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1 3/4" -vs- 2" water weight?

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  • 1 3/4" -vs- 2" water weight?

    I don't know how to figure this out, was hoping someone on here knows how.

    How much more does a charged 2" line weigh compared to a charged 1 3/4" handline?

    Were talking lightweight Ponn Conquest hose. Don't worry about the nozzle. I just want to know how much more each 50' length or charged 2" weighs compared to charged 1 3/4".
    Chris Shields
    Lieutenant / EMT
    Haz-Mat Technician
    East Syracuse Fire Dept
    Onondaga County, NY

  • #2
    make me think, ouchy

    Allllriiiigghhhhhtttyyyyy thennnnn---
    Each 50 foot lenght of hose is 600 inches long (50x12)
    1 3/4" diameter if true 1 3/4" i.d. (internal diameter)
    1.75 x 600 = 1050 cubic inces and
    2 x 600 = 1200 cubic inches
    a cubic inch of water weights 0.0361267 lbs.
    ergo (love that word, never get to use it) 1050 x 0.0361267 = 37.933 lbs. and 1200 x 0.0361267 = 43.352 lbs., guess you'll have to weight both of the hoses to see their difference, of course there will be variables, are the hoses equally dry, are they equally absorbent, your height above or below sea level, water temperature, ambient temperature, contaminants, using light or slippery water or foam, the pressure the hoses are flowing at, would be a little increase weight due to compression at higher pressures, guess the fitting might be a little heavier too, but I think about 4 1/2 to 5 lbs. is your answer.
    Good luck with whatever your researching...
    don't ya just hate a small aleck!!!LOL
    Last edited by CharlieRFDPres; 11-20-2003, 06:55 PM.
    (should now be CharlieRFD,past,Pres.), but I've had this screen name for so long, I'm keeping it..., besides I'm Deputy Chief now.


    • #3
      To calculate the difference in weights between hoses of any diameter you must add the difference in water weight to the difference in hose weight.

      You can get the hose weights from the manufacturer or weigh the hose yourself. Be sure to get the weight of coupled hose. Some manufacturers provide weights of uncoupled hose. The weight of the water absorbed by the jacket depends on the type of jacket and its construction. Typically, this should be minimal.

      The difference in the weight of the water in 50 feet of hose can be calculated from the following:

      WD = C (D^2 - d^2)

      WD = Weight Difference of the water per 50 feet
      C = Constant (Temperature dependent)
      D = Diameter of the larger hose
      d = diameter of the smaller hose
      ^2 = Square

      Although the temperature will make a difference, it is minimal.
      C = 17.025 for 40 F
      C = 16.968 for 80 F
      I suggest using C = 17.

      So, Take the difference in the square of the diameters and multiply by 17. Add this to the difference in the weights of the 2 hoses under consideration.

      For your case,

      WD = 17 (2^2 - 1.75^2)
      WD = 17 (4 - 3.06)
      WD = 15.9 pounds difference in water weight.

      Total weight difference = 15.9 + Difference in the weight of the hose.

      To calculate the weight of the water in the hose:

      Area = 3.14 {(D/12)^2}/4 (Sq.Ft.)
      Volume = Area X Length
      Weight = Density X Volume

      Density = 62.43 at 40F (Winter)
      = 62.4 at 50F
      = 62.37 at 60F
      = 62.3 at 70F
      = 62.22 at 80F (Summer)

      For 2" hose:

      Area = 3.14 {(2/12)^2}/4 (Sq.Ft.) = 0.0218 Sq.Ft
      Volume = 0.0218 Sq.Ft X 50 Ft = 1.09 Cubic Ft
      Weight = 62.4 X 1.09 = 68 pounds

      For 1.75" Hose

      Area = 3.14 {(1.75/12)^2}/4 (Sq.Ft.) = 0.0167 Sq.Ft
      Volume = 0.0167 Sq.Ft X 50 Ft = 0.835 Cubic Ft
      Weight = 62.4 X 0.835 = 52.1 pounds

      Difference in water weight = 68 - 52.1 = 15.9 pounds per 50 feet.

      How much the diameter of these hoses change with increasing pressure, I don’t know. Assume each hose increases in diameter by 10% from the nominal diameter. The weight difference between 1-3/4" and 2" hose would then be 19.3 pounds - 3.4 pounds more than using the nominal diameters.

      I think I got this right. If anyone finds a mistake, please provide the correction. Other factors which could affect the weight should not be of significance.

      I hope this helps.

      Jim Feld
      Fairfield, CA


      • #4
        Check Conquest Hose ID

        NFPA requires 1.75" hose to be a min of 1.75" ID. 1.75" Ponn Conquest is approx 1.9" ID. That is why the friction loss of conquest is much lower than other 1.75" hose..

        As for the weight difference.. (Assuming temp will be the same, to eliminate density differences)

        Area = Pi * raduis^2

        For Conquest
        Area difference = 3.14 (1^2-.95^2) = 0.306 sq in per in of hose
        For 50' (600 in) = 183.7 cu in of water in the 2" vs. 1.9" hose
        1 gal of water is 231 cubic inches
        Water weights 8.34 lbs per gallon...
        So (183.7*8.34)/231 = 6.63 lbs + weight difference of the hose

        For 1.75" ID
        Area difference = 3.14 (1^2-.875^2) = 0.736 sq in per in of hose
        For 50' (600 in) = 441.6 cu in of water in the 2" vs. 1.75" hose
        So (441.6*8.34)/231 = 15.9 lbs + weight difference of the hose
        Last edited by acamato; 04-27-2006, 01:57 PM.


