How many pounds lift does a gallon of air have ??
Bob Botts
In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net> "Brad Wilson" <taxi...@bellsouth.net> writes:
> I am wondering or looking for a formula to tell me how many pounds of lift
>a given area has, such as a gallon jug. I could just go and put a gallon jug
>full of air in a pool and then weight it, but I thought this would be a
>better place to get an answer. You can just e-mail me the formula if you
>have one.
>Brad Wilson
>taxi...@bellsouth.net
A gallon of air displaces about 8 lbs of water. Therefore, a gallon container
filled with air should give you about 8 lbs of lift.
Cheers...Bob
Brad Wilson
Ken Kurtis
> I am wondering or looking for a formula to tell me how many pounds of lift a
A cubic foot of air will have a lifting capacity of 62.4 pounds in fresh water,
64.0 pounds in salt water. Figure the volume (in cf) of your container, know
the type of water you're in, multiply by the appropriate figure, and you've got
your answer.
Ken Kurtis
NAUI Instructor #5936
Co-owner
Reef Seekers Dive Co.
Beverly Hills, Ca.
IanV@here
kenk...@aol.com (Ken Kurtis) wrote:
>> I am wondering or looking for a formula to tell me how many pounds of lift a
>given area has . . .
>
>A cubic foot of air will have a lifting capacity of 62.4 pounds in fresh water,
>64.0 pounds in salt water. Figure the volume (in cf) of your container, know
>the type of water you're in, multiply by the appropriate figure, and you've got
>your answer.
>
>
Hi Ken
I was just thinking that perhaps the "lift" would be the weight
of the water displaced, less the "weight" of the gas at that pressure displacing the water.
;-) and of course if you had the gas under such pressure that
the density of the gas equalled the density of the water, then
the lift would be nil.
happy really deep diving
Ed Newberg
Brad Wilson wrote:
>
> I am wondering or looking for a formula to tell me how many pounds of lift
> full of air in a pool and then weight it, but I thought this would be a
> better place to get an answer. You can just e-mail me the formula if you
> have one.
>
> Brad Wilson
> taxi...@bellsouth.net
Easier to fill the jug with water and weigh that in air. Neglecting
the weight of the air itself, the bouyant force will be the weight
of the water minus the weight of the jug.
For rough figuring, Mom always said "a pint's a pound the world
around," which would give 8 lbs per gallon.
But you seem to want a more mathematical approach, so...
1 gal = 0.1337 cubic feet
According to ye olde Eshbach (3rd edition), fresh water weighs
62.4 lb / cf and salt water weighs 64 lb / cf.
Hence the weight of 1 gallon of fw is 62.4 * 0.1337 = 8.34 lb,
and 1 gallon of sw weighs 64 * 0.1337 = 8.56 lb.
Sonofagun! Mom was close! (Always listen to your mother, folks.)
Ed
--
"Only wimps die of natural causes."
=============================================
The opinions expressed herein do not necessarily
reflect those of my corporate masters. Yet.
Reply to email to:
G_Edward...@ccmail.orl.lmco.com
Rlongbo
Sea water weighs 64lbs ft3. One gallon is .1337 ft3.
64 times .1337=8.5 lbs
GregGarten
>In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net> "Brad Wilson"
><taxi...@bellsouth.net> writes:
>
>>a given area has, such as a gallon jug. I could just go and put a gallon jug
>>full of air in a pool and then weight it, but I thought this would be a
>>better place to get an answer. You can just e-mail me the formula if you
>>have one.
>
>>Brad Wilson
>>taxi...@bellsouth.net
Well boys and girls, we have two different opinions that differ quite a bit.
Will the right answer please step forward. If I remember my old physics
correctly, you do use the volume of the container, not the weight/mass of it.
Merl
then whats the boyancy of 80cuft. Al cylinder filled to 3000psi?????
--
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__________________________________________________
Lifes a journey that may end at any time.....So LIVE it up NOW!!!
__________________________________________________
Brad Wilson wrote in message ...
Ralph Brooker
GregGarten wrote:
>
> Well boys and girls, we have two different opinions that differ quite a bit.
