Baby doubles (steel, ~ 55 cf)?

[two.crows]

Have a look at my baby doubles.

Nice! That's close to what I imagined. Glad to see they work for you.

Faber has 476 cu.in. cylinders on their site, that would be 7.8 L x 2640 psi (182 bar) = 1420 L = 50 cuf

Any particular reason one would prefer 45s over 50s or vice versa?

 

[Jimmer]

Any particular reason one would prefer 45s over 50s or vice versa?

I actually wanted the Faber 50's, but they seem to be pretty scarce compared to the 45's. I found one set used, but the fellow selling them wanted more for one of the 50's, than I paid for both of the 45's put together.

 

[Jimmer]

Two Crows, where in Canada are you located? If you happen to be local, let's go for a dive and you can try them out for yourself.

 

[rx7diver]

In the mid 1990's, I doubled up two OMS LP 45's using OMS bands and OMS modular valves with a short non-isolating manifold bar. Although they looked quite slick, they were too short to be practical (I couldn't easily reach the valves, and the tank bottoms rested in an uncomfortable position on my, um, bottom). I wore them only once, during a quarry dive. I still have the bands, valves, and manifold bar. I keep thinking that if I could find a used pair of the old Scubapro "Slim-line" 3300 psig 72's (sold in the late 1980's, if memory serves, at the same time Scubapro sold the shorter "Slim-line" 63), I might be able to double them up with this old hardware and have a nifty set of practical "baby doubles."

 

[two.crows]

In the mid 1990's, I doubled up two OMS LP 45's using OMS bands and OMS modular valves with a short non-isolating manifold bar. Although they looked quite slick, they were too short to be practical (I couldn't easily reach the valves, and the tank bottoms rested in an uncomfortable position on my, um, bottom). [...]"

According to the information I have, OMS LP-45s should be 23" long - about the same as an Al 80 or a PST 100 - are yours different?

Or did you have to wear them lower because of the manifold being closer to the back of your head?

 

[rx7diver]

A Luxfer Al 80 is approx 26" without valve or boot. A PST HP 100 (the original 3500 psig "Sherwood Genesis HP 100") is approx 24" without valve or boot.

 

[jscott099]

My dive buddy girlfriend is tall (long legs) and slender through the torso. Traditional AL 80's were too long for complete comfort. Also, she wanted to set up doubles for cave diving. She opted for the PST E7 80. These are the standard 7.25" diameter but much shorter at 20". The HP let's here get 3442 in each. At 28 pounds empty they are even lighter than AL and stay negative the entire dive. May not be applicable for what you want but I offer as a consideration.

 

[Jim Lapenta]

For a nice compact set of doubles it's hard to beat a set of lp72's. I love mine and at 3000 psi I've got 174 cu ft of gas on my back. With better buoyancy than HP 80's. I have two HP E7 80's that were the biggest mistake I ever made. Unless I go with 120's or something like that I'll stick with lp steels. I know I can always get a good fill and they trim out nice. BTW some shops won't pump over 3000 even in HP tanks. Cave country that's not an issue but a HP 80 at 3000 psi is only 69 cu ft.

 

[rx7diver]

This is an intriguing thread! I just looked at the Faber Web site. It lists a DOT- and TC-approved 2640 psig (working pressure = 2400 psig service pressure + 10%) cylinder which has a 6.76" OD and a 730 cu in WC, and weighs 29.3#. I haven't been able to get to other details about this cylinder yet (you have to register to access this info, and I'm still waiting for my registration to go through), but depending on the other characteristics of this cylinder (e.g., its length and buoyancy), two of these might make a neat set of "baby doubles." Thoughts?

(P.S. My quick calculations show that this cylinder has a capacity of 75.9 cu ft at its working pressure. Can someone confirm this?)

 

[dave4868]

This is an intriguing thread! I just looked at the Faber Web site. It lists a DOT- and TC-approved 2640 psig (working pressure = 2400 psig service pressure + 10%) cylinder which has a 6.76" OD and a 730 cu in WC, and weighs 29.3#. I haven't been able to get to other details about this cylinder yet (you have to register to access this info, and I'm still waiting for my registration to go through), but depending on the other characteristics of this cylinder (e.g., its length and buoyancy), two of these might make a neat set of "baby doubles." Thoughts?

(P.S. My quick calculations show that this cylinder has a capacity of 75.9 cu ft at its working pressure. Can someone confirm this?)

Looks right to me:

2640 / 14.7 = 180 BAR

180 x 730 = 131,102 cu in

131,102 / 1728 = 75.869 cu ft

Dave C