Flow Rate Detection; Interface Detection - ABB TX series Operating Instructions Manual

6.0

FLOW RATE DETECTION

Configure circuit board jumpers JP3 (Relay State A) so the relay will be energized (green LED on) at the minimum flow
rate then adjust as follows:
Allow the product to flow at the minimum rate for approximately three minutes. (This will allow the unit to establish
an accurate flow set point and delta voltage.) The orientation of the probe is important to minimize the time to
respond to a minimum flow rate. If the probe head is turned after adjustment, the unit will not respond correctly.
Adjustment could be problematic due to the minimum torque required to the probe head and its orientation. The switch
should never be installed near a bend in the pipe.
Adjust potentiometer (R18 on drawing p.7) on circuit board until green LED changes state as follows, at flow or at
level:
•
If LED is on - turn potentiometer counterclockwise
•
If LED is off - turn potentiometer clockwise
Adjust the pot where the green LED is just on, this is the set-point. A flow rate greater than the minimum will keep the
LED on and the relay energized. A flow rate less than the minimum will turn off the LED and de-energized the relay. In
State B, the relay can be made to work so the LED is off above a flow rate. The hysteresis is about 10 mV. Moving JP3
to (Relay State B) reverses the function of the relay and the LED. When the LED is on the relay is energized.
There is an inherent time delay that can not be compensated in a flow rate, interface or temperature application. The
larger the difference in flow rates (minimum and maximum) the longer it will take the switch to respond. If a quicker
response time is needed, the TQ version may be the solution. For small flow rates, the IX or IM (in line unit) would be
the option. The delta voltage will decrease. With the dual switch point (top board) the delta voltage can be monitored
and/or plotted to determine flow rate (inverse relationship and non-linear). The voltage output can not be used with
temperature.
This switch can be configured to detect the interface between any two of the following mediums: granular solids (sand)
and liquid (oil), foam and liquids, hydrocarbons (oil) and aqueous solutions (water), or whenever there is a unique
seperation of product/s with reference to its thermal conductivity. The unit would likely be mounted horizontally (or
vertically with an extended probe) and the insertion level of the switch would be the level of the interface. The board
setting can be adjusted so the LED is ON or OFF (JP3/JP11 setting) when the interface is detected. Consult factory for
options and settings in this application.
7.0

INTERFACE DETECTION

This switch can be configured to detect the interface between any two of the following mediums: granular solids (sand)
and liquid (oil), foam and liquids, hydrocarbons (oil) and aqueous solutions (water), or whenever there is a unique
separation of products with reference to thermal conductivity. The unit would likely be mounted horizontally (or verti-
cally with an extended probe) and the insertion level of the switch would be at the level of the interface. The board
setting can be adjusted so the LED is ON or OFF (JP3/JP11) when the interface is detected.
1.
Determine Normal Process Condition
2.
Decide whether relay is energized or de-energized at normal conditions
3.
Determine if T.C. (Thermal Conductivity) is high or low at normal conditions. Measure change in voltage (P2 pins
1,3) - higher voltage is lower T.C.
4.
Based on above data and choices, See section 3.1 or 3.2.
16 TX Thermal Disperson Level Switches | Operating instruction manual