> Will the right answer please step forward. If I remember my old physics
> correctly, you do use the volume of the container, not the weight/mass of it.
You need to know the container's volume AND weight:
Lift (= weight of liquid displaced by the object,
which is a function of the object's volume)
- Weight (weight of the object, including plastic and
anything in it such as air)
========
= Net buoyancy (overall upward force exerted by the object)
(My terminology). This is a universal formula; even works on Venus, if
you needed a lift bag while diving in molten sulfur under the reduced
gravity conditions. Here on earth, the weight of anything is just its
mass times the gravitational constant.
In anoher gratuitously extreme example, consider a steel scuba tank
which, compared to an Al tank of the same volume, has more weight, and
therefore less buoyancy. The compressed air inside weighs a few pounds
too, so it reduces the buoyancy at the beginning of the dive. As you
such out the weight of the air and blow it away as bubbles, the weight
of the tank decreases, and although the "lift" stays the same* the
buoyancy increases.
Ralph
* OK, the tank bulges a little less when empty - that's good for a few
micrograms. :)
Matthew E J Wood
Brad Wilson wrote:
>
> I am wondering or looking for a formula to tell me how many pounds of lift
> a given area has, such as a gallon jug. I could just go and put a gallon jug
> full of air in a pool and then weight it, but I thought this would be a
> better place to get an answer. You can just e-mail me the formula if you
> have one.
Simple formula - exactly one metric litre of air will lift exactly one
metric kilogram. That's the definition of a litre!
Cheers
Mat
--
,-----------------------------------------.------------------- __ ---.
| Dr Matthew Wood - ACRC Vision Group | _____ _____ | |_ |
| Room 2.08, Merchant Venturers Building | ==/ \=\__ \==| _\ |
| University of Bristol, Bristol, BS8 1UB | | Y Y \ / __ \_| | |
| 0117 954 5113 Mat....@bris.ac.uk | |__|_|__/(______/|___\ |
| http://www.cs.bris.ac.uk/~wood/ | ===BOOM======BOOM-CHA=== |
`-----------------------------------------"--------------------------'
Art Greenberg
In article <6akv44$d7n$1...@news1.epix.net>
"Merl" <N...@spam.here> wrote:
> then whats the boyancy of 80cuft. Al cylinder filled to 3000psi?????
Depends upon manufacturer, and will even vary somewhat between
cylinders from the same manufacturer. Generally, about -2 pounds
full. Empty, about +4.1 pounds.
Remove <nospam.> to reply:
Art Greenberg
nospa...@eclipse.net
Matthias Hebsacker
In article <34CDEE...@CanTheSpam.com>, Ed Newberg
<G_Edward...@CanTheSpam.com> wrote:
>But you seem to want a more mathematical approach, so...
>
>1 gal = 0.1337 cubic feet
>According to ye olde Eshbach (3rd edition), fresh water weighs
>62.4 lb / cf and salt water weighs 64 lb / cf.
>
>Hence the weight of 1 gallon of fw is 62.4 * 0.1337 = 8.34 lb,
>and 1 gallon of sw weighs 64 * 0.1337 = 8.56 lb.
>
Its those times when I realize how nice SI units are, where 1 liter of
water has simply a mass of 1 kg (negleting a few additional grams of salt
in sea water; the weight ). Maybe we europeans are just to stupid to handle
anything more difficult... ;-)
Regards;
Matthias
--
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Matthias Hebsacker Institute of Machine Tools
hebs...@iwf.bepr.ethz.ch and Manufacturing
ETH Zuerich
Phone +41 1 632 24 23
alt. +41 1 632 24 14 Swiss Federal
Fax +41 1 632 11 25 Institute of Technology
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Robert Wood
Merl wrote:
>
> then whats the boyancy of 80cuft. Al cylinder filled to 3000psi?????
