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Hydraulic Chart for 105' Aerial with 1250GPM Master

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  • Hydraulic Chart for 105' Aerial with 1250GPM Master

    Does anyone out there have a hydraulics cheatsheet for a 105' Quint? Anyone have any tips on pumping a Quint?

  • #2
    Developing a friction loss table for an aerial

    celtool: Looks like no one wants to tackle this problem. I won't either, but can make some suggestions. Beg, borrow or steal a pitot gauge.
    1. Place a standard 2" solid bore master stream device on the aerial, making sure that the proper stream shaper is in place before attaching the 2" tip.
    2. With the Quint properly supplied from an adequate source, the basket elevated at about 45 deg. (about 78 ft. elev) and the ladder fully extended. (Be sure you are not exceeding the limits for load) Flow the nozzle and have the pump operator gradually increase the discharge pressure until the pitot gauge in the tip stream reads 70 psi (about 1000 gpm)
    3. record the engine discharge pressure and then subtract the following: 70 psi nozzle pressure and 34 psi elevation pressure (0.435 x 78 ft.). The friction loss at 1000 gpm will be the difference. Example: If the E.P. were 153 psi then 153 - (70 + 34) = 49 psi friction loss
    4. Since friction loss follows the formula Fl = K * L * Q * Q (where Q is in 100's of gpm's) and both K & L are constants. Then substituting and solving we get K * L = Fl / Q * Q
    In our example K * L = 49 / 100 or the constant is about 1/2. (Z)
    5. Develop a friction loss table for the device as follows: (At "Z" = 1/2 ) 1 1/2" ( 603 gpm ) = 18 psi ; 1 3/4" ( 813 gpm ) = 33 psi; 2" ( 1080 gpm ) = 58 psi ; 500 gpm = 12.5 psi ; 750 gpm = 28 psi ; 1,000 gpm = 50 psi. Don't forget to add the nozzle pressure and elevation pressure to the friction loss. Ex.: 1,000 gpm fog at 80 ft. ( 35 psi elev. + 100 psi fog nozzle + 50 psi friction loss = 185 psi E.P. )

    The real problem with the reply is caused by the many piping arrangements that are possible on an aerial. Also when not fully extended, the waterway size is equal to the I.D. of the smallest pipe in the waterway, so it would be difficult to calculate using the Hazen - Williams formula.

    Comment


    • #3
      Huh.....

      Supplying the waterway of a quint would be no different then the waterway of a straight ladder. You're going to have friction loss somewhere whether it be in the Engines discharge plumbing or that of the quint, either way you need to determine what that is. A pitot would be the most accurate. If you don't have a pitot, install a 2" tip like mentioned and read the gauge on the monitor, hopefully you have one. Gradually increase discharge pressure until you read 110 psi which is 1245 gpm. You can perform this at different extensions and elevation or even different tip sizes to get the results your after.

      Make sense?

      Comment


      • #4
        A few comments and maybe a question. First, the small gauge on monitor's seem to be notoriously inaccurate. We have seen up to 30 psi difference between a pitot and the little gauge. Better yet maybe putting in an inline 2.5" gauge between the gun and the stream shaper?

        We just ran an aerial hydraulics drill where we determined we could just about trust no guages beyond the engines discharge gauge. The aerial inlet gauge, the gun gauge and the flowminder were so far off the expected we could only look at elevation changes in the gauges. Next time we'll use the inline gauge and a pitot to verify.

        My question for Kuhshise: Does the general elevation formula assume a 90 degree elevation to the height?

        Comment


        • #5
          Reason for gauge errors in waterways

          RFDACM02:

          Yes, vertical change in height from the discharge gauge on the pump panel to the center of the nozzle. Elevation pressure doesn't care how far the water has to go, but is only affected by the vertical height in feet times 0.435 psi. per ft.

          Energy in the system can be either potential (pressure) or kenetic (velocity). One of the reasons that a gauge tapped into the waterway at the base of the nozzle is inaccurate is because it can't measure the energy of the speed of the water before it enters the shaper. It can only measure the pressure that is accelerating the water from the speed in the pipe to the speed at the exit of the nozzle. A 4" waterway at 1,000 gpm has a water speed of 24.16 ft / sec while the exit of a 2" tip needs a velocity of 96.6 ft / sec to flow that amount of water. Thus the nozzle acceleration is only 72.8 ft / sec.

          When you place a pitot gauge in the flowing stream, the water at the opening facing the flow is stopped (zero velocity) thus the kenetic energy is changed to potential energy (pressure) so we can know the gpm flowing through the nozzle. A properly installed gauge on a monitor should have the opening facing into the flow at the base of the nozzle and will read the true energy in the nozzle since part of it is kenetic and the remaining potential (pressure) will add to that giving the true pressure in psi causing the flow from the nozzle.

          Hope this isn't confusing.
          Last edited by KuhShise; 11-04-2008, 08:37 PM.

          Comment


          • #6
            Wrong.

