Sierra Monitor Corporation 4501-05 - Manual (Page 18)

Model 4501-XX Toxic Gas Sensor Module
Page 14 of 35
6. CALIBRATION
6.1 CALIBRATION FREQUENCY
The sensor module must be calibrated every 180 days at a minimum. 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.
N OTE
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 “calibration aborted” 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 the gas of interest. When in doubt,
use a portable instrument to confirm that there is no background.
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.
NOTE: Refer to Appendix D for information on use of permeation tube for 4501-25 calibration.
6.3 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.
6.4 SENSOR EXPOSURE TO GAS
Calibration gas must be delivered to the sensor using the flow rate and
duration listed in below:
Model Calibration Gas Flow Period
4501-03 Air 300 cc of Zero Air or exposure to Ambient Air (3 minutes)
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)
4501-08* Chlorine 300 cc/min Until Stable (minimum 3 minutes)
4501-10 Sulfur Dioxide 300 cc/min Until Stable (minimum 3 minutes)
4501-12 Nitrogen Dioxide 300 cc/min Until Stable (minimum 3 minutes)
4501-25 Ammonia See Appendix D
4501-26** Chlorine 500 cc/min Until Stable (minimum 6 minutes)
* Note: Use 10 PPM Cl
2
to calibrate, equivalent reading = 3.0 PPM ClO
2
** Note: Use 5 PPM Cl
2
to calibrate equivalent reading = 8.0 PPM HF
Figure 6 - 1: Model
5358-01 Calibration
Adapter
Sample Gas In