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Gallons per Cubic foot

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chuck shaw
chuck shaw Member Posts: 584
in THE MAIN WALL
but can someone tell me how many gallons of water are in a cubic foot.

Thanks

Chuck

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  • paul lessard_2
    paul lessard_2 Member Posts: 192
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    hey chuck is it 2.31?

    > but can someone tell me how many gallons of water

    > are in a cubic foot.

    >

    > Thanks

    >

    > Chuck

    >

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 143&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Contractor"_/A_



  • paul lessard_2
    paul lessard_2 Member Posts: 192
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    hey chuck is it 2.31?

    nope not even close it's7.5
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,562
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    It's

    7.480519
    Retired and loving it.
  • chuck shaw
    chuck shaw Member Posts: 584
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    paul

    are you sure????

    Chuck

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  • chuck shaw
    chuck shaw Member Posts: 584
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    thanks dan

    i knew Paul wasnt right ;-)

    Thanks

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  • paul lessard_2
    paul lessard_2 Member Posts: 192
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    what? 7.5 was close

    how's the new gig?
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,562
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    Sloppy,

    right? ;-)
    Retired and loving it.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    Believe that's for "standard" water at 62°.

    If you're doing calculations like Mark Etherton a while back when he was computing heat delivered by his boiler to the system you have to compensate for the actual temperature of the water as its density changes with temperature.
  • chuck shaw
    chuck shaw Member Posts: 584
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    Starts on Monday

    I'll let you know.

    Chuck

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,379
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    which gallons?

    ...and just in case you need to know Imperial gallons instead of US gallons, multiply the US gallon figure by .83267.
    There; I finally found a use for that conversion!
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,562
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    Good thing

    it doesn't start tomorrow!
    Retired and loving it.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,562
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    Paul!

    I'm wrong too!
    Retired and loving it.
  • chuck shaw
    chuck shaw Member Posts: 584
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    actually....

    I really ready to go. I am looking forward to getting some calls from the wall. Just be nice, Guy, Rich and Jeff are also there as well.

    Chuck

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  • paul lessard_2
    paul lessard_2 Member Posts: 192
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    he heeehehhehehhee!

    I love the wall!!
  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
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    It depends

    upon the temperature! So...... Until you define the temperature, there is no correct answer(G).

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  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,562
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    But

    what if we made the box out of ice?

    Hmmmmm.
    Retired and loving it.
  • jerry scharf
    jerry scharf Member Posts: 159
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    what's density got to do with this

    a gallon (I'm taking the leap that you mean a liquid US gallon, not an Imperial gallon or a dry gallon) is a measure of volume. A cubic foot is a measure of volume. Here's something from an online dictionary about a gallon (from a 1913 websters:

    Definition:

    Gal"lon, n. [OF galon, jalon, LL. galo, galona, fr.
    galum a liquid measure; cf. F. jale large bowl. Cf. {Gill} a
    measure.]
    A measure of capacity, containing four quarts; -- used, for
    the most part, in liquid measure, but sometimes in dry
    measure.

    Note: The standart gallon of the Unites States contains 231
    cubic inches, or 8.3389 pounds avoirdupois of distilled
    water at its maximum density, and with the barometer at
    30 inches. This is almost exactly equivalent to a
    cylinder of seven inches in diameter and six inches in
    height, and is the same as the old English wine gallon.
    The beer gallon, now little used in the United States,
    contains 282 cubic inches. The English imperial gallon
    contains 10 pounds avoirdupois of distilled water at
    62? of Fahrenheit, and barometer at 30 inches, equal to
    277.274 cubic inches.



    Dan got it right, Paul get's a hand grenade point (as in close counts in...) I looked up the conversion in my CRC Handbook and it's 7.4805192

    All those years of unit checks in chemistry and physics actully pays off (I just won't think about the ROI.)

    happy new year,
    jerry
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    Density has everything to do with it...

    Density of water changes with temperature.

    It is the very reason that gravity systems work and the culprit behind "ghost" flow in modern systems.

    Water is the most studied substance on earth. It is also the ONLY substance familar in all forms: solid, liquid and gas.

    I also believe it is unique in that it decreases in density (increases in volume) when turning to a solid.
  • Jack, CVMS
    Jack, CVMS Member Posts: 81
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    Sorry, Mike

    jerry's right - density has nothing to do with it. A cubic foot of gasoline is still equivalent to the same 7.48... gallons as a cubic foot of water... as is mercury, as far as that goes. Density only comes into the equation if you are calculating the weight for a given volume.

    You are correct in your statement that water is unique in expanding with a drop in temperature - starting at approx. 37°F, as I recall.
  • jerry scharf
    jerry scharf Member Posts: 159
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    I'm answering the original question

    Mike,

    The question was converting between cubic feet and gallons. I stand by my statement that they are both units of volume, and thus there is a simple constant conversion.It's easy to get that cubic feet is a volume, and I included a definition of a gallon to show that it's also a volume.

    I agree that water is magical stuff in so many ways.

    jerry
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    You left something out...

    Original question was how many gallons of WATER in a cubic foot.

    Yes, gallons and cubic feet are both measurements of volume.