Look here and search deja news
http://www.contraption.com/Scuba/tanks.htm
http://www.paradisedive.com/tspecs.htm
[\] Robert Wood
The St. Lawrence river - fresh, warm, visible diving.
mailto:rober...@mitel.com
Michael Pelletier
In article <34CDEE...@CanTheSpam.com>,
Ed Newberg <G_Edward...@CanTheSpam.com> wrote:
>
>1 gal = 0.1337 cubic feet
>According to ye olde Eshbach (3rd edition), fresh water weighs
>62.4 lb / cf and salt water weighs 64 lb / cf.
>
>Hence the weight of 1 gallon of fw is 62.4 * 0.1337 = 8.34 lb,
>and 1 gallon of sw weighs 64 * 0.1337 = 8.56 lb.
Actually, fresh water weighs approximately 62.42197253433209 pounds
per cubic foot. On the other hand, four liters of fresh water weigh
four kilograms, and four liters of salt water weigh slightly more than
four kilograms (around 4.1 kilograms).
Score one for the metric system!
-Mike Pelletier.
Ed Newberg
Matthias Hebsacker wrote:
>
> Maybe we europeans are just to stupid to handle
> anything more difficult... ;-)
>
NOW I get it! The metric system was developed as a concession to
the mathematically impaired, sorta like those special parking spaces
for the handicapped! ;)
DGoldan
Ah, back to Archimedes and his hot tub revelations. As he once stated, the
bouyancy of an object is equal to the weight of the water it displaces.
Therefore, in fresh water, a one gallon jug full of air displaces one gallon of
water, providing 8.33 pounds of lift. Slightly more in saltwater.
Michael Pelletier
In article <hebsacker-ya02408000R2701981736570001@news>,
Matthias Hebsacker <hebs...@iwf.bepr.ethz.ch> wrote:
>In article <34CDEE...@CanTheSpam.com>, Ed Newberg
><G_Edward...@CanTheSpam.com> wrote:
>
>>
>>According to ye olde Eshbach (3rd edition), fresh water weighs
>>62.4 lb / cf and salt water weighs 64 lb / cf.
>>
>>Hence the weight of 1 gallon of fw is 62.4 * 0.1337 = 8.34 lb,
>>and 1 gallon of sw weighs 64 * 0.1337 = 8.56 lb.
>
>water has simply a mass of 1 kg (negleting a few additional grams of salt
>anything more difficult... ;-)
Or what's more likely, we Americans are too stupid to stop wasting
our mental energy on a zillion different unit conversion factors. ;-)
But then, Matthias and I have already had this discussion.
-Mike Pelletier.
Mike Gray
Brad Wilson wrote:
>
> I am wondering or looking for a formula to tell me how many pounds of lift
> a given area has, such as a gallon jug.
A pint's a pound the world around.
A gallon jug (8 pints) gives 8 pounds lift. (yeah, yeah, I know, the
lift is 8.34 pounds less the weight of the jug in fresh water, and it's
impossible to find a gallon jug that displaces a gallon of water, etc
etc
regards
m
Mike Gray
GregGarten wrote:
If I remember my old physics
> correctly, you do use the volume of the container, not the weight/mass of it.
You remember wrong. Lift is displacement minus weight.
regards
m
Mike Gray
Matthias Hebsacker wrote:
>
> Its those times when I realize how nice SI units are,
Aye, the Yank couldn't get BSAC certified because he forgot the
conversion from bar to hectares!
regards
m
Doug Taylor
In article <34CDEE...@CanTheSpam.com>, Ed Newberg <G_Edward_Newberg@
CanTheSpam.com> writes
>For rough figuring, Mom always said "a pint's a pound the world
>around," which would give 8 lbs per gallon.
While my Dad always said:
"A pint of water
weighs a pound-and-a-quarter."
So a gallon of water, which is 8 pints, weighs 10 lbs. And that's the
lift available from a (light) gallon jug.
What's that? - Your gallons aren't as big as my gallons? Well, that's
another little ambiguity the original question left us with. Was it a
U.S. or U.K. gallon (or perhaps an Imperial one ;-)?
Metric system: un point...
