50
1.1 Flameproof thermal conductivity type gas
detector
This version of
Xgard
is a Flameproof thermal conductivity type gas
detector, designed to monitor binary gas mixtures (such as hydrogen in
nitrogen, methane in carbon dioxide) in % volume concentrations. The
detector relies on there being a substantial difference in the thermal
conductivity properties of the gases in the mixture being monitored.
Precautions should be taken to ensure that humidity in the gas mixture is
kept to a minimum, and the operating temperature remains stable,
otherwise the sensor readings may be affected. For a list of gas mixtures
that can be detected using
Xgard
Type 6 please contact Crowcon.
Xgard
Type 6 is powered by 24 V dc (nominally) and provides a 420 mA signal
(sink or source) proportional to the gas concentration. The detector
is certified
II 2 GD EExd IIC T6, and is suitable for use in Zone 1 and
Zone 2 hazardous areas.
Electrical connections to the detector are made via the terminal block
on the PCB shown below.
Diagram 14:
Xgard
Type 6 PCB layout
(Shown with PCB cover removed).
1. Introduction
Xgard Type 6
VR3
Test
points
TP1
TP4
Srce
Sink
TP2
TP3
Supple
mental
external
grounding
terminal
(earth)
Internal
grounding
terminal
(earth)
