Dräger X-node Technisches Handbuch Seite 71

6 Calibration
During calibration, the measurement accuracy of the sensor is monitored and adjusted with a known test
gas concentration. First, the zero point and then the sensitivity of the sensor is calibrated. The duration
of the calibration intervals depends on the respective regional or operational standard requirements.
In order to ensure proper operation, never set the sensitivity before the zero point has been set. If these
processes are carried out in the wrong order, the calibration will be incorrect.
WARNING
Incorrect calibration
An incorrect calibration can lead to inaccurate measured values.
► After changing the sensor, check all settings and parameters.
► Test a newly installed sensor with target gas in order to ensure it is operating correctly.
6.1 Test gases
Test gas properties (e.g. relative humidity, concentration) can be found in the corresponding sensor data
sheet. Depending on the type of calibration, various test gases are used.
Zero gas
The zero gas is a test gas which is used to calibrate the zero value. If the ambient air is free from
unwanted contaminations and measured gases, it can be used as a zero gas.
For O
possible. Here, the display must show < 0.6 Vol% after 3 minutes.
Calibration gas
The calibration gas is a test gas used to calibrate sensor sensitivity during a span calibration. The
calibration gas is a known concentration of the measured gas, diluted with fresh air or nitrogen. For O
sensors, no calibration gas is required as oxygen from the ambient air is used.
6.2 Preparing the test gas supply
The test gas must be fed unpressurised with a flow rate of 0.5 L/min.
Prerequisites
– Warm-up phase of the sensor has been completed.
– Time and date are set (see "Setting the time and date", page 67).
Work equipment
– Test gas cylinder with pressure reducer, for aggressive gases with stainless steel pressure reducer
– Calibration adapter with hose nozzles (order no. 68 10 536)
– Hose, type depends on gas properties (e.g. FKM hose, order no. 12 07 068)
DANGER
Health risk from test gas
Inhalation of test gas is a risk to health and can even cause death.
► Do not inhale test gas.
► Take note of the dangers associated with test gas as well as the hazard warnings and safety advice
(see, for example, safety data sheets, instructions on the test equipment).
WARNING
Triggering of alarms by test gas
The continued supply of test gas can trigger alarms.
► Make sure that the supply of test gas has been terminated.
1. Connect the calibration adapter (Fig. 1/2) and test gas cylinder (Fig. 1/1) with the hose.
2. To discharge the test gas, connect a hose to the second port of the calibration adapter.
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Technical manual Dräger X-node
sensors, nitrogen (N ) is used as zero gas. For O
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Calibration
sensors, only a zero point check is
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