Kidde mini tank Question

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georgeaustin
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Kidde mini tank Question

Sun Jul 30, 2017 3:25 pm

Guys,
- I'm going to look over a set of little 3AA / 1800psi / 4CM / AWK (Kidde) tanks tomorrow - The guy says they're 21 inch from bottom to neck face - are those the 38CF or 44CF? I doubt seriously if they're bigger than 44. They have the round bottom, looks like 3/4 NPST valve . . . (looks like) Not that the volume matters much but the last set of mini's I had, I thought were about 18 inch - - I can't look at them right now and measure them. The diameter is - I know 7.0 inch and in their bands, have the 8,0 inch center to center measurement.

Thanks. -

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ScubaLawyer
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Re: Kidde mini tank Question

Mon Jul 31, 2017 10:58 am

George, my Sportsways 1800 psi twin 38s are 19 inches long w/o valve. My twin Scubapro 45s (2250psi) are about 20 inches w/o valve. What you describe seems larger than 38s. I seem to recall SimonBeans has a set like the one you are talking about but could be mistaken. Guess i' m not much help. Just like to hear myself talk. :D

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georgeaustin
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Re: Kidde mini tank Question

Mon Jul 31, 2017 11:47 am

Thanks, Mark
I think they're probably 44's or maybe 50's - something like that. The internet has all the information (useless and otherwise) in the known universe - except - yep, WK steel tank specs from the 50's and 60's -
As a reference - My new Faber HP 80 is 21 inch from bottom to neck face - Catalina 45's, my mini doubles, are 18 inch. My LP 72 is 26" and my Scubapro branded Faber 80 (+/-) is 23.25 in. . . .

Of all these - that 21 inch Faber Hot Dipped trims me out the best (and looks the coolest) but that's diving the Poseidon SH Jetstream reg - how will it trim out when its lower with a VDH? - we shall see.

The only thing I'm pretty sure of is that the WK's at 21 inch are probably not the formerly ubiquitous Orange County 38's - or maybe it was Orange County 44's :?:
UPDATE: The WK's currently weigh in at 58.2 lbs (2) so I think they're probably full of some really nice southern California air from 1965 or so.
g

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georgeaustin
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Re: Kidde mini tank Question

Mon Jul 31, 2017 12:49 pm

Image

Here they are and does anyone know about that manifold? No J valve?

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ScubaLawyer
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Re: Kidde mini tank Question

Mon Jul 31, 2017 9:40 pm

Looks like an old Scubapro manifold on the ends. Don't know what's in the center. If it were me I'd put on a USD J-62 manifold instead to give it that vintage look. Might have an extra one laying around. Anyway, great find! Mark

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SurfLung
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Re: Kidde mini tank Question

Tue Aug 01, 2017 9:47 am

The only place I have seen specs for the mini-tanks is in the Basis Scuba book. Here's what I learned:

38s - These are 1800 psi USD tanks. Fill them 10% over (1980 psi) and they become 42s.

42s- These are 1880 psi Sportsways tanks. Actually 38 cf at 1880 and filling 10% over (2068 psi) gives 42 cf.

Discussion 1 - USD started with 1800 psi tanks and called them 38s. Sportways were 1880 psi and they advertised them as "42 cf". BOTH were 42 cf when filled 10% over. USD then changed their advertising to say "42 cf" to compete with Sportsways (IMHO).

Discussion 2 - Sportsways 1880 psi 42s have a little thicker steel which makes them heavier in the water. USD 1800 psi 38s are lighter and were actually advertised as being positively buoyant when empty... An advantage to the diver swimming home after his dive. I've heard 1800 psi 38s referred to in a negative light as "Butt Floaters".

Voit Steel 50s - These are about the same size but thicker steel at 2250 psi. Also, they aren't true 50 cf unless filled to 10% over (2475 psi). These have a reputation for being quite heavy in the water. But modern style divers seem to prefer heavy tanks.
All three of these "mini tank" types are about 19" tall.

Discussion 3 - My personal favorites are the 1800 psi 38s. These are buoyant enough that I have to wear a weight belt even when diving without a wet suit. As for the "butt floater" reputation... The bottom of the tanks are more buoyant than the top because the top has the heavier metal valve manifold. For me, a weight belt balances this and I swim in a level attitude.

Discussion 4 - My Sportsways 1880 psi 42s are a close second. I can't dive them without a wetsuit or horse collar BC, however. The make me negatively buoyant. I wear 6-8 lbs less on the weight belt (or no weight belt) when diving these tanks with a wet suit on.

Discussion 5 - These mini-tank twin setups are THE most perfect tank configuration. They are comfortable to wear. They position your double hose regulator perfectly on your back. And they hold PLENTY of air for most sport diving.

Discussion 6 - There seem to be a variety of sources for the 1800 psi 38s. I have one set made from war surplus Walter Kidd "Shatterproof USN" tanks. I have one set from USD AquaLung, And I just made up a recent set from two different brands of fire department tanks. One is Walter Kidde and the other is MSA. All three sets of 1800 psi 38s seem to have the same buoyancy characteristics. :)
Twin38vs42.jpg

l-r: WK 38s, USD 38s, Sportsways 38s
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SurfLung
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