MANUAL
CT
Controllers
OPERATION
Page 33
1.4 - Low Alarm
The ALARM LOW value is set to generate an alarm when the
sensor reading falls below the set value. After the alarm value
is set, the ALARM OPTIONS submenu 1.4.1 is shown, asking
whether a low alarm condition should stop the dump valve and
activate the alarm buzzer.
1.5 - High Alarm
The ALARM HIGH value is set to generate an alarm when the
sensor reading rises above the set value. After the alarm value
is set, the ALARM OPTIONS submenu 1.5.1 is shown, asking
whether a high alarm condition should stop the bleed valve and
activate the alarm buzzer.
1.6 - Time Limit
The TIME LIMIT sets the maximum amount of time in minutes
that is allowed for continuous dumping of water to correct a high
conductivity or TDS reading. This acts as a safety feature to
prevent overdumping of water in case of a malfunction of the
dump valve.
1.7 - Run Time
The RUN TIME displays the amount of running time in minutes
for each current activation event and the cumulative run time
since last reset to zero.
To reset the cumulative run time, enter zero in the last column.
To reset only the current run time, turn the control mode off and
back on.
After the cumulative run time is reset, the TOTAL TIME ALARM
submenu (see submenu 1.7.1) is displayed to set the Total
Time Alarm option. This alarm is activated when the cumulative
run time reaches the alarm value. It does not lock the bleed
control outlet.
1.8. - Select Scale
The Select Scale prompt takes the operator to the SELECT
SCALE Submenu 1.8.
1.8.1 - Cell Constant
Conductivity is usually monitored with contacting-type sensors,
which are made of two electrodes that are specifically sized and
spaced to provide a known cell constant or factor.
The Cell Constant corresponds to the aspect ratio (in cm
-1)
of
the geometrical cell formed by the two electrodes (length
divided by cross sectional area). It is set on the
CHEMTROL®
CT
Controller
, as specified by the probe
manufacturer.
To check the cell constant, measure the conductivity of a water
sample with a portable meter. Divide by the conductivity
reading on the CHEMTROL®
CT
Controller
. Make sure
both instruments are consistent in using or not compensation.
Submenus 1.4.1 and 1.5.1
Submenu 1.7.1
Submenu 1.8
1.8.2 - TDS Factor
The TDS Factor is the conversion factor used to convert from
conductivity readings (in
µ
S/cm) to Total Dissolved Solids
concentrations (in ppm or mg/l). Entering a TDS Factor
different from 1 automatically changes all readings and displays
from conductivity to TDS.
Because the conductivity of ionic species varies with the type of
electronic charges, the relationship with TDS is to a large extent
empirical.
For most water treatment applications, the TDS factor is about
0.5. For instance, a Sodium Chloride solution with a
conductivity of 2,764
µ
S/cm contains 1,410 ppm (mg/l) of NaCl.
This indicates a TDS factor of 1,410 divided by 2,764, i.e. 0.51.
SELECT SCALE
Cell Constant
1.00
TDS Factor
0.50
ALARM OPTIONS
Bleed lockout
YES
Alarm Buzzer
YES
TOTAL TIME ALARM
Alarm if total
Bleed time exceeds
110 min.
Enter 0 for no alarm