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FC-21 Flow Computer
Flow Signal Timeout
The Flow Signal Timeout allows the user to enter a timeout of 0 to 99 seconds. If a batch is “Filling” and
zero flow persists for more than the user entered time then the batch will be aborted. This prevents over
flows due to faulty flow sensors and/or wiring.
Flow Equation
A flow control expression or algorithm describing a mathematical equation to be solved by a flow
computer in the desired application.
Follow, Alarm
Alarm relays which are non latching and whose output state is based solely on the comparison of the
current process value and the alarm setpoint (trip point).
Function Key
A key on a push-button panel or keyboard (whose function is described by the key label) used to
perform an instrument function or special routine.
Handshake
A means of controlling the information flow between two pieces of equipment to prevent the sending
device from transmitting information at a rate faster than what can be accepted by the receiver.
Hysteresis
The relay hysteresis is a "dead band" setting which allows the relay to remain energized for a given
amount below the setpoint. This is used to prevent relay chatter when the process value is near the
setpoint value.
Example: If the Preset is set at 100, and the hysteresis is set at 10, the relay will energize when the rate,
temp or dens. reaches 100, the relay will remain energized until the reading falls below 90.
Input Termination
Input signal lines on digital inputs often require pullup or pulldown resistor configurations to operate
properly with different sensor configurations. The FC-21 contains such resistors and may be enabled via
the setup menu.
Inhibit Totalizer
"Inhibit Total" is a Control Input 1 setting that is used to stop the totalization. If enabled, a voltage level
on control input 1 will inhibit the total as long as the voltage is present. This feature is useful during
meter proving and in applications that provide a sensor to signal the flow computer when fluid is
present.
K-Factor
A scaling factor derived from the pulses produced by a flowmeter output, expressed in pulses per unit
(i.e. pulses/gallon)
LCD
Abbreviation for: Liquid Crystal Display
Limit Setpoint
An alarm trip point setting which specifies the value or magnitude of a process parameter necessary to
activate an alarm indicator or control relay.
Linear Flowmeter
A flow measurement device whose output is proportional to flow.
Linearization
The mathematical correction of a nonlinear device. The FC-21 uses a linearization Table which is made
up of input/output values and makes interpolations of the table to arrive at a "linearized" measurement.
LinTbl
Abbreviation for Linearization Table.
Low Flow Cutoff
A value set at which any flow measurements read below this value will be ignored.
Low Pass Filter
A low pass filter passes low input frequencies while blocking high frequencies. In the FC-21, this is the
maximum input count speed to be encountered in an application. It is expressed in counts per second
(Hz).
Mass Flow
12. Glossary Of Terms (Continued)