            So if what you are saying is true, which it isn't, no discharge gauges are properly installed because no gauge reads directly into the stream. Why, because it doesn't have to. The force is exerted the same on all sides. A gauge located at the tip is reading the pressure within the plumbing at that point, that being your nozzle pressure.

            RFDACM02,

            I would say your calculations would be off because of restrictions at different points throughout the plumbing. With your pitot installed and knowing the flow, I would calibrate the flowmeter to that flow.

            Comment


            • #7
              Aerial Flow Chart

              To me, the easiest way to develop a flow chart is have the aerial horizontal at full extension at 0 degrees of elevation. Install a pitot test tip with a 2-1/4" bore nozzle. Keeps the pressures down a little from a 2" tip.
              So when you flow the waterway in this configuration you are measuring almost all friction loss in the waterway from the pump to the tip of the aerial. (yes you are getting a little bit of elevation loss from the difference in height from the pump to the turntable. Around 4' so less than 2 psi. small enough to ignore for test purposes.)
              Pump the waterway till you get 70 psi at the pitot gage (1260 gpm.)
              Record the pump panel pressure and the rear inlet gage pressure. (You may want to supply from another water source one day.) Calibrate the flow meter.
              So now you have the friction loss for the waterway system (Pump pressure - 70 psi pitot pressure.
              So now you can add .438 psi to the pump pressure for every 1' increase in tip elevation. Pump pressure + (.438 psi x 105') = Pump pressure + 46 psi at 105' of nozzle elevation.
              This will get you accurate with a straight bore tip. Since most new automatic nozzles hold an 80 psi back pressure you need to add 10 more psi to your pump pressure at each elevation with an automatic nozzle.

              Pump pressure + 56 psi at 105' nozzle elevation.
              Attached Files

              Comment


              • #8
                Originally posted by VanIsleEVT View Post
                RFDACM02,

                I would say your calculations would be off because of restrictions at different points throughout the plumbing. With your pitot installed and knowing the flow, I would calibrate the flowmeter to that flow.
                This is what we intended to do next.

                We did try the use of inline gauges on SB handlines behind the nozzle and found that they wouldn't register any pressure, but at the truck (between the discharge and the hose) they were on par with the panel gauges. Kuhshise's explanation seems to point to this issue.

                In checking for inaccuracies betwen gauges it would seem that if we stopped the flow at the tip and read each gauge in the system they should all be the same. Maybe this would slue us in to how far off any gauge might be? Probably not accurate to say "always add 10 psi to gauge "A" " ?

                Thanks for the info and education, though I don't want to stir a hornets nest.

                Comment


                • #9
                  Wrong.

                  So if what you are saying is true, which it isn't, no discharge gauges are properly installed because no gauge reads directly into the stream. Why, because it doesn't have to. The force is exerted the same on all sides. A gauge located at the tip is reading the pressure within the plumbing at that point, that being your nozzle pressure.
                  No, he his right. You have to understand total, dynamic or velocity, and static pressure to follow it. What you described is only static pressure and it is true that typical discharge guages are only reading static pressure, not total pressure. Typical static pressure gauges ignore velocity pressure and that is pretty typical for say water moving in pipes where the dynamic or velocity pressure is not a significant component of the total pressure. A pitot in the water stream measures total or what is called stagnation pressure as KS discussed.

                  Comment


                  • #10
                    We have placed an inline gauge on the master stream device between the shaper and the nozzle (we pulled off the stack tips and put a gauge in the middle, then put the stacks back on). Basically as close as we could get to the nozzle tip without using a pitot. When we did this we got the same results as when we used a pitot. I agree that you can't use an inline gauge before the stream shaper because you are then not taking into account the FL from the shaper. However I've seen the same result using a pitot and an inline gauge that was at the nozzle. Going on the premise that doing this will not give a 100% accurate reading because of the science discussed in previous posts, how inaccurate is this going to be? Is it a margin of error that we can measure on our gauges? I believe that as long as you don't have anything between the gauge and the nozzle such as a shaper or pipe bends you will get a usable reading that is accurate to the levels of our gauges.
                    I may speak gibberish, but I don't talk s***! -- Dropkick Murphys

                    Comment


                    • #11
                      FOKKER416:
                      Errors in reading would be approximately as follows: 4" waterway gauge will read 4.9 psi low; 3" waterway 15.4 psi low; dual 2 1/2" waterways 8 psi low; single 2 1/2" waterway 32 psi low. Just think about an eductor for foam. Making the velocity increase through a throat can cause the pressure in the venturi to go below atmospheric. This is just the pressure side of the curve leading up to that condition. Keeping the inlet to the gauge away from the sides of the stream will avoid the turbulent portion of the waterway and thus improve the consistency of the readings. These would be for a 2" tip at 1063 gpm.

                      Comment


                      • #12
                        fokker,

                        You are correct, you will get a number that is close enough. I too have done similar tests with the same results, pitot and inline gauge readings almost identical. That's all I did to determine the loss in the plumbing and waterway of our platform.

                        Comment

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