Examples venturi meter

Rate Meter Measures the instantaneous volume flow rate through the sampling systems. An example would be a rotameter or venturi meter. Used to set precise flow rate for flow sensitive sampling devices. 

See Derivation of head loss in a sudden expansion later in this section and the Venturi Meter in Section 3.7 for examples of the use of the Continuity Equation.]... 

See Venturi Meter in section 3.7 below for an example of the use of Bernoulli s Equation.]... 

Example 3.6 The flow to a water treatment plant is 0.031 cubic meters per second. The engineer has decided to meter this flow using a venturi meter. Design the meter if the approach pipe to the meter is 150 mm in diameter. 

Example 8.4. A venturi meter is to be installed in a 100-mm line to measure the flow of water. The maximum flow rate is expected to be 75 m /h at 15°C. The manometer used to measure the diflerentia pressure is to be filled with mercury, and water is to fill the leads above the surfaces of the mercury. The water temperature will be 15°C throughout, (a) If the maximum manometer reading is to be 1.25 m and the venturi coefficient is 0.98, what throat diameter, to the nearest millimeter, should be specified for the venturi ( ) What will be the power to operate the meter at full load if the pressure recovery is 90 percent of the differential pressure ... 

Example 5.7. The venturi meter in Fig. 5.8 has water flowing through it. The pressure difference P — P2 is X Ibf/in The diameter at point 1 is 1 ft, and that at point 2 is 0.5 ft. What is the volumetric flow rate through the meter ... 

Example 5.12. Water flows from a pressure vessel through a venturi meter to the atmosphere (see Fig. 5.15) Pj = 10psig and What is the... 

If the venturi meter in Example 5.7 is to be used on a day-to-day basis, then it will be useful to have a plot of flow rate versus pressure drop, so that we can read the pressure drop and simply look up the flow rate. Sketch such a plot for flow rates... 

Instruments which measure the rate of flow (velocity) of liquids and gases are called flowmeters they may be broadly defined as being mechanical or electronic in operation. Examples of mechanical flowmeters are orifice plate and float meters (Fig. 5.8), venturi meters, and pitot tube meters, all of which depend on a constriction being introduced into the flow stream in order to produce a difference in pressure across the constriction. The rate of flow can then be obtained from the difference in pressure. 

The proper installation of both orifice plates and Venturi-type flow tubes requires a length of straight pipe upstream and downstream of the sensor, ie, a meter mn. The pressure taps and connections for the differential pressure transmitter should be located so as to prevent the accumulation of vapor when measuring a Hquid and the accumulation of Hquid when measuring a vapor. For example, for a Hquid flow measurement in a horizontal pipe, the taps are located in the horizontal plane so that the differential pressure transmitter is either close-coupled or connected through downward sloping connections to allow any trapped vapor to escape. For a vapor measurement in a horizontal pipe, the taps should be located on the top of the pipe and have upward sloping connections to allow trapped Hquid to drain. 

The most difficult part of a field test is the flow meter, if it wasn t planned in the construction phase. There is no way to simulate a meter run if you don t have the proper pipe length. Figure 10-8 is an example of the requirements. An ASME long radius flow nozzle is preferred by the author, though a short throat venturi will do. The probability is that an orifice is all that will be available. It should be examined before and after the test to verify not only the bore diameter, but the finish. The bore should... 

In this chapter we will illustrate and analyze some of the more common methods for measuring flow rate in conduits, including the pitot tube, venturi, nozzle, and orifice meters. This is by no means intended to be a comprehensive or exhaustive treatment, however, as there are a great many other devices in use for measuring flow rate, such as turbine, vane, Coriolis, ultrasonic, and magnetic flow meters, just to name a few. The examples considered here demonstrate the application of the fundamental conservation principles to the analysis of several of the most common devices. We also consider control valves in this chapter, because they are frequently employed in conjunction with the measurement of flow rate to provide a means of controlling flow. 

Differential Pressure Meters Differential pressure meters or head meters measure the change in pressure across a special flow element. The differential pressure increases with increasing flow rate. The pitot tubes described previously work on this principle. Other examples include orifices [see also Eqs. (6-111) and (8-102), and Fig. 10-14], nozzles (Fig. 10-19), targets, venturis (see also Sec. 8 and Fig. 10-17), and elbow meters. Averaging pitot tubes produce a pressure differential that is based on multiple measuring points across the flow path. 

Flow rate is typically measured in gallons per minute (gpm) or gallons per hour (gph). A variety of devices can be used to accomplish flow measurement. Common examples of flow measurement devices are orifice plates, venturi nozzles, nutating disc meters, turbine flow meters, oval gear meters, rotameters, pitot tubes, weir and flume, and flow transmitters. Figure 7-4 shows a few examples of flow-measurement devices. 

Figure 8-2 shows an example of a flow control loop. Flow loops are typically designed so that a measurement of the flow rate is taken first and then the flow is interrupted or controlled downstream. Flow control loops start at the primary element. Flow control primary elements may include orifice plates, venturi tubes, flow nozzles, nutating disks, oval gears, or turbine meters. The most common primary element is the orifice plate, which artificially creates a high-pressure/low-pressure situation that can be measured by the transmitter. Primary elements are typically used in conjunction with a transmitter. 

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