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  • #31
    Re: Here is one for you math nuts

    I used slightly different method to arrive at roughly the same result,
    I got 30.6838 PSI

    .707*100' = 70.7 feet WC
    .434 *70.7 = 30.6838 PSIG



    Originally posted by Devine Plumbing View Post
    If we use the pythagorean theorema^2 + b^2 = c^2 and the pipe is at a 45 degree angle making a = b or 2X^2 = 10000
    x^2 = 5000
    height = 70.71 ft

    Now convert height into mm using the following conversions

    70.71 ft x 12 in/ft x 25.4 mm /inch = 21552.408 mm

    convert mm H20 to mm Hg using the specific gravity of mercury 13.6

    21552.408 x 1mm Hg/13.6 mm H2O = 1584.736 mm Hg

    1584.736 mm Hg x 1 atm/760mm Hg = 2.085 atm

    2.085 atm x 14.7 psi/1 atm = 30.650 psi roughly
    "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
    John Ruskin (1819 - 1900)

    Comment


    • #32
      Re: Here is one for you math nuts

      Yea I had a brain fart...
      70.71' is the head pressure...
      411 Plumb Appliance Stimulus Package

      Comment


      • #33
        Re: Here is one for you math nuts

        Turns out its 294' to the actual clog. Well, If thats what you'd call it.
        Thats the point that caused a series of BULL $HIT.
        What a mess. Right now I have to decompress before I post pics etc.
        9am-5:15pm all but maybe an hour Snaking up,down, this head, that head, from this point, and that point.
        ALL FOR NOTHING
        INSIGHT PIPE is now Maine Drain Serving most of ME with no charge for travel! 207-431-6232 is nolonger a working # our NEW # is 207-355-1476
        Sewer main snaking (roto rooting). Sink clogs. Sewer backup. Pipe inspection/locating. No Dig trenchless repair. Root clog removal.We are NOT to replace your local Plumber, as we do not do plumbing. WE ARE YOUR DRAIN CLEANING EXPERTS!!! www.sewermaine.com waterville winslow bangor augusta skowhegan fairfield pittsfield oakland

        Comment


        • #34
          Re: Here is one for you math nuts

          sounds like you got a tough one.

          What is it a line running down a hill or what?? The suspense is killing us!!

          Comment


          • #35
            Re: Here is one for you math nuts

            Originally posted by NHMaster3015 View Post
            If the pipe is 100' long ( stand it up, vertical ) then at 45% it would be 1/2 that or 50'
            NO!

            the 100' length of pipe represents the hypotenuse of a 45ยบ right triangle. the two adjacent sides of such a triangle can found by dividing the 100 feet by the square root of two. answer = 70.72 feet. That is the pressure head.

            Since you have approx. 44 PSI per hundred feet, 70 feet gives you a head pressure of approx. 31 PSI.

            Comment


            • #36
              Re: Here is one for you math nuts

              If I can assume that the 70.71 feet is the actual vertical height of the 4" pipe, the pressure would 30.61psi.

              The diameter of the pipe isn't a factor.
              Frequently asked questions about pumps and tanks.

              Comment


              • #37
                Re: Here is one for you math nuts

                The diameter of the pipe does not matter as far as pressure head goes.

                If you are wondering how much pressure the plug is holding back then you will need to know the ID of the pipe.

                Comment


                • #38
                  Re: Here is one for you math nuts

                  Originally posted by G3sprinklers View Post
                  The diameter of the pipe does not matter as far as pressure head goes.

                  If you are wondering how much pressure the plug is holding back then you will need to know the ID of the pipe.
                  Your first statement is correct the second one is wrong.

                  The pressure is determined by height alone the diameter determines how much you have coming at you...

                  While a 1 1/2" opening at 31-psi could be ugly...

                  A 8" opening at 31-psi is way way worse....
                  411 Plumb Appliance Stimulus Package

                  Comment


                  • #39
                    Re: Here is one for you math nuts

                    Are you sure??

                    Agree with what you have coming at you, that is volume.

