linear heat detection
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| Typical detecting temperature
| 68 °C{{cite web|title=Linear Heat Detection cable information|url=https://www.tyco-fire.com/TFP_common/TFBP_LHD_Slick.pdf|accessdate=26 April 2014}} (building) | 180 °C (plant) |
|---|
| Maximum length
| 3000m{{cite web|title=Linear Heat Detection cable information|url=https://www.tyco-fire.com/TFP_common/TFBP_LHD_Slick.pdf|accessdate=26 April 2014}}{{cite web |title=Safe Fire Detection, LHD Information |url=http://www.safefiredetection.com/pages/What_is_LHD.htm |publisher=Safe Fire Detection |accessdate=26 April 2014}} |
Linear heat detection (LHD) (also known as linear detection wire or linear heat detection cable or linear heat) is a very commonly used method of fire detection. It can detect a fire anywhere along the length of the cable, and can be of lengths in excess of a kilometer.
Applications can range from building fire alarm systems to mobile plant machinery.
Operation
Linear heat detection (LHD) cable is essentially a two-core cable terminated by an end-of-line resistor (resistance varies with application). The two cores are separated by a polymer plastic, that is designed to melt at a specific temperature (commonly 68 °C for building applications{{cite web|title=Linear Heat Detection cable information|url=https://www.tyco-fire.com/TFP_common/TFBP_LHD_Slick.pdf|accessdate=26 April 2014}}), and without which causes the two cores to short. This can be seen as a change in resistance in the wire.
There are a limited states the LHD cable can be in:
- Open-circuit - effectively an infinite resistance
- Fire detection - resistance of the linear heat cable to the short circuit
- Normal operating condition - apparent resistance will be the same as the end-of-line resistor
See also
References
{{Reflist}}
External links
- [https://www.nwfiresolutions.co.uk/ Fire Safety Management]
Category:Active fire protection