Linear Heat Detection

Linear Heat Detection (LHD) Systems are cable-based systems that provide economical temperature monitoring at the precise point of risk. The systems are reliable, flexible and have the ability to detect abnormal temperature variance before fire breaks out. The comprehensive LHD portfolio allows a wide range of commercial and industrial fires and overheats risks to be protected, in ambient temperatures of -40°C to +200°C. It is ideally suitable to be installed parallel to the fire risk, provides localized detection which is more effective.

The LHD is provided with chemical and mechanical protection making it suitable for all areas, especially for confined areas or harsh environment, where other types of detector are not an option. It is particularly suitable to protect areas against ‘debris’ fire, such as lift pits, escalators and electrical risers.

In some cases, the main cause of fires is due to overheating cables in cable trays. These areas generally located in restricted space and consist of a number of cables running side by side. They are difficult to access and potentially leading to undetected fire spread. Therefore early detection of an overheat condition is necessary to prevent a major disaster.

Digital Cable employs a twin conductor switching cable. It operates by melting of internal insulation between the conductors at a predetermined temperature. This results in a short circuit which provides a fire alarm signal. Fault conditions are detected by continuous monitoring for an open circuit state.

Optional location device provides location of alarm point along the length of sensor cable.

Analogue Cable consists of four cores. The two cores with clear outer coating consist of a copper conductor coated in a temperature sensitive polymer whose resistance changes as a function of temperature. Another two cores with white and red outer sheath provides calibration resistance and monitors average ambient temperature respectively.

The control unit monitors the resistance of the specially doped polymers within the sensor cable. An abnormal change in the resistance along the detection cable triggers either pre-alarm or alarm conditions on the control unit.