                    Lets just say you have a piece of tubing that is 100 feet tall and filled with water, ID of 0.25 inch (you can cover that with you thumb).
                    Now same set up with ID of 3 inch (you should be able to cover that with the palm of you hand)

                    The pressure head is the same, right?

                    Which is easier to hold back? and why? (we are just talking static pressure not velocity pressure).

                    Is there something different going on with the suface area of the plug?

                    What about the weight difference in the water, in volume?

                    Would there be any difference in the force required to hold it back if there was a 0.25 inch orifice at the bottom of the 3 inch pipe (pressure head would be the same I know)?

                    Why is presure expressed in a weight per surface area configuration?

                    Educate me please. (I am not trying to be a smart @ss here).

                    G3
                    Last edited by G3sprinklers; 03-08-2010, 02:06 PM.

                    Comment


                    • #40
                      Re: Here is one for you math nuts

                      We need an Engineer to explain all this to us. I'm no expert, gut PSI is simply expressed as pounds per square inch. I guess if you have a lot of square inches on the same flat surface regardless how tall the pipe is, the pressure is the same at each and every square inch. They can't be added together though.

                      Now that I think about it, you couldn't cover the 4" with your thumb anyway. I think I have just stumbled upon the answer.
                      Frequently asked questions about pumps and tanks.

                      Comment


                      • #41
                        Re: Here is one for you math nuts

                        Gene I thought you were going to post up some pics of this job.

                        We want to see how it all turned out.

                        G3

                        Comment


                        • #42
                          Re: Here is one for you math nuts

                          Are you sure??
                          not saying I am correct so check my figures and thinking

                          Agree with what you have coming at you, that is volume.
                          And once it gets to moving velocity pressure will come into play and this can be measured with a pitot tube

                          Lets just say you have a piece of tubing that is 100 feet tall and filled with water, ID of 0.25 inch (you can cover that with you thumb).
                          surface area of plug (or cross sectional area of the pipe) = (pi)(r squared)
                          = (3.14159)(0.125" squared)
                          = 0.049 sq. inches

                          volume = (area)(height)
                          = (0.049 sq. in.)(1200 in.)
                          =58.8 cubic inches

                          weight of the water = 0.0361 pounds / cu. in.
                          = (58.8 cu. in.)(0.0361 lb / cu.in.)
                          = 2.12 pounds

                          pressure head = (height of water column in feet)(0.434 psi / foot)
                          = (100 feet)(0.434 psi / foot)
                          = 43.4 pounds per sq. inch

                          Now same set up with ID of 3 inch (you should be able to cover that with the palm of you hand)
                          area of plug = 7.069 sq. in.
                          volume = 8,482.8 cu. in.
                          weight of water = 306.22 pounds
                          pressure head = 43.4 psi

                          The pressure head is the same, right?
                          right

                          Which is easier to hold back? and why? (we are just talking static pressure not velocity pressure).
                          the 0.25" tube, takes less pressure to overcome the weight of the water

                          Is there something different going on with the suface area of the plug?
                          head pressure is the same, so why is it harder to hold back the 3 inch tube

                          pressure on the face of the plug
                          area of 0.25" tube = 0.049 sq. in.
                          head pressure = 43.4 pounds / sq. in.
                          = (0.049 sq. in.)(43.4 lb. / sq. in.)
                          = 2.12 pounds

                          area of 3" tube = 7.069
                          head pressure = 43.4
                          = (7.069)(43.4)
                          = 306.7 pounds

                          What about the weight difference in the water, in volume?
                          difference in weight, 2 compared to 306

                          Would there be any difference in the force required to hold it back if there was a 0.25 inch orifice at the bottom of the 3 inch pipe (pressure head would be the same I know)?
                          the pressure required to hold it back would be the same for the 0.25" plug reguardless of the size of the pipe diameter above.

