Fluid Components International FS10A - Manual (Page 19)

FS10 Series
Fluid Components International LLC 17
Flow Switch Operation
Units supplied without factory trip point setting should be scaled in situ before setting the trip point. Default Universal Setting A from Bank
1 is recommended for most low flow sampling gas or liquid service. Gas and liquid service applications where higher flow rate detection is
required may select Universal Setting B from Bank 3.
Scaling is performed in the following order:
Minimum Flow Setting (Function 6)
Select function 6 to capture the minimum flow rate. In liquids, optimum performance is achieved by setting the Minimum Flow to a full line at
no flow. If possible, with liquids, slightly pressurize the pipe and block the flow using valves to assure a full and static condition. Capturing the
no-flow value in Function 6 establishes the zero point.
Maximum Flow Setting (Function 7)
Run the process at maximum flow and use this function to capture the maximum flow in gas or liquid. Since liquids transfer heat very ef-
ficiently, depending on the sensor assembly and fluid, maximum signal level will likely be achieved at flow rates under 2 feet per second,
though the actual flow in the tube may be higher. Capturing the maximum flow effectively establishes the span in the installation.
Note: Be sure to pause at least 30 seconds before capturing zero and span to assure unit has reached equilibrium.
Static/Dynamic Mode Option (Function 5)
This option provides dynamic ranging (span setting) of the unit for purposes of calibration. It is intended to aid the user in ranging the FS10 in
cases where the maximum flow is fluctuating and difficult to capture or requires action away from the FS10 installation.
Select button Function 5 to change between static and dynamic mode for setting the maximum span value
[CUST_FLOW_MAX]. The “static” default setting is used to capture the maximum flow in Function 7. If function 5 is changed to “dynamic”
setting, the FS10 will constantly update the maximum span value to reflect the maximum flow. The span setting increases (re-scales) to match
an increasing process flow and remains at the highest level achieved as long as the unit remains powered.
Important Note: When Function 5 is changed to Dynamic Mode, the span immediately drops to the value of the trip-point setting
and climbs from that point with flow. Therefore, a trip point should be captured (Function 2) at a flow lower than
the anticipated max span flow before placing unit in Dynamic Mode. Once the user is satisfied the maximum flow
is captured in Dynamic Mode, the unit should be switched back to Static Mode. The established span will remain.
CAUTION: A loss of power while in Dynamic Mode results in resetting the CUST_FLOW_MAX to the original trip
point value. Dynamic mode is not recommended if the application may see spiking flows or wet conditions in gas
applications that could result in a temporary and false indication of what the maximum flow should be.
Trip Point Adjust (Function 1 or 2)
There are two ways to set the trip point using the buttons.
Function 1 uses the LEDs as indicators to set the trip point in 10% increments within the established span.
Function 2 may be used to set the precise trip point by “capturing” the exact process flow rate. In liquids, make certain the desired trip
point is within the set operating range. That is, when capturing at the trip-point, the LEDs should be showing no greater than 90% flow.
NOTE: The trip-point setting is saved in feet/sec, therefore, changing the span later may alter the relative position of the flashing LED
indicating the trip-point value.
Low flow alarm applications with relay energized above the trip point (default setting): the trip point LED will flash quickly when the flow is
below the trip point. The LED flashes at a slower rate when the flow is at or above the trip-point.
Additional Switch Settings
Failsafe Position (Function 3)
This function establishes the state of the relay during normal operation and alarm condition. It is common to set the failsafe so that the relay
is “energized” or activated under normal operating conditions. An alarm condition (trip point activated) results in the de-energized state. That
assures an alarm state if power is lost to the device as well.
If the relay is bypassed and the device is used with the solid-state binary output, the system should be set up so a no-power condition results
in an alarm state. The transistor should be “on” under normal operating conditions, resulting in an approximate 5 Vdc signal to ground. Power
loss or alarm condition, results in 0 Vdc to ground.
Hysteresis (Function 8 and 9)
In the case of the flow switch, hysteresis is defined as the difference in signal level between turning on the relay and turning it off. If the
hysteresis is set to zero, that point is the same and can result in chattering, rapidly turning the relay on and off, in slow moving processes. A
hysteresis level is applied to minimize the possibility of chattering around the trip point. It is set as a percent of the trip-point value.