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    Jessray Repunte
    The document describes an experiment to calibrate and use a venturi meter to measure fluid flow rates. It explains that a venturi meter works by measuring pressure differences upstream and downstream of a constricted throat section. The experiment involves calibrating the venturi meter to determine its discharge coefficient, then using it to measure water flow rates and comparing the measured rates to calculated theoretical rates. Key steps are to connect manometers to pressure taps, take readings at varying flow rates, and calculate flow rates using continuity equations and Bernoulli's theorem.

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    Untitled

    Uploaded by

    Jessray Repunte
    18 views7 pages
    The document describes an experiment to calibrate and use a venturi meter to measure fluid flow rates. It explains that a venturi meter works by measuring pressure differences upstream and downstream of a constricted throat section. The experiment involves calibrating the venturi meter to determine its discharge coefficient, then using it to measure water flow rates and comparing the measured rates to calculated theoretical rates. Key steps are to connect manometers to pressure taps, take readings at varying flow rates, and calculate flow rates using continuity equations and Bernoulli's theorem.

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    The document describes an experiment to calibrate and use a venturi meter to measure fluid flow rates. It explains that a venturi meter works by measuring pressure differences upstream and downstream of a constricted throat section. The experiment involves calibrating the venturi meter to determine its discharge coefficient, then using it to measure water flow rates and comparing the measured rates to calculated theoretical rates. Key steps are to connect manometers to pressure taps, take readings at varying flow rates, and calculate flow rates using continuity equations and Bernoulli's theorem.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    18 views7 pages

    Untitled

    Uploaded by

    Jessray Repunte
    The document describes an experiment to calibrate and use a venturi meter to measure fluid flow rates. It explains that a venturi meter works by measuring pressure differences upstream and downstream of a constricted throat section. The experiment involves calibrating the venturi meter to determine its discharge coefficient, then using it to measure water flow rates and comparing the measured rates to calculated theoretical rates. Key steps are to connect manometers to pressure taps, take readings at varying flow rates, and calculate flow rates using continuity equations and Bernoulli's theorem.

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    of 7

    DEPARTMENT OF MECHANICAL ENGINEERING

    ME LABORATORY 1

    EXPERIMENT NO. 8

    FLOW MEASUREMENT WITH VENTURI METER

    OBJECTIVES:

    1. To make a comparative study of simple metering devices employed in the


    measurements of flow of water, steam, air and other gases like venturi and/or orifice.
    2. To calibrate venturi and/or orifice meter by determining its discharge coefficient.
    3. To measure volumetric flow rate of liquid (water) and/or gases (air) using venturi
    and/or orifice meters.

    LEARNING OUTCOMES:
    At the end of the experiment the student will be able to:
    1. Demonstrate the procedure on how to calibrate venturi meter
    2. Measure flow of water or air using venturi meter.
    3. Differentiate the venturi meter from pitot tube in measuring volume flow rate.
     

    THEORY:

    To control any processes, it is desirable to know the amount of material entering and leaving
    the process. Because materials are transported in the form of fluids, it is important to
    measure the rate at which a fluid is flowing through a pipe or other channel. Many different
    types of meters are used namely:
    1. meters based on direct weighing or measurement of volume
    2. positive-displacement meters
    3. area meters
    4. current meters
    5. head-meters
    6. magnetic meters
    Most widely used for flow measurement are several types of area meter like rotameters of
    various design and head meters like venturi meter, orifice, nozzle, and pitot tube (see figures).
    Venturi meter is a flow measuring device which consists of a pipe/tube of circular cross-section
    which converges to a throat and then diverges to the original diameter of the pipeline. In this
    cylindrical pipe several small holes lead into a piezometer taps so that a connection may be for
    measuring the static pressure before it enters the venturi construction, at the mouth, and at
    the section of least cross-section, the throat.