Safe diving,
--
Doug Taylor mailto:do...@ivydene1.demon.co.uk
http://www.ivydene1.demon.co.uk/scuba.htm
Sub-Aqua Association UK - 'The Friendliest Divers in the World'
Philip B. Malter
b...@who.net wrote:
>
>
> rgrds billyw
DON'T LISTEN TO THIS SLIMEBALL, HE FLAMES,BULLSHITS,AND IMPUGNS PEOPLE'S
INTEGRITY,THEN SLITHERS AWAY LIKE THE SNAKE HE IS, WHEN HE IS CALLED TO
PUT UP OR SHUT UP-EVEN FOR CHARITY.
CHRISTOPHER ELIOT
Basically, lift is displacement minus weight. A gallon of distilled
water weighs 128 OZ (8 pounds), saltwater is a few percent heavier.
A gallon of vacume weighs zero, the weight of air can be ignored.
You can calculate the weight of air like this:
1 litre = 1.056 qt
22.4 litre = 1 mole @STP
23.654 qt = 1 mole @STP
1qt = 0.0422 mole
1 gallon = 0.169 mole @STP
Also, air is 80% N and 20% O2.
N weighs 14g/mole, O2 32g/mole.
14 * 0.8 + 32 * 0.2 = 20 g/mole for air
20 g/mole * 0.169 mole/gallon @STP = 3.38 g/gallon@STP
453g = 16oz (metric conversion)
28.3g = 1oz
0.0353 oz = 1g
3.38g/gallon * 0.0353 oz/g = 0.119 oz/gallon
So air weight 0.09% as much as water, which can be ignored.
-Chris Eliot
In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net>,
Brad Wilson <taxi...@bellsouth.net> wrote:
> I am wondering or looking for a formula to tell me how many pounds of lift
>a given area has, such as a gallon jug. I could just go and put a gallon jug
>full of air in a pool and then weight it, but I thought this would be a
>better place to get an answer. You can just e-mail me the formula if you
>have one.
>
>Brad Wilson
>taxi...@bellsouth.net
>
>
>
--
Christopher R. Eliot, Senior Postdoctoral Research Associate
Center for Knowledge Communication, Department of Computer Science
University of Massachusetts, Amherst 01003. (413) 545-4248 FAX: 545-1249
EL...@cs.umass.edu, <http://www.cs.umass.edu/~eliot/>
b...@who.net
In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net>,
"Brad Wilson" <taxi...@bellsouth.net> wrote:
|> I am wondering or looking for a formula to tell me how many pounds of lift
|>a given area has, such as a gallon jug. I could just go and put a gallon jug
|>full of air in a pool and then weight it, but I thought this would be a
|>better place to get an answer. You can just e-mail me the formula if you
|>have one.
from memory: A body wholly or partially immersed in a fluid is buoyed
up by a force equal to the weight of the fluid it displaces.
For practical purposes a gallon jug full of air and totally immersed
will be buoyed up by a force equal to the weight of a gallon of water.
rgrds billyw
gwh...@newsmail.tafensw.edu.au
> For rough figuring, Mom always said "a pint's a pound the world
> around," which would give 8 lbs per gallon.
>
>
> Ed
Aha but was Mum well-travelled ? Did she tell you that an Imperial gallon is
20% larger than a U.S. gallon? This gives you about 9.9 lbs per gallon,
so when in Britain you float that much higher in the water :)
--------------------------------------------------------------------------------
Geoff White
Sydney
Australia
IanV@here
"Brad Wilson" <taxi...@bellsouth.net> wrote:
> I am wondering or looking for a formula to tell me how many pounds of lift
>
>
>
Folks, am I missing something ? I would have thought that at
about 10 msw the volume of the air in the jug would be only
half a gallon - or is lift only measured exactly at surface
level ?
For lifting purposes should one not ask the depth at which the lift is required ?
I don't think Archimedies tub was that deep.
Steve L.
Ralph Brooker wrote:
> This is a universal formula; even works on Venus, if
> you needed a lift bag while diving in molten sulfur under the reduced
Ouch...the *extreme* in fire diving!
