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FT900003
Rev A1
INTRODUCTION
Step Three
Technology:
The thermal dispersion flow switches measure liquid or gas temperature to determine changes
in flow velocity. As fluid flows across the sensing tips, the temperature is reduced proportionately as a
function of the flow rate. When a temperature or velocity shift reaches the user defined set point, the switch
changes state indicating the appropriate flow condition (flow of no‐flow).
FLOWLINE’s sophisticated electronics convert the temperature shift into a signal which indicates whether a
flow or no‐flow condition occurs. Depending on how the sensor is wired, this signal may be wired for normally
open or normally closed circuits.
FLOWLINE’s Thermo‐Flo™ flow switches have no moving parts to clog or foul, making them suitable for a
verity of applications, including non‐coating and non‐scaling liquids. The FT10 series directly measure mass
flow and can operate over board range of liquids from 0.4 to 1.2 specific gravity and 1 to 300 cp.
Initializing Sequence for FT10 series:
When the flow switch is powered up while submersed, the FT10 will
immediately indicate flow before switching to its correct state. A time delay may be used to eliminate the
initialization sequence. Flowline’s thermal dispersion relay controllers feature a 0 to 60 second time delay for
your convenience.
Set Points:
The FT10 liquid flow switch set point is factory calibrated to 0.2 fps and the GT10 gas flow switch
are set to 10 fps. To convert feet/sec to GPM, please refer to the chart below.
FT10
Flow Rate vs. Velocity
(gpm vs. fps)
GT10
Flow Rate vs. Velocity
(cfm vs. fps)
