How many tanks ?

[tbone1004]

only 3200? You're being far to gentle with them...

 

[Diver0001]

I want to start by saying I do not want this thread to become a debate over AL vs steel tanks or about training.

Currently I have 2 AL80 tanks and they have met my need. However, I'm going to start doing nitrox diving to and looking at adding stage bottles. I know to do nitrox I'm going to dedicate tanks to nitrox (under 40%). I have a plan to get to doubles with 2 stage tanks when I finish my Tec training. But want to buy smart on my way to that goal.

I was thinking of getting 2 larger tanks (110) to dedicate to nitrox will give me more bottom time on 60-90 ft dives, and in the future they could become a twin set. Then add 2 stage bottles, then add 2 more 110s convert to twins then add 2 more stage bottles.

What I was thinking...
2 AL 80 - air (already own)
2 ST 78 - nitrox stage (will need 4 for 2 dive charter)
4 ST 110 - 2 twin sets nitrox

Your Al-80's will make good stages. Build the back tanks around steel and you're golden.

Steel for stages really sucks imo because they are too negative.

R..

 

[Octopusprime]

The only reason I was thinking of starting with 2 large tanks that would become doubles is that right now I do not have a harness / wing for doubles. This way I could extend my dive. With the al80 at 100 ft before I would reach my NDL. I will have to check the height I'm short 6'7" so my gues is short fat tanks it is...

I do like the idea of buying doubles used. DRIS has a nice full doubles set I was looking at the shop the other day.

 

[MaxBottomtime]

Depending on which agency you get your training from, steel stages will either be frowned upon or not allowed. You'd be better off with aluminum 40s until you are making really big dives. Then you should use aluminum 80s. By the time you've spent a fortune on stages and doubles it will be time to realize you've spent way more than a rebreather costs.

 

[Dr. Lecter]

By the time you've spent a fortune on stages and doubles it will be time to realize you've spent way more than a rebreather costs.

It's ok, though, because you'll still need that whole herd of tanks for bailout on really deep/long CCR dives.

 

[Jack Hammer]

Around here you will find steel doubles are preferred due to helping offset the amount of lead needed in the colder water. Getting fills can be a real hassle in the area, as not all shops can/will fill you past 3000psi hot. I've had many a fill to 2700psi on my HP tanks. Now I drive to DRIS, 45miles each way, to avoid the BS I've often found in Chicago and get a reasonable fill.

You'll find that as you get more comfortable with tech gear your breathing rate will drop and you will get quite a bit of time from a set of doubles. I only use stages for very long or deeper dives. A single dedicated al40 for deco gas will cover quite a bit of diving and bottom time. Al80s make great stage/deco bottles for longer dives. It is better to take your time and get used to each piece of gear before adding more. More gear = more complexity and more to deal with if you have an issue. When you get doubles, practice diving with them at Haigh Quarry where you can walk out if you have any setup issues, better there by the road than turtled on the bottom of Lake Michigan.

 

[ajtoady]

I've started to use LP Faber 85's for deep dives in the 170-200 range and I have more than enough. I like them more than the my doubled Faber 100s and PST 100's. Plus I pump them up to 3200 also.

If you check it out, you really have not gained anything by pumping this tank, except for over stressing it. The cubic volume difference between your LP85 and a HP100 is .1 liters. The HP tank is made to take the pressure at 3442 psi on a regular basis. The LP tank is not and if you look at the weights of the tanks you will see a slight difference in empty weight. Another point being, did you change the valve to accept the higher operating pressure you are subjecting it to. I know, all minor things, but in this day and age, points that are looked at in an accident or event that went wrong.

 

[tbone1004]

I was hoping not to get into a LP vs HP discussion, but valves are valves, all modern valves are designed to take high pressure, if he's going that high which really isn't that high, it's only the burst discs that have to be replaced. When have you ever seen valves with different pressure ratings on them that were made in the last 20 years aside from the 7/8" necks?

LP85's are more analogous to HP120's than they are to HP100's, holding right around 113cf at 3500psi, the Worthington 85's are closer to HP100 specs, Fabers are not, and you'll note that among the Worthington tank specs, the LP85 splits the capacity of the 100 and 120's, and also splits the weight between them almost exactly. Same damn tanks. Too expensive to do otherwise, at least for that run. Faber has recently redesigned the alloy for all of their tanks, and they have all gotten a bit lighter and they all float like hell now. Oh, the Worthington 119 and LP95 are basically identical, the 119 is .2 inches longer and .1lbs heavier. If that isn't the same damned tank I don't know what is.

LP tanks especially the more modern 2400+ bottles have been subjected to multiple hydro's a week for decades and there has yet to be a documented tank failure, and I don't know of any LP bottles that have failed hydro, only VIP due to rust. Stop spreading that crap, if you want to pump your LP tanks all the way up, go for it, they aren't going to explode on you, just make sure the burst discs are at the right rating and you'll be fine.

 

[PfcAJ]

al80s for stages and deco bottles, an al40 for o2 deco is sweet.

lp85s (or whatever their 3442 equivalent is if you cant/wont overfill) are superb tanks for tech diving. lp104s (hp130s) for cave.

 

[ajtoady]

I was hoping not to get into a LP vs HP discussion, but valves are valves, all modern valves are designed to take high pressure, if he's going that high which really isn't that high, it's only the burst discs that have to be replaced. When have you ever seen valves with different pressure ratings on them that were made in the last 20 years aside from the 7/8" necks?

LP85's are more analogous to HP120's than they are to HP100's, holding right around 113cf at 3500psi, the Worthington 85's are closer to HP100 specs, Fabers are not, and you'll note that among the Worthington tank specs, the LP85 splits the capacity of the 100 and 120's, and also splits the weight between them almost exactly. Same damn tanks. Too expensive to do otherwise, at least for that run. Faber has recently redesigned the alloy for all of their tanks, and they have all gotten a bit lighter and they all float like hell now. Oh, the Worthington 119 and LP95 are basically identical, the 119 is .2 inches longer and .1lbs heavier. If that isn't the same damned tank I don't know what is.

LP tanks especially the more modern 2400+ bottles have been subjected to multiple hydro's a week for decades and there has yet to be a documented tank failure, and I don't know of any LP bottles that have failed hydro, only VIP due to rust. Stop spreading that crap, if you want to pump your LP tanks all the way up, go for it, they aren't going to explode on you, just make sure the burst discs are at the right rating and you'll be fine.

No debate, but check the specs on faber LP 85's. They are 13 liter volume. HP 120's are 15 liter volume. HP 100's are 12.9 liter.