Det-Tronics R8471NH34001,2,3 Single Channel Gas Controller, NH3 - Manual (Page 23)

21 95-8529 1.1
Section IV
System Maintenance
ROUTINE MAINTENANCE
OUTPUT DEVICES
All external equipment that is connected to the
controller should be maintained according to the
manufacturer’s recommendations.
CHECKOUT IN NORMAL MODE
The system should be checked periodically in the
Normal mode to ensure that those items not checked
by the controller diagnostic circuitry (such as output
relays) are functioning properly.
CAUTION
Be sure to secure all output devices that are
actuated by the system to prevent unwanted
activation of this equipment, and remember
to place these same output devices back into
service when the checkout is complete.
SENSOR CELL REPLACEMENT
NOTE
Verify that no hazardous conditions exist or
remove power from the sensor prior to replacing
the sensor cell (unless an I.S. barrier is used with
an intrinsically safe sensor).
To replace the sensor cell:
1. If the controller will remain powered during sensor
cell replacement, enter the sensor replacement
mode before replacing the cell.
NOTE
The sensor replacement mode inhibits all
controller outputs to allow replacement of the
sensor cell without removing power from the
controller. In addition, this mode automatically
sets the factory default values for sensor
calibration. Alarm setpoints and calibration time
are not affected.
CAUTION
Upon entering the Sensor Replacement mode, all
previously entered sensor calibration information
is lost. Sensor calibration must be performed,
even if the sensor cell was not replaced.
To enter the Sensor Replacement mode, press and
hold the Reset button for approximately 9 seconds
until the digital display begins flashing and the CAL
LED is illuminated. Release the Reset button.
2. Press the Set button. The FAULT LED also comes
on. The controller is now in the Sensor Replacement
mode.
3. Remove the cap from the sensor base. See Figure
5. (There is no need to remove the sensor housing
from the junction box.)
4. Remove and discard the old sensor cell. Check for
corrosion or contamination on the terminals on the
sensor base, and clean if necessary.
5. Determine proper orientation for the new cell, then
carefully plug it in.
NOTE
Handle the sensor cell carefully. To avoid
possible damage, observe the normally accepted
procedures for handling electrostatic sensitive
devices. See form 75-1005 for additional
information.
6. Be sure that the O-ring on the sensor housing is
in good condition, then place the cap back on the
sensor base. Tighten only until snug.
Do not over
tighten.
7. If power was removed prior to replacing the sensor
cell, re-apply power. Allow time for the unit to warm
up and stabilize, then calibrate.
NOTE
If power was removed from the controller during
the sensor cell replacement procedure, the
controller will automatically return to the Normal
mode when power is restored (after a time
delay). To prevent the possibility of alarms, allow
the system to warm up in the sensor replacement
mode. The sensor replacement mode can
be entered during the power-up time delay by
holding the Reset button for 7 seconds.
Press Reset to exit the Sensor Replacement mode.
The controller will automatically enter the Normal
mode.
A Recommended Test Form is supplied at the back of
this manual for recording maintenance performed on
the system.