A mass flowmeter measures flow rate in weight per unit time rather than volume. This measurement is independent of temperature and pressure.
Input and Output Measurement Standards
Although an input and an output standard are needed, smart mass flowmeters are digital instruments, so they also require a special communication device. This device, called an interface device or communicator, is used for configuration and calibration.
The interface device must be connected to the mass flowmeter. It can be connected at any point in the loop as long as it is in parallel with the signal lines.
When the device is turned on, a self-diagnostic program is performed. After the self-test is complete, press the process variable key to display current readings from the transmitter.
Keys have the following functions:
HELP = gives an explanation of the current display and the function keys
RESTART = initiates communication with the smart transmitter
PREVIOUS FUNCTION = returns user to last decision level
ALPHANUMERIC KEYS = enter information into the interface
Configuring Mass Flowmeters
Configuration defines the parameters of the transmitter’s operation. To begin on-line configuration, press the “config” key on the interface device. Then enter information to identify the instrument.
The instrument parameters are checked and displayed by the interface device. Make any corrections to these displays by following the prompts on the interface device display. With the changes made, press the restart key to download the data to the transmitter. This completes the configuration. Now verify span and zero.
Correcting Errors
To establish the zero and span values, the flow tube must be full of process liquid with no flow. Because actual process fluid is used, this procedure is typically done on an installed transmitter.
Press the “format” key followed by the “proceed” key. Then press the “autozero” key.
The autozero automatically establishes zero to the properties of the process fluid.
The resulting display will indicate that the mass flowmeter is properly calibrated.