LP95 or even LP108 for Sidemount Diving?

[victorzamora]

So should I buy another set of LP85 or go a little bigger while I'm there?

IMO? It depends on your use-case. Dedicating tanks makes sense quickly with helium. Just simple math, filling LP108s with 18/45 costs ~$160 ($0.12/ft3 of EAN32 and $1/ft3 of He). Dumping that gas just a couple times will quickly add up to the cost of a set of tanks.

However, you ask what size you should get....and that's where use-case comes in. I know a lot of guys like bigger tanks for Trimix for the additional bottom time with increased gas consumption. However, most of my diving has been in caves....so that may not be as necessary on OW tech dives. Another factor is buoyancy characteristics. A lot of guys I know much prefer the notably-more-negative HP149s as they behave a little better when filled with high-helium mixes.

If your expected/projected dive profiles need LP85s plus a stage, LP108-sized tanks make a lot of sense. If you barely even expect to need LP85s, then there's no benefit to carrying bigger/heavier tanks and Hypoxic mixes will quickly justify another, bigger, set of tanks.

 

[tbone1004]

@rjack321 HP120's won't get him anything over the 85's, and the HP130's are just high pressure versions of LP95's. The downside of going to the HP cylinders is that you have to change your weighting when switching bottles. I find that immensely annoying so if you are staying with LP85's, then I would go with LP big bottles.

HP130's are much more negative than LP121's, about 3lbs each. LP121's are almost as light as AL80's when empty.

 

[rjack321]

I don't know what lp85s he's using. The fabers are significantly lighter than the Worthington's. HP130s are longer than lp95s and trim out better imo, but that'll depend in his body. The heavier 130s are an asset, although you get used to changing lead around up here, its not a big deal.

I would not get 121s or even 108s, the boat is going to hate him. Plus they are pretty rare up north and just unnecessary. 95s (fabers) are plenty of gas for normoxic wreck trimix dives to 220ft (which the OP isn't even certified for yet), readily available, and not going to break the bank for a cylinder that will spend a decent chunk of each year in the garage.

 

[Caissy]

@rjack321 I'm diving Faber LP85s at the moment. I've been to 160' on air many times so far, but narcosis stops me from going any further... Hence my goal to get certified for normoxic gas. But since I'll need another pair of tanks for these 160' to 220' wreck dives, I figured I would go with slighly bigger to account for the extra consumption at the greater depth...

So far, the LP95s and the LP108s seem the best candidates for what I'm planning to do.

 

[tbone1004]

@rjack321 since the Fabers are the only ones being made I went with that

I did make a mistake though, the 95's are the 117/119's and 108's are 130's

 

[northernone]

@northernone how high are you pumping those?

Remember the first rule of cave fills? : D

...not the throw a wrench in the discussion, if you can pick up some used LP tanks slightly bigger than you have now... they hold their value well until you get a better sense if you want more/bigger bottles or are happy with the bottom times they give you already.

 

[tbone1004]

@northernone even ignoring van der waals which is very legit at this pressures, you would be pumping to 250psi over the hydro pressure of those tanks... I think you mathed wrong.

 

[northernone]

Another idea. By spring I may have a pair of lp95s and lp131s (needing a ride back from Florida). I live 1200km north but am into Ottawa/Montreal area somewhat regularly.

You'd be welcome to borrow them for a couple weekends and see for yourself.

 

[bamafan]

I have lp108's and honestly I prefer my lp120's for sidemount. I can't tell the difference in weight but a definite difference in gas volume. I generally dive 3 tanks in Florida. Lp50's, hp100's and my lp120's. My lp108's are hardly used

 

[tbone1004]

I have lp108's and honestly I prefer my lp120's for sidemount. I can't tell the difference in weight but a definite difference in gas volume. I generally dive 3 tanks in Florida. Lp50's, hp100's and my lp120's. My lp108's are hardly used

I agree, however you're tall, I'm tall, I don't consider 5'10" tall enough for 121's, no offense @Caissy