-Steve
John Brett
On 28 Jan 98 09:10:44 GMT, IanV@here wrote:
<snip>
>Folks, am I missing something ? I would have thought that at
>about 10 msw the volume of the air in the jug would be only
>half a gallon - or is lift only measured exactly at surface
>level ?
What you are describing is filling the jug on the surface, then
pulling it down to 10m. Fill it at 10m, and you put a gallon of air in
it (at 2ATA).
>For lifting purposes should one not ask the depth at which the lift is required ?
The depth affects the pressure (& therefore the mass) of the gallon of
gas you put into the jug. Its effect on the lift of the jug is minimal
The depth at which the lift is required is important for calculating
how much gas you need in the first place.
>I don't think Archimedies tub was that deep.
John Brett
Ed Newberg
gwh...@newsmail.tafensw.edu.au wrote:
>
>
> Aha but was Mum well-travelled ? Did she tell you that an Imperial gallon is
> 20% larger than a U.S. gallon?
I'm sure this must have some relation to Brit & Aussie beer consumption
rates...
Ed Newberg
IanV@here wrote:
>
> "Brad Wilson" <taxi...@bellsouth.net> wrote:
> > I am wondering or looking for a formula to tell me how many pounds of lift
>
> >
> >
> >
>
Yep. You're missing the assumption that the jug is rigid and does
not compress.
I would have thought that at
> about 10 msw the volume of the air in the jug would be only
> half a gallon - or is lift only measured exactly at surface
> level ?
>
> For lifting purposes should one not ask the depth at which the lift is required ?
Only if the lifting apparatus is compressible, like a lift bag. Rigid
containers will maintain the same bouyancy.
Robert Wood
But wait.... isn't a US pint 16 fluid ounces
and an Imperial pint 20 fluid ounzes ?
Robert Wood
Doug Taylor wrote:
>
> In article <34CDEE...@CanTheSpam.com>, Ed Newberg <G_Edward_Newberg@
> CanTheSpam.com> writes
> >around," which would give 8 lbs per gallon.
>
>
> "A pint of water
> weighs a pound-and-a-quarter."
>
> So a gallon of water, which is 8 pints, weighs 10 lbs. And that's the
> lift available from a (light) gallon jug.
>
> What's that? - Your gallons aren't as big as my gallons? Well, that's
> another little ambiguity the original question left us with. Was it a
> U.S. or U.K. gallon (or perhaps an Imperial one ;-)?
>
> Metric system: un point...
Yeah, very confusing. I'm a metric man trapped in
a 80% Imperial continent ;-^
I do everything in metric except dive.
Mike Gray
> > > Its those times when I realize how nice SI units are,
> >
> > Aye, the Yank couldn't get BSAC certified because he forgot the
> > conversion from bar to hectares!
>
> But wait.... isn't a US pint 16 fluid ounces
> and an Imperial pint 20 fluid ounzes ?
Yeah, but Canadian water has different density, being closer to the
North Pole, so it all works out the same.
regards
m
Mike Gray
Doug Taylor wrote:
> >Mom always said "a pint's a pound the world
> >around," which would give 8 lbs per gallon.
>
> While my Dad always said:
> "A pint of water
> weighs a pound-and-a-quarter."
C'mon, I've been in England and I know that a pound-and-a-quarter is 125
new pence.
regards
m
Charlie Gibbs
In article <6aocuc$a...@bgtnsc03.worldnet.att.net> omg...@worldnet.att.net
(Mike Gray) writes:
It's really hell for us Vancouver divers when we want to go down
to Washington to dive. Screws up our buoyancy something awful.
--
cgi...@sky.bus.com (Charlie Gibbs)
Remove the first period after the "at" sign to reply.
Lee Bell
IanV@here wrote:
> I was just thinking that perhaps the "lift" would be the weight
> of the water displaced, less the "weight" of the gas at that pressure
> displacing the water.
Correct, but potentially misleading. A gallon is a measure of volume
and a gallon container, as long as it's still a gallon container
(container not compressed, will always displace the same volume of
water.
> ;-) and of course if you had the gas under such pressure that
> the density of the gas equalled the density of the water, then
> the lift would be nil.
