Difference in bottom time between LP77 and AL80?

[dsteding]

Tank Factor:

Rated volume/working pressure (in cubic feet per psi, but it is easier to think in terms of 100 psi, so multiply by 100):

In this case it is 2.9 cubic feet per 100 psi (77/2640)*100.

3.6* 2.9=10.5 cubic feet more, so 87 cubic feet.

Assuming a RMV of .75 and a depth of 60 fsw, this will give you another 4 minutes or so at depth.

 

[divinginn]

i figured clayjar would hit that one first,thanks for the info.

 

[Tamas]

Tank Factor:

Rated volume/working pressure (in cubic feet per psi, but it is easier to think in terms of 100 psi, so multiply by 100):

In this case it is 2.9 cubic feet per 100 psi (77/2640)*100.

3.6* 2.9=10.5 cubic feet more, so 87 cubic feet.

Assuming a RMV of .75 and a depth of 60 fsw, this will give you another 4 minutes or so at depth.

OR you can always use this page as well to get the *quick* answer http://www.spearfishing.org/bruces_tips/java/tankv.html

 

[H2Andy]

Because AL is more vulberable to overfill.

yeah... if i were a shop monkey and somebody brought me an AL tank and said, fill it up to 3500 psi ... i'd be like

right ...

who knows what that tank has been through? i sure as heck wouldn't trust it

it'd PROBABLY be ok, but it's much more of gamble

 

[in_cavediver]

Why not? Minimum burst pressure on a Luxfer Al80 is 7500psi.

There is a fundemental difference in how steel and Al tanks get thier strength. Steel tanks tend to be more elastic with larger stretch and recovery capability, Al tends to be more rigid. History has shown that some LP steel tanks can be grossly 'abused' regularly (3500-3800 in a 2640 tank) and still pass hydro for years. I would not want to routinely try the same in an AL tank.

 

[PhilEllis]

If interested, we have a pretty nice sale on these right now. Only $189, shipped to your door in the 48 lower states. Thanks.

Worthington LP7-77 - $189 Each

Phil Ellis

 

[ClayJar]

Just a tiny note, Phil, but in the little comparison table on the left column, for the Steel 77, the diameter has a comma "7,25 Diameter" instead of a period. (I'd assume you were going for the euro look, but while some people use a comma instead of a period to indicate the location of the decimal, I know of none who do so who also measure in inches. )

 

[H2Andy]

don't the Brits do it?

 

[salt h20]

an LP 77 rated at 2640 if filled to 3000 psi would yield 87.5 cf

 

[Rainer]

ok what is the cf of air @ 3000 lbs on a 77,im seriously thinking of getting a few.

Just so people realize this is some really easy algebra.

77/2640 = x/3000

Solve for x.