'TH' Digital - Product Specification

1.0 'TH' Digital Linear Heat Detection

1.1 The linear detection system to be installed is to be of the "digital" operating concept whereby at a pre- selected temperature an alarm signal is generated by the two conductors moving into contact with each other.  In the event of mechanical damage to the sensor cable a fault signal will be generated by loss of conductor continuity monitored by "remote" end of line resistor. No site calibration should be necessary with the alarm temperature rating pre-specified from the range 68C/155F, 88C/190F, 105C/220F. Maximum acceptable alarm temperature tolerances are+/-4C (+/-7F). The sensor cable should have been F.M. tested to verify capability of withstanding continuous exposure to ambient temperature to minus 40C (-40F).

1.2 Unless otherwise specified in writing by the local authority having jurisdiction, a minimum +11C (20F) differential must exist between maximum normal operating ambient temperature of the area/s in which the sensor cable is to be installed and the minimum alarm temperature rating of the sensor cable. This conforms with UL521 section 53.7 and is to ensure the avoidance of potential false alarm signals resulting from normal local ambient temperature variations.

1.3 The specified alarm temperature of the heat sensor cable is not to be dependant upon the total length of sensor cable installed or upon any manufacturer specified minimum length being exposed to any overheat/fire condition.

1.4 For "area" protection applications the maximum spacing between sensor cable runs should be up to 10.6m/35 feet.

1.5 Sensor cable construction is to consist of a twisted pair of 0.912 mm (0.036 in) tin plated copper coated steel conductors each extruded with 0.294 mm (0.011 in) temperature sensitive polymer with an outer extrusion of colour coded class 43 PVC based polymer (meeting UL 1581 1090.1/1090.2 propagation and self extinguishing requirements).

1.6 The overall sensor cable external diameter is to be 3.5 mm (0.138 in). Where required for the risk to be protected, additional corrosion and abrasion protected extrusion is to be supplied on the sensor cable - increasing its diameter to 4.0mm (0.157in).

1.7 The outer extrusion is to be colour coded for ease of alarm temperature rating identification. Alarm temperature rating is to be repeatedly and indelibly marked at regular intervals along the sensor cable together with manufacturing batch i.d. and approvals granted.

1.8 Sensor cable conductor Resistance should not be greater than 92 ohms/km thereby increasing the zone length potential for Integration with resistance sensitive existing central fire control systems in the event no sensor cable manufacturer supplied dedicated interface unit is specified.

1.9 The sensor cable is to be suitable as a minimum for installation within external local weather conditions unless more severe environmental conditions are specified in detail prior to sensor cable supply and installation.

1.10 The linear heat sensor cable specified and installed is to be Factory Mutual (FM) Approved AND Underwriters Laboratories (U.L.) Listed.

1.11 The digital linear heat detection system offered should also include the option for the provision of a dedicated interface unit (2000 metres sensor cable connection per interface or greater) supplied complete with colour coded LCD display alarm point location facility to aid identification on applications where detection and alarm signal may precede visible flame.