Granted there are certainly cost differences between the two, buoyancy characteristics cost and weight benefits/consequences.

SO I just wanted it to throw it out there:

What do you dive with and what would you recommend for a new diver?

Sincere thanks!!

I recmmend a LP steel. You want to use lp because nitrox is better with lp as well that you will never get a true fill with a hp tank. Now a 95 is a good place to start. It will take of some weight from your weight belt.

 

[SparticleBrane]

I recmmend a LP steel. You want to use lp because nitrox is better with lp as well that you will never get a true fill with a hp tank. Now a 95 is a good place to start. It will take of some weight from your weight belt.

"Nitrox is better with LP"
...and your source for this is...? Funny how in cave country they push tanks past 3600psi with nitrox in them, and there aren't any problems.

"You will never get a true fill with a hp tank"
...again, where's your source for this? I've filled plenty of 3442 tanks and never left anyone short.


So, let's use your example of an LP95. I'll suggest an E8-119 if you can get your hands on one. Thatcher, what are the advantages and disadvantages of each?

 

[Mark Vlahos]

Low Pressure is better for Nitrox when the method used to fill the cylinders is Partial Preaaure Blending. Since the end pressure is lower the pressure needed of the initial fill with pure oxygen is lower. In short it is easier for the blender.

Having said this I might suggest that when choosing a cylinder select the cylinder size and therefore volume based on the LOW PRESSURE range of size options. Once you have made this choice look at the high pressure versions of that cylinder and purchase that one. I will use the Pressed Steel comparisons...

A low pressure 95 is comperable to a high pressure 119
A low pressure 104 is comperable to a high pressure 130

If you purchase the high pressure cylinder of the same size as your low pressure choice you always have the option of selecting the fill pressure you want. If you have chosen the second cylinder in my example above at low pressure you will still have 104 cubic feet of gas, if this is plenty then you are good to go. If you need more gas you can choose to safely pump that cylinder up to the higher pressure and you will have 130 cubic feet of gas. A high pressure cylinder gives you more options for volume than a low pressure cylinder. Of course low pressure cylinders are usually less expensive, but that choice is up to you. In most but not all casees the weight characteristics of the low and high pressure cylinders of the same size will be pretty close.

Have fun,

Mark Vlahos

 

[Vicente]

1. Are you really diving the same tanks in Gulf waters and the Carribean? Unless you are a long-haul truck driver or something that seems like an awful lot of lugging around of tanks. When I go to the Carribean I rent tanks and typically it's the Al-80, although sometimes I ask if they have a Steel-72 in the pile and often as not they have one. I like steel and am not an air hog.

2. Water temps, diving environs, and body type of diver matter a lot.

Example my chica is MUCH better off with the XS-Scuba HP-80 tank recently aquired. She is shorter and it's compact so she is not banging her head against a valve so often. The tank is 9 lbs negative full so that means less weight on the belt. It's cold water here so that can mean 20-30 pounds lead to balance thick wetsuits and an Al-80, and often shore diving here so you have to hump that load down the stairs across the beach into the surf. The HP-80 is lighter than an Al-80. Knocking 10 pounds or more off your weight is a good thing, the chica gets less tired which is good for both of us.

There's a web page somewhere that describes the Al-80 as a cruel joke inflicted on novice cold-water divers.

I use an identical HP-80 too just to keep matched with her and it's a great little tank. Although, I come back with 40 cubes or more she's the n00b ASD. I'll probably pick up another steel about 100 cubes before long to use when diving with experienced divers where I can actually get good use of a tank.

Steel is better IMO. If you dive much you will end up with some HP and some LP. The LP85 also looked nice to me, a friendly LDS might overfill one for ya and get it up to 95-100 if asked nicely. Just flip a coin and go for it.

I bought an Al-80 early on and used it heavily for the first couple hundred dives. I got it cheap and and to me there's not THAT big of a difference in tank choice to justify obsessing over it. Buy something, and go dive it.

 

[spectrum]

1. to me there's not THAT big of a difference in tank choice to justify obsessing over it. Buy something, and go dive it.

As much as I despise the AL-80 for cold water diving there is a lot of truth in what you say.

We all adapt to handling our gear and while some choices will be a bit more demanding how different is 65 pounds of gear from say 77? For weaker/smaller divers this can be important but for 95% of divers it's a wash.

You can dive what you want for a cylinder, however unless you are the first to hit turn pressure all of that planning will just make the next fill easier for the dive shop. Havng a surpless of air on hand is not a bad thing either. However, carrying an excessively sized cylinder will to some extent be a self fulfilling prophesy of consumption

On HP cylinders I find that I get just as good a fill as my AL-80 and LP buddies. In any case it's important to make the dive shop know that you are willing to wait for a good fill and that you expect them to provide same.

We started out with 4 HP-80s. I latter picked up a pair of HP-100s thinking they's be handy for seeper longer mor ambitious dives. My wife being the bigger air user has latched onto the 100s and while not an especially strong person adapted almost instantly to the added 10 pounds overall.

Within reason you can't have too many cylinders so just start buying!

Pete