Analogue Linear Heat Detection Cable
Analogue LHDC is designed to provide early detection of fire and overheating in circumstances where other forms of detection would not be viable, either due to inability to sustain the environmental requirements or through prohibitive costs.
Extensive single zonal lengths of the LHDC may be installed with the ability to trigger alarms for hot spots occurring on very small sections of the overall cable and providing the LHDC has not been subjected to excessive temperatures, the alarm condition can be reset at the zonal controller. This is particularly useful for maintenance annual testing and can be tested using the Patol proprietary one metre test oven.
Analogue LHDC is a coaxial cable constructed with a copper coated steel central conductor, an inner insulation (dielectric), a tinned copper braid layer and an overall protective sheath. Additional over sheaths are available for mechanical protection with Stainless Steel armour and nylon to provide resistance to Chemicals and Ultra Violet radiation.
The primary mechanism of heat (fire) detection is that the resistance of the dielectric is monitored between the central conductor and braid layer, which has a negative temperature coefficient (NTC).
Analogue cable is employed in conjunction with an end of line terminating device for continuity monitoring and a zone monitoring controller providing adjustable alarm thresholds and Fire and Fault outputs.
LHDC in Hazardous Areas
LHDC is suitable for use in hazardous areas by means of intrinsically safe (IS) zener barriers and the controllers located in the safe area. Similarly when the protected area is remote from the monitoring equipment, interposing cables may be employed between the monitoring equipment and the LHDC.
|LHDC in Hazardous Areas by means of Intrinsically Safe Barriers|