Patol   Linear Heat Detecting Cable - Page 2
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Principles  
STEEL CONDUCTOR - COPPER CLAD 

INNER INSULATION / DIELECTRIC - PVC 

BRAID LAYER - TINNED COPPER WIRES 

OUTER SHEATH - RED PVC

 
The Line Heat Detector 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. 
The primary mechanism of heat (fire) detection is that the resistance of the dielectric,  monitored between the central conductor and braid layer, has a negative temperature coefficient (NTC).
 
This NTC characteristic is a logarithmic function,  and thus the resistance at normal ambient temperatures is very much greater than at abnormal alarm temperatures. 
There are other parameters exhibited by the cable such as capactive type effects. The cable must be employed in conjunction with the correct type of monitoring unit. 
When correctly configured considerable lengths of the detector may installed whilst maintaining the ability to trigger alarms for 'Hot Spots' on small sections of the detector cable. 
Refer to 'Characteristics as a Fire Sensing Cable' .
 
Applications
  • Cable Tunnels, Ducts & Mezzanines
  • Escalators & Moving Walkways
  • Petro-Chem Storage Tank Rim Seals
  • Paint Shops & Spray Booths
  • Conveyors - Coal, Wood, Sulphur, etc..
  • Ceiling Voids & Attic Spaces
  • Marine Engine Rooms
  • Nuclear Reactor Plant Areas
  • Electrical Switchgear Cabinets
  • High Rise Warehouse Pallet Racking
  • Oil Rigs & Off Shore Platforms
  • Fume Cupboards & Glove Boxes
  • Grain Silos & Agricultural Storage
  • Vehicle Engine Compartments
  • Steam Pipe Leaks & Trace Heating Faults
  • Product Lines - Flanges, Valves & Pumps
  • Computer Room Under Floor Voids
  • Road & Rail Tunnel Carriageways & Sumps


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The Line Heat Detector is employed in conjunction with an 'end of line' terminating device (EOL Terminator) and a zone monitoring unit or control panel equipped with an appropriate LHDC interface channel. 
The cable may be installed in Hazardous Areas by means of Intrinsically Safe Zener Barriers. Similarily, when the protected area is remote from the monitoring equipment 'interposing' cables may be employed. (Contact Patol for reccommended types). 
LHDC is versitile in that it can both provide an alternative to point heat detectors in conventional (space) protection situations, and it may also be readily installed in very close proximity to monitored hazards. 
The detector is paticularily suited to applications where harsh environmental conditions preclude the use of other forms of detection. 
The low maintenance requirement of the detector provides a unique solution to fire detection in areas that have access restrictions due to either physical difficulties or personnel health risk.
   PATOL LIMITED - Rectory Road, Padworth Common, Berkshire, UK.   Tel: 0118 9701701   Fax: 0118 9700700
   Email:- patol.limited@ntlworld.com    info@patol.co.uk