Fiber optic Linear Heat Detection (LHD)

A Linear Heat Detection (LHD) system is designed to monitor and detect changes in temperature along the length of a sensor cable. A fiber optic LHD uses standard fiber optic sensor cables, typically over lengths of several kilometers, that function as linear temperature sensors. These systems are truly distributed, i.e. respond to heat at any point along the cable equally. The result is a continuous temperature profile along the entire length of the sensor cable.

The Technology Behind Fiber Optic LHD

The LHD measurement principle is based on the Raman effect. An optical laser pulse emitted from the LHD interrogator travels through a single optical fiber. Light is scattered back to the transmitting end, carrying temperature information along the route of the sensor. The position of the temperature reading is determined by the arrival time of the returning light pulse. AP Sensing’s patented code correlation technology enables outstanding system reliability, accurate measurements and high performance.

Video: How does Raman Reflectometry Work?

Benefits of fiber optic LHD

✓ An easy-to-install, single passive cable

✓ Immune to electromagnetic interference (EMI)

✓ Maintenance-free (invaluable for inaccessible areas)

✓ Cost-effective (long distance coverage)

✓ Precise location of events

✓ Monitoring of fire size and spread

Fiber optic LHD allows smart alarm configuration

✓ Five different alarm criteria for quick detection

✓ Flexible zone and alarm configuration

Comparison of LHD Systems

Unlike traditional fire detection systems, a fiber optic based LHD solution detects fires or hotspots quickly and precisely identifies their location within a few meters.

Fiber Optic LHD Multipoint LHD Analog LHD Digital LHD
Lightweight Cable, Simple Installation
Simultaneous Detection of Multiple Events
Resettable Detector
Flexible Alarm Parameters
Flexible Zoning
Gapless Temperature Measurements

 

Learn more about the new standard for fiber optic LHD - the N45-Series