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Calibration Handbook
WARNING
When the XNX transmitter is placed in Inhibit Mode, alarms are silenced. This will prevent an actual gas event
from being reported. Inhibit Mode must be limited to testing and maintenance only. Exit Inhibit Mode after
testing or maintenance activities.
Using the Calibration Cup
1. Snap the calibration cup into the weather protector. The two protrusions on the cup fit into recesses in
the weather protector.
2. Attach the hose from the gas cylinder to the calibration cup. Note that the cup's flow is unidirectional.
There is an arrow on the bottom showing flow direction
3. Adjust the calibration flow rate
weather
protector
calibration cup
1
300-375 ml/min for XNX EC sensors, 500 ±200 ml/min for XNX mV sensors, unless otherwise directed
Zero and Span Calibration of XNX EC Hydrogen Sulfide (H
CAUTION
Before initial calibration, allow the sensor to stabilize for 30 minutes after applying power. When in zero and
span calibration modes, the current output from the sensor is inhibited (default 2mA) to avoid false alarms.
Recalibrate if the temperature of local environment has varied by more than ±15°C from the temperature of
calibration.
Hydrogen Sulfide sensors can be affected by extreme humidity changes. A sudden increase in ambient humidity
can result in a short-term positive drift in the instrument's reading. A sudden decrease in ambient humidity
can result in a short-term negative drift in the instrument's reading. These are most likely to be noticed during
calibration with dry or cylinder gas.
When calibrating hydrogen sulfide cartridges, the following should be taken into account
1. To zero the sensor, use a compressed gas cylinder of 20.9%Vol oxygen (not nitrogen). Do not use
background air.
If a span calibration is to be performed, the span calibration gas should be applied to the sensor immediately
1
.
attach gas
cylinder hose
150
S) Sensors
2
XNX Universal Transmitter
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