95-8533
5-2
18.2
NOTE
Electrochemical sensors have a finite
lifespan. If a successful calibration
cannot be performed, inspect the
hydrophobic lter. If the lter is plugged,
replace it and recalibrate the sensor. If
the filter is in good condition, replace
the sensor. Recalibrate following the
procedure described in the “Calibration”
section.
CALIBRATION AND
ADJUSTMENTS
To ensure optimum performance, calibration
must be performed on a regularly scheduled
basis. Since each application is different, the
length of time between regularly scheduled
recalibrations can vary from one installation
to the next. In general, the more frequently a
system is checked, the greater the reliability.
IMPORTANT
4–20 mA devices not manufactured by
Det-Tronics must be pre-calibrated. To
ensure adequate protection, calibration
must be performed on a regularly
scheduled basis.
NOTE
If the calibration procedure is not
completed within 12 minutes, the
detector will revert back to the previous
calibration values. The red LED will blink.
The calibration will be logged as aborted.
NOTE
The “Sensor Replacement” calibration
procedure must be used for the initial
calibration of a new sensor. The “Routine
Calibration” procedure can be used for
all subsequent calibrations.
NOTE
Some calibration procedures require
the operator to activate the reed switch
located on a circuit board inside the
junction box. See Figure 5-1 for reed
switch location. To activate the switch,
hold the calibration magnet against the
side of the junction box near the switch
location approximately one inch above
the mounting surface. (Do not open
the junction box.) Hold the calibration
magnet in place for approximately
four seconds to initiate the calibration
procedure.
CALIBRATION ALGORITHM A
FOR MANUAL CALIBRATION OF
UNIVERSAL DCU
Normal Calibration
1. Activate the reed switch. (The red LED
blinks while the reed switch is closed.)
2. After the reed switch has been closed for
three seconds, the calibrate LED blinks,
indicating it is ready for the zero input.
3. Enter the zero input (4 mA).
4. Activate the reed switch. (The red LED
blinks while the switch is closed.)
5. After the reed switch has been closed
for three seconds, the communication
module records the uncalibrated value
in the calibration log and calibrates the
zero value. (The calibrate LED stays on
steady.)
6. Apply the calibration gas.
7. The calibrate LED blinks as the input
increases.
8. Activate the reed switch. (The red LED
blinks while the reed switch is closed.)
9. The communication module records the
uncalibrated value in the calibration log
and calibrates the span value after the reed
switch is on for three seconds.
10. The calibrate LED stays on steady.
GND
9 107 85 63 41 2
13 1411 12
A188
MAGNETIC REED SWITCH *
*
TO ACTIVATE THE MAGNETIC REED SWITCH,
HOLD THE CALIBRATION MAGNET AGAINST THE SIDE OF THE ENCLOSURE
AT THE LOCATION OF THE REED SWITCH,
APPROXIMATELY ONE INCH ABOVE THE MOUNTING SURFACE.
SW1
Figure 5-1—
DCU Terminal Wiring Board Mounted in Six-Port Junction Box
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