    1
    Pitot tube

    Typical venturi meter has a convergent-divergent design, which forms the basis of most
    engineering standards, divergent section of about 21°-10° total angle connect the short
    straight section called throat. The end of the throat leads into the exit cone or diffuser, which
    has a total angle of about 5° to 7°. The venturi test apparatus use in this laboratory ( may
    vary depends on availability) test comprises a parallel bore section of 20 mm diameter 180
    mm long followed by the convergent section in which the diameter is reduced to 10 m, a
    throat of 10 mm diameter 10 mm long, a divergent section in which the diameter is
    increased to 20 mm and a parallel bore outlet section of 20 mm diameter as shown.

    Applying Bernoulli’s Theorem to inlet and throat of the tube, neglecting losses.
    2
    The quantity of fluid flow can be determined from the continuity equation.

    Q = A1 V1 = A2 V2

    Note:
    For Orifice Meter, the same equation applies.

    3
    Orifice Meter

    Thick Plate

    Thin Plate

    PROCEDURE:

    Calibration of Venturi / Orifice Apparatus on water:


    Set up the Venturi meter /Orifice meter apparatus. Start the pump and gradually open the
    main regulating flow valve to fix the water flow rate. Connect the tubes from the
    venture/orifice pressure tapping points to the manometer (mouth or inlet tap point and
    throat tap point), care must be taken to ensure that there is no trapped air in the connecting
    lines. Allow ample time to stabilize the flow before taking any readings. Read and record the
    difference of water elevation, H of the piezometer tapped at the mouth and throat of the
    venturi apparatus (upstream and downstream of the orifice meter). Record the diameter of
    4
    the cylindrical cross-section of the tapping points of the venture/ orifice apparatus. Compute
    the theoretical volumetric flow rate from the equations illustrated in the THEORY. For any
    reading of H, collect the volume discharge at the outlet and measure the time to collect
    certain quantity of water either in the steeped measuring tank or using a graduated cylinder.
    Record the volume collected and the time. Compute the actual volumetric flow rate from the
    volume collected divided by the time obtained previously. Take several trials by adjusting the
    main flow regulating valve. Record the coefficient of discharge of the Venturi/ Orifice
    apparatus and compute the average value (the typical value is about 0.97 for the venturi
    meter, and about 0.60 orifice meter).
    Volumetric flow rate determination by Venturi meter / Orifice meter:
    Set-up the Venturi/ Orifice apparatus as described in the procedure of part 1. Operate the
    Pipe-Friction Apparatus volumetric flow rate. Read and record the difference of water level
    of the piezometers tapped on the venture/ orifice apparatus. Compute the actual volumetric
    flow rate from equation in the “THEORY” using the average coefficient discharge obtain from
    Part 1. Determine the actual volumetric flow rate from the volume of water collected at the
    outlet divided by the time of collection. Compare the results and get the percentage error.
    Make several trials at the different volumetric flow rate.

    DETAILED PROCEDURE:

    Part 1: Calibration of Venturi/ Orifice meter

    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________

    Part 2: Volumetric flow measurement by Venturi/ Orifice meter

    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________

    TABULATED DATA AND RESULTS:

    Part 1: Calibration of Venturi / Orifice Apparatus:

    Volume Actual
    D1 D2 A1 A2 H time Cd Ave
    Trial R Collected Q
    mm mm m2 m2 mm sec Cd
    ml m3 /s
    1
    2
    3

    Part 2: Determination volumetric flow rate by Venturi / Ori fice meter

    Comp Q Volume Expt Q


    Ave A1 H time %
    3 Collected 3
    Cd m2 mm m /s sec m /s Error
    ml

    5
    QUESTIONS:

    1. How does a venturi meter measures flow?


    2. How does an Orifice work?

    6
    3. What is the difference and the similarity between orifice meter and
    venture meter?

    OBSERVATION & INTERPRETATION OF RESULTS

    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________

    CONCLUSION:

    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________
    ____________________________________________________________________________

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