Flow measurement throat diameter

Based on the measured pressure difference over the device, the throat diameter, and some other parameters, the flow rate can be determined. The equation for the volume fkw rate is, in general, ... 

You want to use a venturi meter to measure the flow rate of water, up to 1000 gpm, through an 8 in. sch 40 pipeline. To measure the pressure drop in the venturi, you have a DP cell with a maximum range of 15in.H20 pressure difference. What size venturi (i.e., throat diameter) should you specify ... 

The manometer deflection of a venturi meter in terms of equivalent water is 205 mm. If the throat diameter is 112.1 mm and the venturi is used to measure flow in a 250-mm pipe, calculate the rate of discharge. 

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 ... 

A horizontal venturi meter having a throat diameter of 20 mm is set in a 75-mm-ID pipeline. Water at 15°C is flowing through the line. A manometer containing mercury under water measures the pressure differential over the instrument. When the manometer reading is 500 mm, what is the flow rate in gallons per minute If 12 percent of the differential is permanently lost, what is the power consumption of the meter ... 

The hydraulic rock type classification provides a physical measure of a rock s flow and storage properties at current conditions. When described on the basis of the dominant pore throat diameter determined from high-pressure mercury capillary pressure data, distinct groupings of rocks having similar flow and storage properties, i.e. hydraulic rock types, are... 

Metering Flow by a Venturi. A venturi meter having a throat diameter of 38.9 mm is installed in a line having an inside diameter of 102.3 mm. It meters water having a density of 999 kg/m. The measured pressure drop across the... 

The pore size distributions obtained by the mercury intrusion and liquid extrusion techniques are expected to be different. Mercury intrusion allows access to the pores from both sides of the mat and the entire pore volume is likely to be sampled. For pores that have large surface openings, the liquid extrusion generally tends to imderestimate the pore volumes relative to those measured by intrusion porosimetry. Liquid extrusion measurements yield the pressure needed to push the liquid past the most constricted part (or the throat ) of the pore. The pore volume of the channel is estimated based on the throat diameter. This also introduces directionality to the liquid extrusion measurement For a sample where porosity includes converging or diverging channels, the pore volumes (and pore dimensions) obtained from the liquid extrusion method will depend on the direction of the gas flow into the membrane. However, this is not expected to be a serious source of error in routinely characterizing nanofiber mats. 

Saturated liquid hydrogen at 0.101 MPa is flowing through a 3.8-cm i.d. tube. A Venturi meter with a 1.9-cm throat diameter is used to measure the flow rate. For a measured pressure drop of 1.07 kPa, find the volumetric flow rate and the mass flow rate. 

Liquid hydrogen at 22 K flows through a pipe having an inside diameter of 40 mm. A Venturi meter having a throat diameter of 20 mm is placed in the line to measure the flow rate of the fluid. Determine the volumetric flow rate and mass flow rate of the liquid hydrogen if the pressure difference for the meter is 1.75 kPa. 

Flow Nozzles. A flow nozzle is a constriction having an eUiptical or nearly eUiptical inlet section that blends into a cylindrical throat section as shown in Figure 8. Nozzle pressure differential is normally measured between taps located 1 pipe diameter upstream and 0.5 pipe diameters downstream of the nozzle inlet face. A nozzle has the approximate discharge coefficient of an equivalent venturi and the pressure drop of an equivalent orifice plate although venturi nozzles, which add a diffuser cone to proprietary nozzle shapes, are available to provide better pressure recovery. 

The rate of flow of water in a 150 mm diameter pipe is measured with a venturi meter with a 50 mm diameter throat. When the pressure drop over the converging section is 121 mm of water, the flowrate is 2.91 kg/s. What is the coefficient for the converging cone of the meter at this flowrate ... 

A venturi meter with a 50 mm throat is used to measure a flow of slightly salty water in a pipe of inside diameter 100 mm. The meter is checked by adding 20 cm3/s of normal sodium chloride solution above the meter and analysing a sample of water downstream from the meter. Before addition of the salt, 1000 cm- of water requires 10 cm3 of 0.1 M silver nitrate solution in a titration. 1000 cm3 of the downstream sample required 23.5 cm3 of 0.1 M silver nitrate. If a mercury-under-water manometer connected to the meter gives a reading of 20S mm, what is the discharge coefficient of the meter Assume that the density of the liquid is not appreciably affected by the salt. 

The value of the coefficient of discharge Cd for orifice meters depends on the properties of the flow system, the ratio of the orifice diameter to the upstream diameter, and the location of the pressure-measuring taps. Values of Cd for sharp-edged orifice meters are presented in Fig. 14-55. These values apply strictly for pipe orifices with throat taps, in which the downstream pressure tap is located one-third of one pipe diameter from the downstream side of the orifice plate and the upstream tap is located one pipe diameter from the upstream side. However, within an error of about 5 percent, the values of Cd indicated in Fig. 14-55 may be used for manometer taps located anywhere between the orifice plate and the hypothetical throat taps. 

It was necessary in the tests for several nozzles of the same size to be arranged in parallel so as to make the reaction magnitudes large enough for precise measurement. Each group contained between 6 and 14 nozzles, and was supplied with steam by an inlet pipe of large diameter. Since the mass flow through the pipe and the nozzle throats must have been the same, we may write the continuity equation ... 

A series of experiments has been carried out in the group of G. Brenn, TU Graz, Austria, for water sprays and PVP/water (20% PVP and 80% water by mass) sprays in air with different liquid mass inflow rates [42]. Various atomizers with different dimensions of swirl chambers and exit diameters were used. At various cross-sections, the droplet sizes and velocities are recorded for different liquid inflow rates using phase Doppler anemometry (PDA) [52]. The present simulations concern the experimental data using the Delavan nozzle SDX-SD-90 with an internal diameter of 0.002 m and an outer diameter of 0.012 m at the nozzle throat and 0.016 m at the top [42]. The liquid inflow rates for water/air spray are 80kg/h and 120 kg/h, and a 112 kg/h flow rate is used for the spray of a PVP/water solution in air. The spray is injected into a cylindrical spray chamber with a diameter of 1 m. The carrier gas is at standard conditions. Measurements are taken at cross-sections of 0.08 m, 0.12 m, and 0.16 m away from nozzle exit. The experimental data at the closest position to the nozzle is used to generate initial data for the numerical computations [53]. 

Temperature Correction. A temperature correction factor, must be used to account for any change of the area of section A 2 of the primary element when the operating temperature differs appreciably from the ambient temperature at which the device was manufactured and measured. If the meter is to be used under temperature conditions within the range of ordinary atmospheric temperatures, any difference between the thermal expansion of the pipe and the primary element may be ignored and the diameter ratio, p, may be considered to be unaffected by temperature. At cryogenic temperatures, the material for the throat liner of a Venturi tube, a flow nozzle, or an orifice plate should have a coefficient of thermal expansion as close as possible to that of the pipe. 

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