A few newbie tank questions

[MrVegas]

After getting certified this summer and buying most of my other gear, I am considering finally getting tanks for my son and I. Just singles -- we have actually been in the local quarries quite a bit, and these would likely never see salt water. Frankly, the tank choice is a bit overwhelming -- we've sort of used whatever the rental places gave us. (Last time it was low pressure steel 72s filled to about 2000 PSI, but we've had standard aluminum and other steel tanks as well at various time.) However, not everyplace rents tanks, and the desire to just stick them in the car and go is getting to me.

I'm pretty open to about anything if the price is OK, but if we are buying new, I'm leaning towards either aluminum 80 for me and 63 for my son, or a steel 100 for me and a steel 80 for my son (or maybe steel 80s for both of us). My son wants something a little shorter and lighter -- and my back is not getting any stronger either these days.

Anyway, if I did buy new tanks, I did have a few questions for those experts that might be willing to lend a hand:

1. Any reason to buy aluminum (other than price)?
2. Any reason to buy low pressure steel (other than price)?
3. If I buy online, do I generally have to take it in to my LDS to get the valves put on, visual inspection, etc., or are they actually ready to fill? (I can call and ask, of course, but if the price is close, I would probably buy locally to avoid the hassle.)

Thanks to those that are willing to respond. I appreciate it.

 

[sealark]

Steel LP 85s or 72s Filled to 3000. Get your own compressor. Online the valves will be included. Steel tanks have less buoyancy changes from full to empty. Steel requires a boot because of rounded bottom Aluminum is flat bottom.

 

[RainPilot]

Get your own compressor.

While it it is nice to have your own compressor, the financials mean that, unless your local fill shop is REALLY far away and you are diving HUGE amounts, you are unlikely to break even.

Steel tanks have less buoyancy changes from full to empty.

Actually, the buoyancy swing in any tank is the gas weight difference between full and empty, ie a steel 80 and a aluminium 80 will have the same swing. The big difference between steel and AL is that AL tend to be positively buoyant when empty, so you need to add lead to your belt to compensate. Also, steel tanks of the same volume as an AL tank tend to be lighter when dry (assuming same pressure rating)

Thus, a steel tank will generally result in less total weight of your gear on land which is good for the back and knees.

The main reason to choose AL over steel is due to corrosion issues in salt, steel tanks require a bit more care in maintenance than an equivalent AL tank. If you are diving mostly fresh, I would find some steel tanks that fit your requirements and go from there.

 

[rhwestfall]

IMHO, steel is the best choice. You list Ohio as home, so cold water, and thick exposure suits. That means lots of lead can be part of the equation. Steel tanks lower that requirement. Now, the next thing is service pressure. Although I have not experienced it, some say they have run into troubles getting complete fills in 3443 psi tanks. If that were the case, lp steels (2400/2640 if + plus rated) become the option.

As to the issue with on-line purchases, that is going to be whatever the shop wants to do. You may "pay the penalty" of not buying from them, and be charged a VIP or something. Their compressor, their rules. Now, if you know another diver who has a transfill whip, and can bump a couple hundred psi into the tank from another after you put the valve on......

Keep in mind, there should be a very slight bit of lubricant used on the tank neck o-ring (silicone or oxygen compatible lube), and there are parameters as to what the tightness should be for the valve, so it should be done by someone who knows what they are doing. All that being said, it isn't rocket science either...

 

[2airishuman]

Anyway, if I did buy new tanks, I did have a few questions for those experts that might be willing to lend a hand:

Generally, your best bet is (steel) HP100s for an all around cylinder. Similar shape and weight compared to the AL80s you've been using, and greater capacity. HP80s are short and usually don't work well for people of average height or taller.

1. Any reason to buy aluminum (other than price)?

In your situation, no.

2. Any reason to buy low pressure steel (other than price)?

Some people like the overall tradeoffs that LP85s provide. That would be the only LP steel you would want to consider.

3. If I buy online, do I generally have to take it in to my LDS to get the valves put on, visual inspection, etc., or are they actually ready to fill? (I can call and ask, of course, but if the price is close, I would probably buy locally to avoid the hassle.)

I've only bought one cylinder new, and it was from DGX. It came fully assembled and had a VIP sticker. I was able to get it filled locally without another VIP. Some shops will insist on doing their own VIP in that situation but it's unusual.

Steel LP 85s or 72s Filled to 3000. Get your own compressor. Online the valves will be included. Steel tanks have less buoyancy changes from full to empty.

A compressor? For someone who's buying their first cylinder? Come on. Also, air weighs the same (1 pound per 13 cf) regardless of what material cylinder it's in, so the buoyancy changes are the same for cylinders with the same capacity.

 

[DavidFL]

I have recently bought tanks online (HP Steel 100s), and they were shipped with the valves separated from the tanks, so, yes, took them to the local LDS for a VIP and fill and they put the valves on since they would take them off for the VIP anyway.

I started a long time ago with Steel 72s; then had double steel 50s for awhile; have two aluminum 80s that I have kept in hydro and regular use now for 25 years, and now finally two steel 100s.

If I was starting today I would go for the steel HP 100; roughly the same weight as aluminum 80s; 20% more cu ft. when fully filled; easier to manage bouyancy changes. They are more expensive than AL, which you already know.

 

[Marie13]

Maybe HP80 steel for your son and HP100 for you if you can get them filled to the higher pressure.

I have HP80s. Work well for my 5'5" height. Much easier to deal with on land (on my back) than AL80s.

 

[RyanT]

You've gotten some good responses and I agree that (aside from cost) steel is the way to go. With both the steel 100 & 80, you'll be able to shed 5-6 lbs of lead compared to an aluminum 80. I've never run into a problem getting my high pressure tanks filled to their rated capacity. With a steel 100 though, if you did happen to get a short fill of only 3000 psi, you'll still have 87 cf of gas. That same short fill on a HP 80 will give you 70 cf of gas. An aluminum 80 filled to its rated capacity actually holds 77.5 cf.

 

[MrVegas]

Wow -- you guys are fast! I just took a look at this before I left for work, and tons of great replies already. Thanks so much! Steel it is, then -- and we have definitely noticed the buoyancy difference between that and aluminum. (We are wearing 7mm wetsuits.) Just have to decide on size then.

I really do appreciate the help. (I doubt I'll ever own my own compressor -- cost aside, I have enough trouble remembering to change my furnace filters.)

 

[Marie13]

If you're getting new steel tanks, Dive Right in Scuba has free shipping, even on tanks, through the end of the month.