Correct again, but that would take a lot more pressure than you're
likely to see while diving . . . at least if you plan to return.
Lee
Kenneth A. Smith
Robert Wood wrote:
>
> Mike Gray wrote:
> >
> > Matthias Hebsacker wrote:
> > >
> >
> > Aye, the Yank couldn't get BSAC certified because he forgot the
> > conversion from bar to hectares!
>
> But wait.... isn't a US pint 16 fluid ounces
> and an Imperial pint 20 fluid ounzes ?
I would rather a pint of bitter than a gallon of Bud, Imperial or
othrwise...
And isnt the hectare the standard walking distance between bars in Wales
?... but you really mean the difference between hectare and Pubs dont
you ? :)
Ken
b...@who.net
In article <34CE89...@erols.com>,
"Philip B. Malter" <mal...@erols.com> wrote:
|>From: "Philip B. Malter" <mal...@erols.com>
|>Newsgroups: rec.scuba,rec.scuba.equipment
|>Subject: Re: How many pounds lift does a gallon of air have ??
|>
|>DON'T LISTEN TO THIS SLIMEBALL, HE FLAMES,BULLSHITS,AND IMPUGNS PEOPLE'S
|>INTEGRITY,THEN SLITHERS AWAY LIKE THE SNAKE HE IS, WHEN HE IS CALLED TO
|>PUT UP OR SHUT UP-EVEN FOR CHARITY.
Philip,
You seem to be incapable of handling the fact
that you were proven consistently wrong.
So... tantrums?
rgrds billyw
b...@who.net
|>
|>DON'T LISTEN TO THIS SLIMEBALL, HE FLAMES,BULLSHITS,AND IMPUGNS PEOPLE'S
|>INTEGRITY,THEN SLITHERS AWAY LIKE THE SNAKE HE IS, WHEN HE IS CALLED TO
|>PUT UP OR SHUT UP-EVEN FOR CHARITY.
Philip, you said you were a lawyer.
rgrds billyw
Mike Fischbein
Kenneth A. Smith (kasm...@ix.netcom.com) wrote:
You misspelled "whales" in the obligitory underwater
contents of your post...
mike
--
Mike Fischbein mike.fi...@csfb.com
Credit Suisse First Boston, 11 Madison Avenue, NY, NY
Any opinions expressed are mine only, and not necessarily
those of any other entity. They may not even be mine.
Jim.Gr...@cc.gatech.edu
Regarding "US or Imperial gallons ?", kasm...@ix.netcom.com wrote:
>
>I would rather a pint of bitter than a gallon of Bud, Imperial or
>othrwise...
I'd rather have a bottle in front of me, than a frontal lobotomy.
>And isnt the hectare the standard walking distance between bars in Wales?
That's possible - drunks do tend to stagger around all over the
place.
-JimG
--
Jim Greenlee (j...@cc.gatech.edu) Jryy abj lbh'ir tbar naq qbar vg!
Instructor, College of Computing Whfg unq gb xrrc svqqyvat jvgu vg
Georgia Tech, Atlanta, GA 30332 hagvy lbh oebxr vg, qvqa'g lbh ?!
Jason
> But wait.... isn't a US pint 16 fluid ounces
> and an Imperial pint 20 fluid ounzes ?
But the ounces are a different size too.
Jason
--
See www.volnay.demon.co.uk for trip reports on Spain
the Maldives, Barbados, Gran Canaria and Australia
Rudy Benner
bobb...@spectranet.ca (Bob Botts) wrote:
>In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net> "Brad Wilson" <taxi...@bellsouth.net> writes:
>> I am wondering or looking for a formula to tell me how many pounds of lift
>>a given area has, such as a gallon jug. I could just go and put a gallon jug
>>full of air in a pool and then weight it, but I thought this would be a
>>better place to get an answer. You can just e-mail me the formula if you
>>have one.
>>Brad Wilson
>>taxi...@bellsouth.net
>A gallon of air displaces about 8 lbs of water. Therefore, a gallon container
>filled with air should give you about 8 lbs of lift.
