How many cylinders do you own?

[Miyaru]

0. Am I doing this wrong if I can't even convince myself that owning one tank has value? Those things are expensive and you still have to pay to get them filled and for maintenance.

Yes you are most certainly doing it wrong.

But there's a light at the end of that tunnel: DIR and it means: Doing It Right. Look it up, there's a section dedicated to DIR, where you can even find the fanatics and fundamentalists who survived the DIR wars several years ago. Don't be scared away when someone says you're gonna die as that's a pretty standard remark.

You are in the majority. I think the last data I heard at DEMA was something like 80% of ALL certified divers don't own even 1 tank.

I guess I'm compensating for that 80%

 

[Bob DBF]

0. Am I doing this wrong if I can't even convince myself that owning one tank has value? Those things are expensive and you still have to pay to get them filled and for maintenance.

Depends on how often you dive, location of fill station, what type of diving you do, and your convenience.

In my case the fills were a thirty minute drive in the wrong direction, and the shop wasn't open until after I needed to be at the water. So I needed at least two tanks, more likely three for my beach dives. Paying for three days rental for a days diving, two if I rushed back, makes the purchase of tanks cheaper. Also, I have never bought a new tank, unless one counts the LP95, which had a year and a half off its hydro, and the shop discounted substantially.

I had a remote lake with no fill station for hours of driving each way. I'd take up 9 or 10 tanks for a long weekend of diving, not counting the pony. Granted some of the tanks were old steel 72s, but I wasn't diving deep with them. The 72s were very cheap or free


Most of the time I have 4 or 5 tanks in hydro and viz, I just have the others done when I am going to use them in the foreseeable future.

2 - MP 120 Faber
1 - HP 100 (3442)
1 - LP 95
2 - AL 80
1 - vintage 72 doubles
5 - old steel 72s (I have the parts to make two more sets of vintage doubles.)
1 - AL 19 pony

This cost me around $800 over 30 years, even if I add in the $200 for the two bad alloy tanks I picked up over 40 years ago that went to the great reef in the sky, it's still not bad for the time I've had tank storage available.

 

[Steelyeyes]

Three. Two AL 80s and an AL 19 in case I ever decide I need a pony. I may one day buy an AL 100 (or 15 liter) to hunt lion fish.

 

[rx7diver]

How many cylinders? Fifteen. But some of them really need to find a new home that will take care of them.

2 x HP 80 (3,500 psig). My first tanks. I dive these local, with my Scubapro SSJ. They pack quite nicely in my FD RX7.

1 x Steel 72 (2,250). A couple of years ago I traded a brand new, once-used Al 80 for this! It almost immediately became (and remains) my favorite tank to use local, with my SS Freedom Plate and 3/2 O'Neill jumpsuit. I need a second '72. (I actually traded a second new Al 80 for a second '72, but that '72 turned out to be questionable.)

1 x OMS (Faber) LP 66. I use this with my VDH-improved DA Aqua Master double-hose regulator and VDH backplate, local, and 3/2 O'Neill jumpsuit. Maybe I need a second one of these, too.

2 x HP 120 (3,500). These were manifolded and used for Great Lakes extended range diving. I broke them apart a few years ago. They are very seldom used anymore.

3 x OMS LP 46. These were my first deco cylinders. They sat unused until I began using them when introducing my then-young children to scuba. Two of these 46's are about to be doubled-up using a single-outlet J-valve manifold, for use with my DA Aqua Master.

1 x OMS LP 120. An experiment that didn't pan out. (What a pig!!) Used once (and probably never again). I need to get rid of it.

3 x Al 6. These are stickered and were used as Argon bottles for Great Lakes extended range diving. I need to get rid of these.

2 x Al 40. These were my second deco cylinders. I need to get rid of these.

So, as someone earlier in the thread mentioned, often a diver will have different cylinders for different uses.

rx7diver

 

[Marie13]

@rx7diver

Used HP100s are like unicorns here in the Midwest. They go very quickly when they are for sale. Even better if they take the 3/4” modern valves.

 

[Bob DBF]

Even better if they take the 3/4” modern valves.

3/4 is a modern valve compared to 1/2 valves, but the 7/8 is a newer standard than both, made for 3500# and greater pressure tanks, even though those tanks are no longer being made and haven't been made for quite a while.

HP 100 - 3/4 valve - 3442# service
HP 100 - 7/8 valve - 3500# service

 

[grantctobin]

4x PST LP120 10/70
2x Faber LP85 18/45
2x Faber LP50 32%
5x AL80 16/50 (oops), 18/45, 35/25, 50%, O2
3x AL40 O2
2x HP15 O2
1x AL13 suit
2x AL6 suit
Could use a few AL80 30/30 bottles but that’s what friends are for

 

[OTF]

12

 

[rx7diver]

3/4 is a modern valve compared to 1/2 valves, but the 7/8 is a newer standard than both, made for 3500# and greater pressure tanks, even though those tanks are no longer being made and haven't been made for quite a while.

HP 100 - 3/4 valve - 3442# service
HP 100 - 7/8 valve - 3500# service

And, for newer/young divers here, if I am not mistaken, the (old) 1/2" NPT valve does not use a tank-to-valve O-ring, but, instead, uses Teflon tape and is "squeezed" into the tank threads using a chain vise and a big/long wrench (for leverage).

EDITED: I looked but couldn't confirm what I wrote about carbon steel vs. chromoly, so I edited it out.

(Recalling this from ancient memory, so please correct as necessary.)

rx7diver

 

[Bob DBF]

And, for newer/young divers here, if I am not mistaken, the (old) 1/2" NPT valve does not use a tank-to-valve O-ring, but, instead, uses Teflon tape and is "squeezed" into the tank threads using a chain vise and a big/long wrench (for leverage).

There were some manufacturers that started using 1/2 NPS, but the 3/4 NPS used by others became the standard, back when the 2250# service steel 72 was the standard tank.

The 7/8 UNF valve with DIN 300 fitting was mandated for Scuba tanks 3500# service, and greater, later when higher pressure tanks were being produced.