Gas Sensing Cell Replacement; Removing The Detector Main Board; Replacing The Sensor - GasTech D-Guard2 Operator's Manual

17.3. Gas sensing cell replacement

As described in section 11.1, electro-chemical sensing cells will eventually diminish in their capacity to accurately
detect its target gas. Infra-Red sensors, although more likely to last several years, may become unserviceable due to
contamination. Once this occurs, the sensing element will need replacement.
Sensor replacement should only be carried out by Gastech service staff or appointed agents.
Sensors must only be replaced with the same type. Fitting substitute brands of sensor may cause the
detector to operate unreliably. Fitting sensors of a different type will likely cause the detector to seriously
malfunction or become damaged. Substituting sensors for non-GasTech approved parts or incorrect types
will void the product warranty. Gastech will not accept liability for any adverse outcomes that may arise
as a result of fitting inappropriate sensor types to D-Guard
17.3.1

Removing the Detector Main Board

To gain access to the sensor, follow the steps given below.
Note ensure that this is only done by a suitably trained or qualified person. Disassembly of D-Guard
not be carried out in a hazardous area.
It is strongly advised to wear an antistatic wristband and use an antistatic mat to place the detector PCB
onto when working on replacing the sensor.
Remove the four lid retaining screws.

Unplug the power cable from its PCB socket.

Lay the detector lid face down and observe the four PCB fixing screws.

Remove the four PCB fixing screws and turn the main board over.

Operate with caution so as not to damage any component or scratch the display.
Do not get fingerprints on the display face as these will be difficult to remove.
17.3.2

Replacing the Sensor

Unplug the old sensor and replace with a new sensor of identical type.

Reverse the process of disassembly to restore the detector to a fully assembled state.

Once a sensor has been replaced, a full re-calibration of the detector is necessary return the performance to its stated
specification. At the same time the cell is replaced, the water repellent membrane that protects the gas entry port,
should be inspected and replaced if required.
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