>Cheers...Bob
A US Gallon is 8 pounds. An Imperial Gallon is 10 pounds.
Rudy Benner
Timmins Ontario
ben...@onlink.net
IanV@here
Thanks Lee --- I thought it might be an open inverted container,
or perhaps a flexible container.... point taken.
Mark L Pidcoe
If your question refers to volume, then you will need to qualify it by
giving depth.
i.e. my B.C. provides for 52#'s of lift on the surface. Fill the bladder to
the same level at 33fsw and now my lift is 104#'s. As I rise toward the
surface the lift will be decreased by the bladder venting through
overpressure relief valves.
Lift is always referenced to surface values. Thus the measurement is that
of pure displacement. One gallon of air will displace one gallon of water.
Thus about 8#'s of sea water.
Did this provide more confusion?
Mike Gray
Mark L Pidcoe wrote:
> i.e. my B.C. provides for 52#'s of lift on the surface. Fill the bladder to
> the same level at 33fsw and now my lift is 104#'s.
>
Sure does, because it's wrong. Your fully inflated BC gives the same
lift REGARDLESS of depth.
regards
m
Tony Ghaffari
One gallon of Seawater weighs 8.6 lbs
One gallon of Freshwater weighs 8.0 lbs.
A cubic foot of Seawater weighs 64 lbs.
A cubic foot of Freshwater weighs 62.4 lbs.
1 litre of seawater weighs 1.03 kgs.
1 litre of freshwater weighs 1 kg.
Hope this helps,
Tony
b...@who.net wrote in message <885904388.910034@localhost>...
>In article <scdz.119$Hs1.4...@news3.mia.bellsouth.net>,
> "Brad Wilson" <taxi...@bellsouth.net> wrote:
>|> I am wondering or looking for a formula to tell me how many pounds of
lift
>|>a given area has, such as a gallon jug. I could just go and put a gallon
jug
>|>full of air in a pool and then weight it, but I thought this would be a
>|>better place to get an answer. You can just e-mail me the formula if you
>|>have one.
>
jf mezei
Mark L Pidcoe wrote:
> Lift is always referenced to surface values. Thus the measurement is that
> of pure displacement. One gallon of air will displace one gallon of water.
> Thus about 8#'s of sea water.
Yep, but a *volume* of one gallon of air will not weight the same at
depth compared to surface. So a gallon of air will provide less lift at
depth because that gallon will weight more, containing more air in it
(at higher pressure).
This assumes, of course, a flexible container (bladder). In a metal
container, a gallon of air would provide the same lift at surface and
depth since it would contain same number of molecules of air in same
volume container.
Prof. Vincent Brannigan
Mark L Pidcoe wrote:
>
> If your question refers to volume, then you will need to qualify it by
> giving depth.
> surface the lift will be decreased by the bladder venting through
> overpressure relief valves.
>
> of pure displacement. One gallon of air will displace one gallon of water.
> Thus about 8#'s of sea water.
>
no, you are not confusing, just wrong. you are describing the amount of
air it requires to inflate the BC, not the lift. The lift stays
constant if the BC is kept full, however the amount of air required to
inflate the BC at depth is related to the water pressure. as you
ascend, if the BC is full, it should vent or be vented.
Vince
Gordon in Austin
In article <34D505...@videotron.ca> jf mezei, @videotron.ca writes:
>Yep, but a *volume* of one gallon of air will not weight the same at
>depth compared to surface. So a gallon of air will provide less lift at
>depth because that gallon will weight more, containing more air in it
>(at higher pressure).
True, but a gallon of air at STP (room temp, 1 atmosphere) weighs about 5
grams, and water weighs about 8.5 lbs per gallon no matter what the
depth, so the lift at the surface is about 8.5 lbs (about 3860 grams)
minus 5 grams. At 33 feet, assuming the same volume (if you add air to
equalize the pressure), the density of the air about doubles, so a gallon
of air weighs about 10 grams. The lift is 8.5 lbs minus 10 grams. Not
much different. At 66 feet, 15 grams, etc. You'll have to go pretty deep
to make an appreciable difference.
