13
Installation and Operating Manual
IP277, Rev DA
Mobrey MCU200 Series
February 2020
Figure 8. Sludge discharge control
A. Mobrey pipe section
B. MCU200 Series control unit
C. Sludge
This maintains the hydraulic pressure on the sludge to prevent release of dissolved gases. Any
such air entrained will give a false “thick sludge” indication.
The application of
Figure 8
shows a control valve opening on a timed basis to discharge the
sludge. After sludge is flowing along the line, the control valve can be closed by the MCU200
when sludge with a low density is detected.
The gain potentiometer on the control unit allows the percentage of solids to be adjusted to a
level that trips the output relay. A clockwise rotation of the gain increases the percentage.
Settled sludge discharge control
Reduce the time delay setting to make adjustments easier. See
“Relay output and LED logic
selection” on page 10
for details.
Set the operating frequency on the control unit to 1 MHz if the sensor is to operate at this
frequency. See
“Frequency selection” on page 9
for details.
With a sensor or pipe in relatively clean water (supernatant), set the gain switch to the
“LO” position and reduce the potentiometer gain until the LED changes.
See
“Gain switch (and potentiometer)” on page 9
for details.
Note this point on the potentiometer as the switching point for 0% suspended solids.
For a 1 MHz sensor on a 150 mm or 200 mm ID pipeline or sensor gap, working on primary
sewage sludge, each division increase on the potentiometer above the 0% switching point
represents approximately 1% suspended solids.
– Increase the potentiometer gain to the desired level, remembering a 2-division overlap
between “LO” and “HI” gain ranges.
A
B
B
C
