ASME MFC-6:2013 pdf free downlaod

ASME MFC-6:2013 pdf free downlaod.Measurement of Fluid Flow in Pipes Using Vortex Flowmeters.
5.1.2.2 Digital Transmitters. Digital transmitters use one or more microprocessors to process raw input signals and provide output signals and a user interface. These transmitters are often referred to as smart transmitters Their use of microprocessors provides several advantages over analog transmitters. Because the input signals are processed digitally, these transmitters can analyze the signals using mathematical algorithms to determine installation quality, external interference, and noise. Based on this analysis, the transmitters may be able to digitally filter out spurious signals. The use of microprocessors and digital processing minimizes the effect of component drift that may occur in analog transmitters. Digital transmitters may also be able to compensate for changes in the meter K factor caused by changes in process temperature and pressure.
Typical human interface is via a digital numeric or graphical display and buttons and optical or magnetic sensors to program parameters, or via a handheld communicator. Digital transmitters are programmable for range and other parameters in user-selectable units and languages. This configuration is stored on the transmitter and may also be uploaded via the communication protocol to other devices.
Digital transmitters may also include the ability to program a low-flow cutoff below which the instrument either emits an error signal or holds the output to zero. Alternatively, at no-flow conditions, the digital transmitter may determine the low-flow cutoff by differentiating between signal and noise, and adjust the measurement threshold accordingly.
Digital transmitters may be enabled with protocoLs that allow communication with other compatible instruments, communication devices, and control systems such as distributed control systems (DCS). Most digital transmitters include a programmable output range of 4 mA to 20 mA unless precluded by a communication protocol. They are also likely to include a programmable pulse or frequency output range.
5.1.2.3 Multivariable Transmitters. Multivariable transmitters are digital transmitters equipped with multiple inputs to the electronics to provide the temperature and pressure of the fluid that the meter is measuring. Multivariable transmitters perform a larger number of calculations than do typical digital transmitters.
The multi ariable transmitter provides the temperature and, if applicable, pressure measurements to the end user via either a digital communications protocol or multiple 4-mA to 20-mA outputs. In addition, since the multivariable transmitter computes the density of the fluid, it can provide this value as well as a number of other computed fluid parameters to the user. Core.ult the manufacturer’s literature to determine what variables the multivariable transmitter can calculate. The K factor is a nonlinear function of the Reynolds number (see Fig. 9.2-1), and the multivariable transmitter can compute the Reynolds number and correct the nonlinearity in the K factor. The flowing density of the fluid can be used to predict the expected strength of the vortices at a specific flow rate, allowing more accurate filtering algorithms in the transmitter to address signal interferences at low-flow rates.