        • #5
          Bigger not alwas better..

          Were looking at going back to 1 1/2 Line's. Most fire's a red line could put out what's on fire. But everyone think's a big line is better. Why not just pull a 2 1/2 for an attack line if you want alot of water. If your manpower can pull it, go with it. But if your company is low on manpower as is mine, Dont do it. Sorry im not a math person like the other guy's. Just putting in my 2 cent's.


          • #6
            I have a question for Jim and Charlie. They both did what appears to be the same calculation, but came out with significantly different answers.

            Charlie says 50 ' of 1 3/4" hose should weigh 37.9 lbs and 50' of 2" should be 43.5 lbs.

            However, Jim says those same dimentions are 52 lbs and 68 lbs respectively.

            I'm no math whiz and don't know the calculations off hand, but something ain't right here.
            If you don't do it RIGHT today, when will you have time to do it over? (Hall of Fame basketball player/coach John Wooden)

            "I may be slow, but my work is poor." Chief Dave Balding, MVFD

            "Its not Rocket Science. Just use a LITTLE imagination." (Me)

            Get it up. Get it on. Get it done!

            impossible solved cotidie. miracles postulo viginti - quattuor hora animadverto

            IACOJ member: Cheers, Play safe y'all.


            • #7
              Originally posted by CharlieRFDPres
              1.75 x 600 = 1050 cubic inces and
              2 x 600 = 1200 cubic inches
              a cubic inch of water weights 0.0361267 lbs.
              I think there is a problem with your calculation. To calculate volume you must mulitply area X length and you are simply mulitplying diameter and length. My calculations are

              1.75" = 1440 cu. in = 6.23 gal = 51.96lbs/50ft
              2" = 1884 cu in. = 8.16 gal = 68.05lbs/50 ft

              add that to the weight of a section of hose and you got what you are looking for.


              • #8
                If the actual ID of 1-3/4" Ponn Conquest is 1.9", what is the actual ID of 2" Ponn Conquest?

                Since the percent increase in the actual ID of 1-3/4" is 8.57% the actual ID of 2" would be 2.17", using the same % increase.

                The weight difference in water between the 1-3/4" and 2" hoses would then be 18.8 lbs.

                Does anyone know the actial ID of 2" Ponn Conquest? I check the website and found nothing.

                Also, I was sent an e-mail asking about the constant used in my calculation. It represents all of the numbers used to calculate the volume and weight. It is based on a 50 ft length of hose. If you want to base it on 100 ft, then use 34. The unit value is 0.34 lbs/ft. This is ONLY the weight of the water, not the hose.

                Weight of water in 100 ft of hose = 34 X D^2 (where D is in inches)
                Weight of water in 50 ft of hose = 17 X D^2 (where D is in inches)
                Weight of water per ft of hose = 0.34 X D^2 (where D is in inches)

                This is a shortcut and must be used within the limitations described.


                • #9

                  That's the rounded weight of water, using the nominal diameter.

                  I'm not really sure what the interior diameter of Ponn Conquest is, and how it's achieved.

                  Some hose, such as Angus' Hi-Vol line, expands under pressure. Their nominal 4" and 5" hose actually are 4.2" and 5.2" at operating pressure...one of the ways they get phenomenally better friction loss figures than their competitors in that class. By the way it lengthens slightly too -- which is why the line you laid straight down the road is all snaked out when you look at it after it's charged.

                  The Conquests' polyethlyene (I think that's it...) liner is slipperier than rubber (one way it varies from the charts found in most fire service reference books...which where created for the technology and hose construction of forty years ago), and it's also impregnated into the inner jacket.

                  Those charts are not accurate, unless you buy really heavy, really low bid fire hose. They're OK and close enough, but using figures from the manufacturer or ones you've developed in testing are best. Generally on small handlines, the friction losses are all fairly similiar, and the biggest reason to pay attention is if you flow test your hose, a wide variation from the charts your using probably indicates the liner has been damaged.

                  Supply lines, with higher flows and longer distances it becomes more important to understand the performance difference in regards to friction loss.

                  With handlines, I feel the more important differences is the dry weight (how easy is this hose to lay out?) and how easily the jacket and couplings slide (how easy is this hose to advance?) -- some fabric is very grabby (like nitrile hose), some couplings have right-angle edges that are more likely to snag then couplings whose edges have been rounded. For "stair pack" hose that's meant to be schlepped as 100' or 150' to work off standpipes or extend a handline on the ground, how tightly you can pack the hose is also important (so it fits in the bag, it's not jammed in so tight you're fighting to get it to lay out).

                  The traditional "double jacketed, rubber lined" fire hose has two jackets -- traditionally cotton, today usually a synthetic. That allows for damage to the outer jacket, while maintaining structural strength from the inner jackets.

                  The jackets exist protect and hold in place the liner. In traditional hose, the liner is a seperate, third layer.

                  In Ponn, it's integral with the inner jacket, so there is no third layer.

                  If the hose weighs (dry) like 1.75", and especially takes up the space in the hose tray that 1.75" does, sounds like 1.75" to me irregardless of how it performs when charged. If you're worried about the weight, use 1.5" for your small fires, and either 2" or 2.5" for your big flows.
                  Last edited by Dalmatian190; 04-29-2006, 05:24 PM.


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