    But that gallon of WATER is defined at an extremely specific state. Change the state of that water and it will no longer occupy the volume of a gallon.

    You can either use this or let it bite you.
  • Steve Paul
    Steve Paul Member Posts: 83
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    How many gallons are in a cubic foot of water

    The original question never mentioned anything regarding a temperature change. Therefore, at any given, constant temperature the volumetric content of one cubic foot of water (or any other liquid) will always be 7.48 cubic feet. Some how I think this Nit has been picked to death.

    A HAPPY, HEALTHY AND PROSPEROUS NEW YEAR TO ALL!

    Steve Paul
  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
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    a-yup

    a nit picked with wit can give one a fit! A fit of laughter hopefully.

    Then again - perhaps it is a nit-wit that creates a hissy-fit for a bit. (Not meaning anyone here or in this thread - just a bit of word play)

    But true grit when picking nits can result in tid-bits that offset fits.

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  • Tom_22
    Tom_22 Member Posts: 108
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    Mass Is Constant, Weight Changes

    To be a little more definative, Density x Volume = Mass, but not necessarily Weight.

    The weight would depend on the gravitational force acting on it. For instance, it would weigh less on the moon but more on Jupiter. In outer space it wouldn't weigh anything, but all along the mass remains unchanged. If you are only concerned about the weight on earth, however, it will have the same value as the mass.

    TomBk
  • scrook_2
    scrook_2 Member Posts: 610
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    2.31 ft H2O per psi...

    2.31 feet of water is 1 pound/square inch (psi)
    also, a gallon of water weights ABOUT 8.35 pounds (all disclaimers about density vs. temperature, covered below, apply), and (just in case), a cubic foot of water weighs ABOUT 62.4 lbs (again all temperature & density disclaimers apply!)
  • bob_25
    bob_25 Member Posts: 97
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    PRICELESS

  • Guy_2
    Guy_2 Member Posts: 9
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    How about...

    a city water meter which measures cf; At my home incoming H2O temp in summer is around 65 and winter 38 deg., Does the volume of water increase after the meter once the warmer basement and such takes affect? nit picking is contagious!
  • jerry scharf
    jerry scharf Member Posts: 159
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    trying to get all the questions out

    Is there a special "gallon of water"? I come from a chemistry/physics world, and no such specialness is identified. Now not much is based on volume, and almost everything is based on the number of H2O molecules, which is proportional to mass. Density is the relation between volume and mass.

    Does the volume increase as the water warms above 38 degrees? For a given number of H2O molecules, either the volume or the pressure goes up as temp increases, can't say which without seeing the system.

    Does the number of nits relate to the number, mass or volume of wetheads? Is this ratio also dependent upon the wit of the nits, or does that matter not a whit?

    enjoying the end of our rainstorm in northern california,
    jerry
  • Tom_22
    Tom_22 Member Posts: 108
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    > a city water meter which measures cf; At my home

    > incoming H2O temp in summer is around 65 and

    > winter 38 deg., Does the volume of water increase

    > after the meter once the warmer basement and such

    > takes affect? nit picking is contagious!



  • Ted_4
    Ted_4 Member Posts: 92
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    Conversion Mania

    Hey Wallies, check out this site:

    www.metric-conversons.org

    They've got every conversion you might want - and more!
    Want to convert barrels(US) to cubic meters? It's there
    Want to convert kilograms to pennyweights? It's there, along with EVERYTHING else! Have fun!
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    At 38° you get about 62.42 pounds of water in a cubic foot.

    At 65° you get about 62.34 pounds of water in a cubic foot.

    Water bills are usually per 100 cubic feet so in the winter you are getting 6,242 pounds of water for each unit of billing and 6,234 pounds of water for each unit of billing during the summer.

    Water at 62° weighs about 8.3 pounds so in the summer you're getting about 1 gallon less of water per hundred cubic feet. Sorry--that's a bad way to put it. In the winter you're getting about 8.3 more pounds of water for 100 cubic feet than in the summer. If you took that 100 cubic feet of "winter" water and warmed it to the temperature of "summer" water you would have about one gallon more.

    100 cubic feet is about 748 gallons at 62°. That's an difference of about 0.00133% between summer winter. I rather suspect that the tolerance in the meter itself (measuring by the cubic foot) is significantly greater.

    These differences don't matter for casual calculations but they DO matter for many things.

    1) In a closed system there has to be room for expansion with changing temperature--thus we have compression/expansion tanks in hydronic heating systems. Remember that water is essentially incompressible.

    2) In an open/closed system like a domestic hot water tank, the small amount of difference can "work its way back" to the supply main/well by effectively moving "backwards". Add a backflow preventer that stops this however, and you have to start installing expansion tanks near the water heater less you overly stress the heater or even make the T&P start leaking or even "pop".

    3) If you're making calculations that involve a significant amount of water moving over a long period of time--like if you want to calculate BTUs moved through forced hydronic system--that tiny difference builds and can be the difference between impossibility and possibility.

    4) Gravity hydronic systems work solely because of this difference. It's great when you want to use it, but it can haunt you in other systems as it can be extremely subtle, difficult to "see", and difficult to completely stop.
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