Flow meter selection

A.m blent Environment. The environment around the flow conduit must be considered in meter selection. Such factors as the ambient temperature and humidity, the pipe shock and vibration levels, the avadabiHty of electric power, and the corrosive and explosive characteristics of the environment may all influence flow meter selection. Special factors such as possible accidental flooding, the need for hosedown or steam cleaning, and the possibiHty of lightning or power transients may also need to be evaluated. 

Gas demand influences mass flow meter selection, as indicated in the following calculations ... 

The pediatric nurse is caring for a 7-year-old child with chronic reactive airway disease who is being discharged. The nurse must evaluate the breathing capacity of the child to determine the effectiveness of the medication regimen. Which interventions should the nurse implement when using the peak flow meter Select all that apply. 

Reynolds dumber. One important fluid consideration in meter selection is whether the flow is laminar or turbulent in nature. This can be deterrnined by calculating the pipe Reynolds number, Ke, a dimensionless number which represents the ratio of inertial to viscous forces within the flow. Because... 

Most flow meters are designed and caHbrated for use on turbulent flow, by far the more common fluid condition. Measurements of laminar flow rates may be seriously in error unless the meter selected is insensitive to velocity profile or is specifically caHbrated for the condition of use. 

Electromagnetic flow meters ate avadable with various liner and electrode materials. Liner and electrode selection is governed by the corrosion characteristics of the Hquid. Eor corrosive chemicals, fluoropolymer or ceramic liners and noble metal electrodes are commonly used polyurethane or mbber and stainless steel electrodes are often used for abrasive slurries. Some fluids tend to form an insulating coating on the electrodes introducing errors or loss of signal. To overcome this problem, specially shaped electrodes are avadable that extend into the flow stream and tend to self-clean. In another approach, the electrodes are periodically vibrated at ultrasonic frequencies. 

You have been asked by your boss to select a flow meter to measure the flow rate of gasoline (SG = 0.85) at 70°F in a 3 in. sch 40 pipeline. The maximum expected flow rate is 200 gpm, and you have a DP cell (which measures differential pressure) with a range of 0-10 in.HzO available. 

Fuel flow rate. Your instructor will show you how to vary the fuel flow rate to the burner head and also how to read the flow rate on the flow meter. Measure absorbance values at ten different flow rates, selecting a flow rate range that will maintain a flame while bracketing what the manufacturer s literature or your instructor may suggest as the optimum. 

There is need for greater care in motor alignment, and attention to this problem will reduce even further the frequency of bearing failures. Additional attention could be given to flow meters, and while most appear satisfactory, both in terms of durability and accuracy, some are most difficult to service. Knowing the alien-to-many materials ambient in the vicinity of seawater RO plants, I wonder why manufacturers do not pay more attention to materials selection here. 

Just as the electrical engineer selects resistors, capacitors, and transistors when designing an electric circuit, the chemical engineer selects valves, piunps, and flow meters to produce a flow system. The procedure followed in the design of a flow system is to determine ... 

The type of meter used for water flow depends on the flow rate and velocity. Meter types include Venturi, propeller, turbine, and magnetic. The manufacturer of each should be consulted for their limitations, which include pipe size, up- and downstream straight pipe available at flow meter installation, minimum and maximum velocity through meter, and calibration requirements. Unfortunately, meters are usually selected by pipe size, not flow rate, so the water meter is often grossly oversized for the flow rate through it. Because most meters are least accurate at the low velocity end of their measurement range, the result is that water flow is not accurately measured. 

Standard cubic meters per minute (SCMM) in selecting a mass flow meter. 

Figure 20 depicts the reaction data obtained from a proprietary reaction run in this fixed bed unit over a period of 7-8 hours. These graphs show the various gas and liquid flow rates, gas pressures at both the reactor inlet and the exit flow meter as well as the temperatures of the three reactor stages and the liquid level in the gas-liquid separator (GLS). The product composition is also measured by analyzing the samples taken by the automated sample collector. In this reaction, selectivity was a problem because of the formation of two byproducts. 

