Tank selection -- help!

[Hal]

My tank of choice has been AL 100 cf -- enjoy the extra air I get when compared to AL 80s.

Will be heading to a place where AL 100s are not available. Did find a place that rents Steel 109 cf tanks. Problem is that the AL 80s are rated to 3000 psi (or perhaps a little more) and the Steel 109s are rated to 2450 psi. I'm not sure how to compare, i.e., will the amount of air I get in these steel tanks be more than what I would get in AL 80s at 3000 psi? More than what I would get with the AL 100s at 3000? I assume that there is some mathematical formula that would help me compare but also assume it would be too easy just to multiply size by psi.

Help!

Thanks,

Hal

 

[JeffG]

My tank of choice has been AL 100 cf -- enjoy the extra air I get when compared to AL 80s.

Will be heading to a place where AL 100s are not available. Did find a place that rents Steel 109 cf tanks. Problem is that the AL 80s are rated to 3000 psi (or perhaps a little more) and the Steel 109s are rated to 2450 psi. I'm not sure how to compare, i.e., will the amount of air I get in these steel tanks be more than what I would get in AL 80s at 3000 psi? More than what I would get with the AL 100s at 3000? I assume that there is some mathematical formula that would help me compare but also assume it would be too easy just to multiply size by psi.

Help!

Thanks,

Hal

Hmmmmmmmm Is 80 cf less than or more than 109 cf???

 

[Hal]

In comparing tanks, and air availability, I do not know how (if at all) psi factors in. A 100 cf tank at 3000 psi has more air than a 80 cf tank at 3000 psi. I do not know, however, if a 100 cf tank at 2450 psi has more air than an 80 cf tank at 3000 psi. In the case at hand, more specifically, I do not know how a 109 cf tank at 2450 psi compares to 100 cf or 80 cf tanks at 3000.

 

[roakey]

The question was clear, we're amazed that your instructor didn't cover this.

A tank that holds 109 cf tank at 2450psi has 9cf more gas than a tank that holds 100cf at 3000psi.

You don't care about the pressure, only the capacity (at least on the West side of the pond).

So a steel HP 80 that holds 80cf at 3500 psi has exactly the same amount of air as an AL80 that holds 80cf at 3000 psi. 80cf=80cf.

Roak

 

[Groundhog246]

The tank size as expressed in CF is the volume of air at ambient (1ATM) that the cylinder holds at it's rated pressure. Note: Steel LP cylinders with a + stamped hydro can be filled to 10% over they're rated pressure so 2450+ can be filled to 2495 PSI. If originally sold as an LP109 with a +hydro, it holds 109CF at 2495PSI or about 100CF at 2450. I've a pair of LP72's, originally +, but not with subsequent hydros, so at they're rated pressure, they're about equivalent to an AL63.

So in short, if you rent an LP steel 109, it'll be the same or slightly more than an AL100 if both are filled to their rated pressure. Unless you're an air hog or your buddy also dives a 109, the extra air won't of much use though.

Note: a steel tank will be less buoyant than an aluminum, so you can probably leave a couple of punds off your weight belt or you'll be overweighted.

 

[perpet1]

My tank of choice has been AL 100 cf -- enjoy the extra air I get when compared to AL 80s.

Will be heading to a place where AL 100s are not available. Did find a place that rents Steel 109 cf tanks. Problem is that the AL 80s are rated to 3000 psi (or perhaps a little more) and the Steel 109s are rated to 2450 psi. I'm not sure how to compare, i.e., will the amount of air I get in these steel tanks be more than what I would get in AL 80s at 3000 psi? More than what I would get with the AL 100s at 3000? I assume that there is some mathematical formula that would help me compare but also assume it would be too easy just to multiply size by psi.
Help!
Thanks,
Hal

There is a tricky mathmatical equation.......

109 > 80

or if you get really technical you can do

80 < 109

 

[Groundhog246]

There is a tricky mathmatical equation.......

109 > 80

or if you get really technical you can do

80 < 109

:54: Today I took the high road and answered the question, instead of pointing out that our instructor/LDS covered that in OW class.

 

[The Fresh Prince]

The tank size as expressed in CF is the volume of air at ambient (1ATM) that the cylinder holds at it's rated pressure. Note: Steel LP cylinders with a + stamped hydro can be filled to 10% over they're rated pressure so 2450+ can be filled to 2495 PSI. If originally sold as an LP109 with a +hydro, it holds 109CF at 2495PSI or about 100CF at 2450. I've a pair of LP72's, originally +, but not with subsequent hydros, so at they're rated pressure, they're about equivalent to an AL63.

So in short, if you rent an LP steel 109, it'll be the same or slightly more than an AL100 if both are filled to their rated pressure. Unless you're an air hog or your buddy also dives a 109, the extra air won't of much use though.

Note: a steel tank will be less buoyant than an aluminum, so you can probably leave a couple of punds off your weight belt or you'll be overweighted.

Me thinks thou should check thine math.

 

[Groundhog246]

I don't see a flaw in my "math", however, I was tired and in the light of morning I do see the flaw in my numbers, should have been 2250, 2250+ and 2500 not 2450, etc.
To the original question an LP109 if originally + rated (109CF @ 2500PSI) will hold about 100CF @ 2250PSI.

 

[Diver0001]

There is a tricky mathmatical equation.......

109 > 80

or if you get really technical you can do

80 < 109

LLOOOOOLLL

Best laugh all week.

R..