Gordon in Austin
simon...@calwest.net
Mike Gray
simon&ka...@calwest.net wrote:
>
> ounces are ounces
Actually, an Avoirdupois ounce is 28.35 grams. A Troy ounce is 31.103
grams.
An ounce of gold weighs more than an ounce of feathers, although a pound
of feathers weighs more than a pound of gold...
regards
m
Nathanael Henderson
: ounces are ounces
ObDevil'sAdvocate: Unless it's a troy ounce. :-) (Which is a bit
heavier--12 troy onces to the pound.)
'Than
Michael Pelletier
In article <6bl77q$e37$1...@bell.pconline.com>,
And a troy pound weighs 80.364 grams *less* than an avordupois pound,
even though its ounces are larger.
-Mike Pelletier.
rmck...@unixg.ubc.ca
Lift is a function of the mass of water displaced. A gallon of water
weighs about 10 lbs (depending on which gallon standard you are using).
If the weight of the container can be neglected, then this is roughly
the amount of lift provided. Water is to a first approximation
incompressible, so assuming that the volume remains fixed, the lift
is independent of depth.
jf mezei
mck...@physics.ubc.ca wrote:
>
> Lift is a function of the mass of water displaced. A gallon of water
> weighs about 10 lbs (depending on which gallon standard you are using).
> If the weight of the container can be neglected, then this is roughly
> the amount of lift provided. Water is to a first approximation
> incompressible, so assuming that the volume remains fixed, the lift
> is independent of depth.
In the case of the BC, its lift is equal to the weight of the water it
displaces minus its own weight.
To displace a constant amount of water, the BC will need to be inflated to a
highwer pressure at depth compared to surface. Hence, the BC, containing more
air molecules at depth, will weigh more and hence provide less lift.
Denis Brisson
Robert the question returns to important things to worry about during
the non diving days!!!
>
> But wait.... isn't a US pint 16 fluid ounces
> and an Imperial pint 20 fluid ounzes ?
In this case shouldn't we be getting our beer in slightly larger
bottles??? Hmmmmm!!! Beeeeer!!!! Doh! No beer, we are diving
tomorrow!!!
Happy Bubbles!!!
D B
Oh Gawd! Rather than weight (;}), I'll SLAM this one.
Mole? Isn't that a British shrew? (grin)and the crowd Roars.
cave Softly,
dive Safely,
Have F-U-N !
db
CHRISTOPHER ELIOT wrote in message <34cdf...@rcfnews.cs.umass.edu>...
>Basically, lift is displacement minus weight...[snip] >22.4 litre = 1 mole
@STP
>23.654 qt = 1 mole @STP
>1qt = 0.0422 mole
>1 gallon = 0.169 mole @STP
Nicholas Marien
> >
> > I am wondering or looking for a formula to tell me how many pounds of lift
> > a given area has, such as a gallon jug. I could just go and put a gallon jug
> > full of air in a pool and then weight it, but I thought this would be a
> > better place to get an answer. You can just e-mail me the formula if you
> > have one.
> >
> > taxi...@bellsouth.net
> Easier to fill the jug with water and weigh that in air. Neglecting
> the weight of the air itself, the bouyant force will be the weight
> of the water minus the weight of the jug.
> For rough figuring, Mom always said "a pint's a pound the world
> 1 gal = 0.1337 cubic feet
> According to ye olde Eshbach (3rd edition), fresh water weighs
> 62.4 lb / cf and salt water weighs 64 lb / cf.
> Hence the weight of 1 gallon of fw is 62.4 * 0.1337 = 8.34 lb,
> and 1 gallon of sw weighs 64 * 0.1337 = 8.56 lb.
> Sonofagun! Mom was close! (Always listen to your mother, folks.)
> Ed
> --
> "Only wimps die of natural causes."
> =============================================
> The opinions expressed herein do not necessarily
> reflect those of my corporate masters. Yet.
> Reply to email to:
> G_Edward...@ccmail.orl.lmco.com
Your mother seems to be fantastic!
