130 tank

[palmm]

i have heard that steel 130 tanks are -12 lbs bouyant full of air, but how bouyant are they at 500 psi?

 

[sschlesi]

It depends on which specific 130 your are talking about, but about -10.5lbs full and -1lb empty for the E8-130.

Here is a whole chart filled with specs for different tanks. Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

I don't think the chart is very precise, a quick glance shows the e8-130 spec'd as swinging 9.5 lbs. for 130 cu. ft. of air, and the OMS 135 swinging just over 11lbs for 131 cu. ft. of air.

AFAIK a standard cubic foot of air weighs the same no matter what container it gets compressed into. The charts should give you a rough guide anyway.

 

[Graeme Tolton]

Should be around 2lb... however, this is without a valve, reg, bands, whatever else you want to put on it.

 

[palmm]

i guess the best question is, if you need less weight to descend. how much weight would you need to keep you from being to bouyant at your safety stop with your tank at 500 psi.

 

[RTee]

I get -11.7 lbs full and -2 lbs empty and this is with valve. Data comes from:

Scuba Cylinder Specifications from Tech Diving Limited - 928-855-9400

 

[Graeme Tolton]

i guess the best question is, if you need less weight to descend. how much weight would you need to keep you from being to bouyant at your safety stop with your tank at 500 psi.

What setup do you dive? It all depends on exposure suit, your body's buoyancy.. how much lead do you normally use with an al80? typically, you should lose 5-6lb of lead going from an al80 to a worthington x8 119 or 130

 

[Web Monkey]

i have heard that steel 130 tanks are -12 lbs bouyant full of air, but how bouyant are they at 500 psi?

The weight of the air in the tank is:

(0.0807Lbs/CuFt) * 130 CuFt = 10.49Lbs of air in the tank

This means that 500 PSI in a 3442PSI tank weighs 1.52396862 pounds, and bouyancy change from 3442 to 500 PSI would be (10.49 - 1.52) = 8.97Lbs.

This means that if the tank started out -12Lbs, it would be -12 + 8.97 or about 3.03Lbs negative @ 500 PSI

Note that tank specs sometimes include the valve and sometimes don't, which would change the results, and is based on a 3442 PSI tank. With an LP tank the numbers would be different.

Terry

 

[USCScubaboy]

I found this Excel spreadsheet in a previous post a while ago. It's not mine. Someone else posted it as an attachment a while back.

View attachment Tank Specs Master Sheet.xls

 

[NAM001]

As weight goes. I found out the hard way the charts do not reflect the correct weight of my faber tanks. the weights given (with valve) are not with valves used in the good old USA. they are Italian valves that weigh 1-2lbs more. Got this from the faber dealer when questioning scale readings. Seams that the tanks are used at a bit higher preaure than in the USA and hence have a heavier valve. The swing is correct (so-so) but the specific is in error for the USA. I suspect that non usa made tanks may all have the inaccuracy. has any one noticed that with other than faber tanks. maybe its a lp/hp thing.