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2. Installation
Xgard Type 4
2.2 Mounting
Xgard
should be installed at the designated location with the sensor
pointing down. This ensures that dust or water will not collect on the
sensor and stop gas entering the cell. The mounting detail is shown in
Diagram 2. Care should be taken when installing the detector to avoid
damaging the painted surface of the junction box and sensor retainer.
2.3 Cabling requirement
Cabling to
Xgard
must be in accordance with the recognised standards
of the appropriate authority in the country concerned and meet the
electrical requirements of the detector.
Crowcon recommend the use of steel wire armoured (SWA) cable and
suitable explosion proof glands must be used. Alternative cabling
techniques, such as steel conduit, may be acceptable provided
appropriate standards are met. The cable selected must be suitable for
use in temperatures of up to 150°C (302°F).
Maximum permissible cable lengths depend on the cable resistance and
sensor being used. It is important that the correct bridge voltage be
applied to the detector. This will vary depending on the part number of
the sensor fitted (see ‘Sensor type’ on the label fitted to the junction box).
Table 5 below summarises the bridge voltage requirements.
Detector
Pellistor
Bridge Volts
Comment
Part No.
Type
(Vdc)
S011954
VQ21T
2.0
Poison resistant
Table 5: Bridge voltage settings