9. The sensor calibration has been successfully completed
10. While the gas from the sensor housing is being cleared the 4-20mA analog output
will be held at 2.0mA and alarm relay will not be activated until the sensor has
cleared. Once cleared the unit will return to its normal operation. The 2mA level
on the analog output line is an indication to any connected gas monitor that the
sensor is in calibration mode thus avoiding any false alarm.
Also refer to “Sensor calibration Flow Chart” for quick calibration review and
“Calibration Error and remedies”
Calibrating Oxygen Depletion Sensor
The sensor is calibrated with 20.9% oxygen present in air to set the span and pure
nitrogen to purge. If ambient air is contaminated and the level of oxygen is not
20.9% then the sensor must be purged with fresh air before the calibration switch is
activated. Once the calibration is initiated the alarm relay will be deactivated and
the 4-20mA analog signal will be held at approximately 2mA to avoid any false
alarm.
Follow the steps below to calibrate the sensor
.
1. Remove the rain / splash guard if attached.
2. Place the magnetic tool against the cover at 8 o’clock position to activate the
magnetic switch as shown in figure 7
3. Place and hold the magnet until LED display on the front panel starts flashing
. Move the magnet away from the cover.
4. While the display is flashing CAL the sensor is making its initial adjustments.
It may take 5 to 10 seconds. (Note: Do not nitrogen gas yet)
5. Once the initial adjustments are made the sensor starts displaying
(symbol for nitrogen) indicating to the user to apply the pure nitrogen gas to
the sensor. The display flashes twice every second.
6. The microprocessor waits 60 seconds for the user to apply the nitrogen gas
while flashing the display approximately twice every second. Attach the
calibration adapter to the sensor head assembly and turn the nitrogen gas on.
When the flow of the gas is detected by the sensor the display flashing rate
will slow down to once every second. If no gas is detected within 60 seconds
the sensor aborts calibration and will display E-3 error code “Calibration
Time Out” for few seconds before returning to normal operation.
PT295 Series Toxic Sensor Rev 5.1
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