Chapter 2: Design and installation
10 Alarmline II Digital Linear Heat Sensor Cable Technical Manual
Design guidelines
The design and installation of an Alarmline II Digital Linear Heat Detection
system is unique to every site and application, therefore it is recommended that
this work is only undertaken by trained and competent persons following the
guidelines in this chapter.
There are two main types of protection that can be provided by the Alarmline II
Digital Sensor Cable:
Proximity detection: The sensor cable is installed close to the point of risk,
generally around the equipment to be protected. There is no specific design
criteria for these applications but there are guidelines to be considered.
Area coverage: The sensor cable is distributed throughout the risk area allowing
protection of the general area as opposed to specific points. Alarmline II Digital
Sensor Cable offers an alternative to point type heat detectors in this type of
application.
Proximity detection
• Selection of the appropriate sensor cable type is critical to ensure correct
performance of the system. The cable selection will be based on the
maximum possible ambient temperature within the risk area and the required
alarm temperature.
• The sensor cable should be installed close enough to the point of risk to give
an acceptable response, but not in a position where it can be damaged or
obstruct any moving parts. The location of the sensor cable should not restrict
access to any parts of the equipment which require maintenance.
• The thermal path to the sensor cable should not be obstructed and a
minimum distance of 25 mm should be left between the sensor cable and any
surface it is being mounted to.
• In outdoor applications, shield the sensor cable from direct sunlight to control
the ambient temperature around the cable and to prevent the risk of false
alarms.
• In hazardous areas, galvanic isolators or intrinsically safe (IS) barriers are
required to provide an IS circuit.
• Fixing of the cable will be determined by the application and the location at
which the cable is installed. Support the cable to prevent sagging. The
environmental conditions and clips to be used must considered.
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