What is LHS or linear heat sensing cable?
Linear Heat Sensing cable (LHS), an intelligent cable, detects heat and notifies the fire brigade as regards an impending fire disaster and/or extinguishes fire by activating a set of associated fire protection equipment installed in designated areas that are to be protected.
LHS cables, which work as sensors, detect fire at a very early stage and send signals to fire alarms and other fire protection devices. Linear heat sensing cables are capable of detecting heat over their entire length. These cables sense a change in temperature with the help of their specially made temperature-sensitive insulation. When a fire breaks out, the temperature of the insulation around the LHS cable rises. As the temperature reaches the rated temperature, the special grade insulation material melts. This results in a short circuit because of the two tin-coated conductors passing through the common insulation sleeve of the cable coming into contact with each other. The short circuit, in turn, triggers off a fire alarm. The LHS cables are generally used in conveyor belts, aircraft hangers, tunnels, rim seal fire protection systems installed in floating roof tanks, cable trays, and metro rails for fire detection and protection.
What is the standard temperature rating of Linear Heat Sensing cables?
Linear heat sensing cables are available in different temperature ratings such as 68, 88, 105, 138, and 180 degrees Celsius. The advanced polymer used in linear heat sensing cables along with digital technology enables the detection of high temperature along the entire length of the cable. LHS cable is made by twisting a pair of zinc-coated spring steel conductors and enclosing them in a temperature-sensitive thermoplastic polymer sleeve. When the temperature in a protected area rises and exceeds the rated temperature of the insulation of the LHS cable used the polymer melts and the conductors come into contact with each other and this leads to a short circuit. This, in turn, triggers an alarm to warn people working in the area.
What are the applications of LHS Cables?
Fire protection in food-processing industries
The ambient temperature in food processing factories is always high. A short-circuit or friction in any of the machinery can lead to a fire because of the high temperature at which foods are prepared or due to the oil fumes. As fire, smoke, and gaseous fumes will always be present in factories where food items are being processed, it is not practical to use flame detectors, smoke detectors, or aspirating type smoke detectors.
As there will be fewer operators in highly mechanised factories, the information about a fire breakout reaches the fire brigade very late. By the time the information reaches them, the expensive food processing machinery would have been completely damaged. A fire alarm or a fire protection system that can be effectively used in food processing units is the Linear Heat Sensing Cable. However, the LHS cable installed in a food processing unit should have the right temperature rating depending on the ambient temperature of the unit. Fire protection systems Linear heat sensing cables are designed by fire protection system design engineers trained in India’s best fire protection training institutes.
Best fire protection system for conveyor belts
Conveyor belts are usually used for handling materials like coal, lignite, petrochemical products, polymers, PVC, etc., that can easily catch fire. An increase in temperature because of broken bearings and worn-out gears, or friction can result in the conveyor belt, or the inflammable material being handled can catch fire. As the possibility of the presence of dust is very high in conveyor belts, it is impractical to install traditional smoke detectors and aspirating type smoke detectors. Linear Heat Sensing Cable based fire protection system is the best option in such situations.
Fire protection in cable trenches and cable trays
In large factories, refineries, and petrochemical plants, electrical cables are drawn through trenches and cable trays. Damage to any of the cables can lead to an internal short-circuit and a fire accident. It will take a long time to know about a fire that broke out in a cable trench. As such, it could result in huge losses. A solution to this problem is the linear heat sensing cable-based fire protection system. The LHS cables tied to the power cables trigger an alarm when the cables catch fire and cause the electrical circuit breaker to trip. This way it is possible to prevent heavy damages and losses.
Fire protection systems in car parking areas
LHS cables are the best-suited sensors for car parking areas. The advantage of using these cables is that they are not damaged because of continuous exposure to sunlight and rain. Traditional sensors cannot be used in car parking areas as exhaust from vehicles and the presence of carbon monoxide fumes can set off false alarms. That’s why linear heat sensing cable is widely used in such areas.
Fire protection systems in recycling plants
In recycling plants, gaseous fumes and flames will be present because of the use of conveyors, furnaces, and boilers. As a result, it is not recommended to use traditional heat, smoke, and flame sensors. In such areas, linear heat sensing cables can be used without any problems. As these cables are both weather and waterproof, they are good for outdoor use as well. This is the main reason for using LHS cable based fire protection systems in recycling plans. Fire protection systems for recycling plànts are designed by professionally trained engineers, who are trained to make fire protection systems with linear heat sensing cables in India’s best fire protection training institutes.
Which companies manufacture LHS or linear heat sensing cables in India?
The top companies in India that manufacture and market LHS cables are System Sensor, Honeywell, Ravel, Hochiki, and Alankar cables.