                          Why is presure expressed in a weight per surface area configuration?
                          it is complicated to explain

                          Educate me please. (I am not trying to be a smart @ss here).
                          I could still be wrong

                          G3

                          Comment


                          • #43
                            Re: Here is one for you math nuts

                            Entire service was dug and replaced. Several problems where found.
                            I have a pretty good video of a poo ooze but my cpu is acting up and won't load all the pics and vid off the sd card.
                            I'll post about it when I get the time, it's a long story.
                            First time I've ever felt truly defeated by a damn pipe
                            INSIGHT PIPE is now Maine Drain Serving most of ME with no charge for travel! 207-431-6232 is nolonger a working # our NEW # is 207-355-1476
                            Sewer main snaking (roto rooting). Sink clogs. Sewer backup. Pipe inspection/locating. No Dig trenchless repair. Root clog removal.We are NOT to replace your local Plumber, as we do not do plumbing. WE ARE YOUR DRAIN CLEANING EXPERTS!!! www.sewermaine.com waterville winslow bangor augusta skowhegan fairfield pittsfield oakland

                            Comment


                            • #44
                              Re: Here is one for you math nuts

                              Are you sure??
                              not saying I am correct so check my figures and thinking

                              Agree with what you have coming at you, that is volume.
                              And once it gets to moving velocity pressure will come into play and this can be measured with a pitot tube

                              Lets just say you have a piece of tubing that is 100 feet tall and filled with water, ID of 0.25 inch (you can cover that with you thumb).
                              surface area of plug (or cross sectional area of the pipe) = (pi)(r squared)
                              = (3.14159)(0.125" squared)
                              = 0.049 sq. inches

                              volume = (area)(height)
                              = (0.049 sq. in.)(1200 in.)
                              =58.8 cubic inches

                              weight of the water = 0.0361 pounds / cu. in.
                              = (58.8 cu. in.)(0.0361 lb / cu.in.)
                              = 2.12 pounds

                              pressure head = (height of water column in feet)(0.434 psi / foot)
                              = (100 feet)(0.434 psi / foot)
                              = 43.4 pounds per sq. inch

                              Now same set up with ID of 3 inch (you should be able to cover that with the palm of you hand)
                              area of plug = 7.069 sq. in.
                              volume = 8,482.8 cu. in.
                              weight of water = 306.22 pounds
                              pressure head = 43.4 psi

                              The pressure head is the same, right?
                              right

                              Which is easier to hold back? and why? (we are just talking static pressure not velocity pressure).
                              the 0.25" tube, takes less pressure to overcome the weight of the water

                              Is there something different going on with the suface area of the plug?
                              head pressure is the same, so why is it harder to hold back the 3 inch tube

                              pressure on the face of the plug
                              area of 0.25" tube = 0.049 sq. in.
                              head pressure = 43.4 pounds / sq. in.
                              = (0.049 sq. in.)(43.4 lb. / sq. in.)
                              = 2.12 pounds

                              area of 3" tube = 7.069
                              head pressure = 43.4
                              = (7.069)(43.4)
                              = 306.7 pounds

                              What about the weight difference in the water, in volume?
                              difference in weight, 2 compared to 306

                              Would there be any difference in the force required to hold it back if there was a 0.25 inch orifice at the bottom of the 3 inch pipe (pressure head would be the same I know)?
                              the pressure required to hold it back would be the same for the 0.25" plug reguardless of the size of the pipe diameter above.

                              Why is presure expressed in a weight per surface area configuration?
                              it is complicated to explain

                              Educate me please. (I am not trying to be a smart @ss here).
                              I could still be wrong

                              G3
                              Man, I ain't arguing with all that math.

                              I think we are getting PSI and weight confused.
                              Frequently asked questions about pumps and tanks.

                              Comment


                              • #45
                                Re: Here is one for you math nuts

                                Originally posted by Redwood View Post
                                Your first statement is correct the second one is wrong.

                                The pressure is determined by height alone the diameter determines how much you have coming at you...

                                While a 1 1/2" opening at 31-psi could be ugly...

                                A 8" opening at 31-psi is way way worse....
                                He should have said the amount of force acting on the plug (or cap or whatever), not pressure. To calculate the force you need the pressure and the area subjected to that pressure.
                                "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
                                John Ruskin (1819 - 1900)

                                Comment

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