The required modules for both the TS-PFR and the TS-CSTR are identical in function if not in configuration. The major differences are introduced if the TS-CSTR is to be operated in the joystick mode, as described in Chapter 5. In that case the control of feed flows must be done using a device offering instant response to command inputs. This is generally not possible with standard flow-meters and additional thought must be given to the selection of flow-control devices. 

APCFs compression, storage, and dispensing development work began in October 2001. To date, APCI has completed the preliminary engineering work to determine the optimum configuration and selection of components for the H2 dispenser. Also, laboratory equipment to test H2 flow meters for use in the dispenser has been purchased and is being installed. 

Some considerations to keep in mind in selecting flow meters are ... 

Nicholson proposed a differential potentiometric tltrator involving two indicator electrodes for the automatic control of processes in industrial plants [35]. As can be seen from Fig. 7.20, the sample and reagent streams are split and led to two half-cells via capillary tubes adjusted to provide slightly different titrated fractions. The potential difference (AE) between the two indicator electrodes Is transmitted to a control and detection system (D) which regulates the flow of titrant in an automatic fashion by means of valve V, thereby maintaining the preselected AE between the two ends of the cell. The speed of titrant addition, reflected by the flow meter (M), is a measure of the sample composition. An evaluation of the instrument carried out by the titration of dichromate with iron(II) revealed that the conditions to be used must be carefully selected. Thus, stable electrode responses are only obtained in the zone where Fe(II) prevails, and not in that where dichromate prevails over the former as the process determining the potential obtained in such a zone is irreversible. This method therefore has limited application in the control of slow reactions. 

P pressure gauges RC,RA RCE reactor catholyte, anolyte compartments HA, HC anoljrte, cathol3de heat exchangers FM flow meter S gas/liquid separator C hydrocyclone AM,CM anolyte, catholjde tank ISE ion selective electrode ADDS chemical additions CW cooling water G gas vent D to drain F solid/liquid separator and collection tray PA,PC anolyte, catholyte pumps. 

The supply rates of the liquid were eontrolled in the range from 0.05 to 1 g/h by a so-called p-Flow mass-flow meter (Bronkhorst, High-Teeh B.V.). At room temperature, the liquid was drawn from a pressurised container with an inert gas blanket and measured by the liquid mass-flow meter. The required flow rate was controlled to the set-point value by a control valve (C), forming an integral part of the liquid flow and earner gas mixing valve (M). The formed mixture was subsequently led into the evaporator to achieve total evaporation (E). This explains the abbreviation of CEM , shown in Fig. 1, viz. Controller-Evaporation-Mixing, the three basic functions of the liquid delivery system. The main features of this liquid delivery system are a) accurately controlled gas/liquid mixture, b) fast response, c) high reproducibility, d) very stable vapour flow, and e) flexible selection of gas/liquid ratio. 

In contrast to other studies, oxidation carried out in this department on a Pt/7-Al203 catalyst has not uncovered any oscillatory behaviour in the temperature range of 100-185 °C. Addition of a hydrocarbon like but-l-ene, but-2-ene, or propene induces sinusoidal or relaxation type oscillations at temperatures above 150 °C. The experimental set-up used consists of a continuous recycle reactor system. The catalyst is packed in the cylindrical tubes. The gas flow rates are precisely measured with a bubble flow-meter. The reactor outlet is connected to a magnetic deflection mass spectrometer. An electronic peak select unit allows up to four mass numbers to be continuously monitored. The output data are connected to a PDP 11/45 computer for automatic and fast data logging. The data thus stored in the computer can be analysed later. The line diagram of the experimental set up is given in Figure 1. 

Selecting a flow meter for a given application depends on several criteria including ... 

Crabtree (2009) detailed most of the flow meters used in industrial plants. His classification for selecting measuring technology with respect to process application is reproduced in Table 6.3. All flow meters are suitable for clean liquids except for the Ultrasonic-Doppler instrument and only electromagnetic instruments are unsuitable for low conductivity fluids. Most instruments are suitable for high temperature operation or application under certain conditions except for the ultrasonic instruments. Many flow meters are suitable for gases. Few instruments can be used for open channel flow or pipes that are semifllled with the exception of weirs and flumes. 

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