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Model 4501-XX Toxic Gas Sensor Module
6. CALIBRATION
6.1 CALIBRATION FREQUENCY
The sensor module must be calibrated every 180 days. Periodic functional tests are advisable for critical
applications and hostile environments.
The sensor module microprocessor software includes high-level self checking algorithms which provide
continuous sensor diagnostic and self adjustment.
6.2 CALIBRATION PREPARATION
Calibration of the sensor is accomplished by simple menu based steps and application of span gas.
NOTE
If an error is made during any stage of the calibration process, hold the magnet stick at the
[M] for 10 seconds. A scrolling display will indicate “Operate Mode” and the sensor module
will exit the calibration activity and return to normal operating mode. The calibration
procedure can then be restarted.
Calibration must be performed only when the area is known to be clear of Hydrogen Sulfide gas. When in
doubt, use a portable instrument to confirm that there is no background Hydrogen Sulfide gas.
For compliance with Factory Mutual (FM) Approvals, the Sierra Monitor Model 1250-01, 1260 -05 and 1260-45
are the FM Approved calibration gas delivery devices. Use the Model 5358-01 Calibration Adapter delivery
fitting.
Figure 6-1
Sample Gas In
Model 5358-01
Calibration Adapter
6.2.1 CALIBRATION GAS DELIVERY METHODS
Calibration gas can be delivered to the sensors via the Model 5358-01:
Calibration Adapter (Figure 6-1) - used with portable calibrators.
CALIBRATION PROCEDURE
The Calibration Menu is described on Table 6-1:
The procedure requires that the menu “keys” be activated using the magnet stick.
Each key press steps through the process of setting the zero value for clean air
and then setting the span value.
At each of these steps, apply calibration gas of the value corresponding to
the setting accepted on the sensor module display.
6.2.2 SENSOR EXPOSURE TO GAS
Calibration gas must be delivered to the sensor using the flow rate and
duration listed in below:
Model Gas Flow Period
4501-04 Carbon Monoxide 300 cc/min Until Stable (minimum 3 minutes)
4501-05 Hydrogen Sulfide 300 cc/min Until Stable (minimum 3 minutes)
4501-06 Chlorine 300 cc/min Until Stable (minimum 3 minutes)
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