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ASME MFC-22-2007 pdf download

ASME MFC-22-2007 pdf download.Measurement of Liquid by Turbine Flowmeters.
repeatability ofmeasurements (qualitative): the closeness of agreement among a series of results obtained with the same method on identical test material, under the same conditions (i.e., same operator, same apparatus, same laboratory, and short intervals of time). reproducibility: the closeness of agreement between results obtained when the conditions of measurement differ; for example, with respect to different test appara- tus, operators, facilities, time intervals, etc. Reynolds number: a dimensionless parameter expressing the ratio between inertia and viscous forces. turbine meter: a flow measuring device with a rotor that responds to the velocity of flowing fluid in closed con- duit. The flowing fluid causes the rotor to move with a tangential velocity that is directly linearly proportional to the volumetric flow rate. 3.2 Symbols See Table 1. 4 PRINCIPLE OF MEASUREMENT 4.1 Measuring Mechanism The measuring mechanism consists of the rotor, rotor shafting, bearings, and the necessary supporting struc- ture (Figs. 2 and 3). The flowing fluid passing through the blades of the rotor, which are at an angle to the direction of the flow, imparts a tangential force on the blades. This tangential force causes the rotation of the rotor that is directly linearly proportional to the axial 2 flow rate throughthe meter. For ideal fluids and friction- less rotor, the rate of rotation is linearly proportional to the axial flow velocity and the constant of proportional- ity is a function of the blade angle. 4.2 Output and Readout Device 4.2.1 The rate ofrevolution of the rotor is normally determinedfromtheblade passingfrequencyorbyother means that relates to the rate of rotation. 4.2.2 Turbine meter output may be mechanical, electrical, electromechanical, optical, analog, and digital. The readout devices may be of any form suitable for the application. 4.2.3 For electrical pulse output meters, the output includes the pulse detector system and all electrical con- nections necessary to transmit the indicated rotor revo- lutions outside the body for uncorrected volume registration. 5 SELECTION OF METER AND ACCESSORY EQUIPMENT FOR FLOW RATE DETERMINATION For proper selection and operation of the meter, the following information may be necessary: (a) fluid properties of the flowing stream including viscosity, vapor pressure, toxicity, corrosiveness, lubrica- tion properties, specific gravity, etc. (b) flow rate range and operational conditions includ- ing unidirectional or bidirectional flows and continuous or intermittent flows (c) performance characteristics that are required for the application including linearity over a specified flow range, repeatability at any flow rate, and improved lin- earity over a flow range (d) the flange rating, area classification,materials, and dimensions of the equipment used (e) available space for the meter installation and prov- ing facility, if required for the application (f) operating pressure ranges, acceptable pressure losses through the meter installation, and necessary con- sideration to avoid vaporization of the fluid while pass- ing through the meter (g) operating temperature range and the applicability of the automatic temperature compensation (h) effects of corrosive fluids and contaminants on the meter (i) amount and size of the suspended solids in the flowing stream including filtering equipment for the metering section (j) types of readout and printout devices, or desired output system to be used for signal preamplification and output units of the measurement as required (k) for multiple meter-run installations and how a meter is taken in or out of service during operation of the entire system
6 INSTALLATION Details for the installation of turbine meters are pro- vided in paras. 6.1 through 6.4. Figure 4 is a typical schematic diagram of a unidirectional turbine meter system. 6.1 Flow Conditioning The meter performance is affected by swirling and asymmetric flow profiles. Flow conditioning remediates these adverse conditions. Figure 5 is a typical installation of an upstream flow conditioner.

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