8: Pump and Pipeline Hydraulics
- Page ID
- 44304
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 8.1: Introduction
- We’ve all had the experience of carrying a bucket of water up a hill. It takes work to get it done, right? In a similar fashion it takes energy to move and distribute water for irrigation. Proper development and operation of irrigation requires that considerable attention be given to the hydraulics of the system.
- 8.2: Basic Hydraulics
- There are two important physical laws that apply to hydraulics, conservation of energy and conservation of mass (continuity). The energy in the water will be in any of the following forms: kinetic energy due to the velocity of the water, potential energy due to the elevation of the water relative to an arbitrary reference elevation, and potential energy due to water pressure.
- 8.3: Pressure Loss
- An example is the difficulty in pouring syrup as compared to water. Similarly, the rougher the inside of the pipe or conducting vessel, the higher the friction loss. In irrigation, the interest is in determining the friction loss in pipelines so that the proper pipe diameter is selected and the energy requirement for developing the pressure needed within the system can be calculated.
- 8.4: Pipelines
- Irrigation pipelines are made of many materials. Currently, the most common materials used for aboveground sprinkler systems and gated pipe systems are aluminum and ultraviolet radiation protected PVC (polyvinyl chloride plastic). Center pivot and lateral systems are the exception where it is common to use galvanized steel as the pipeline material. Above ground microirrigation laterals are usually made of polyethylene (PE) plastic....
- 8.5: Pumps
- Irrigation systems are designed to operate at specified pressures and flow rates. In order to develop the required pressure and to lift water from a reservoir or a well, it is often necessary to pump the water. Pumps that lift and pressurize water in irrigation most commonly use the principal of centrifugal force to convert mechanical energy into hydraulic energy.
- 8.6: Power Requirements
- A pump transfers energy from an electric motor or engine to the water (Figure 8.15). Since a pump cannot be 100% efficient, pump efficiency (Ep) is used to account for the energy lost in pumping and is defined as: It is also necessary to determine how large of an engine or motor is required to pump the water. Horsepower (hp) is the typical unit of power in the USCS system and is defined as:
- 8.7: Energy Consumption
- Pumping water for irrigation consumes energy; it takes energy to lift water and it takes energy to pressurize water. Below we discuss ways to determine energy consumption so that irrigation managers can appreciate the energy costs of operating irrigation systems. To analyze the rate of energy consumption, we will use what is called the Nebraska Pumping Plant Performance Criteria (Kranz et al., 2012a; Martin et al., 2017). given in Table 8.6. To illustrate how this table was developed, consider a
- 8.8: Summary
- Transporting water for irrigation in pipelines requires energy. Water moving in pipelines obeys the basic laws of physics, conservation of energy and conservation of mass. The components of energy in the water are made up of kinetic, pressure, and elevation energy. While water is moving, the forms of energy can exchange with one another and some energy will be lost due to friction in pipelines and minor losses....
- 8.9: Questions
- Explain the three energy forms in irrigation system hydraulics. List three things that will increase pressure loss due to friction and explain why they impact this loss of energy. A furrow irrigated field uses 10-in gated pipe and the well flow rate is 1000 gpm. The last irrigation set in the field starts 900 ft from the well and there is a 9-ft elevation rise or gain from the well to the last set.
- 8.10: References
- Colt Industries. (1979). Hydraulic handbook (11th ed.). Kansas City, KS: Colt Industries, Fairbanks Morse Pump Division. Dorn, T. W., Fischbach, P. E., Eisenhauer, D. E., & Gilley, J. R. (1981). It pays to test your irrigation pumping plant. EC 81-713. University of Nebraska Ext. Kranz, W. L., Martin, D. L