Siemens FDT 421 Intelligent Thermal (Heat) Detector

The Intelligent Thermal (Heat) Detector (Model FDT421) provides an advanced method of detection, address programming supervision ─ combined with sophisticated FACP communication. Model FDT421 uses a state-of-the-art thermistor, microprocessor and advanced signal analysis, providing high reliability and accuracy. Additionally, Each Model FDT421 unit is UL listed including advanced built-in ISOtechnologyTM - a “True Class-X” SLC operation (use is optional) greatly improving system reliability and circuit integrity while providing advanced addressable fault finding. Each model FDT421 is a cost-effective, two-wire / addressable thermal detector that provides a distinctive, advanced feature: seven (7) field-selectable temperature settings specially tailored for application-specific detection needs combined with Class-X SLC operation built-in avoiding additional installation and material cost. The temperature-range settings for each Model FDT421 detector is between 135°F (57°C) ─ 175°F (79°C) with fixed and rate-of-rise programmability. This variance provides the customer with maximum flexibility to program the temperature settings to suit multiple application needs and changing environmental conditions. Model FDT421 can be configured to provide a low-temperature warning signal at 40°F (4.4°C). This feature − along with a compatible FACP (Desigo Fire Safety Modular | FireFinder XLS/V or with Desigo FC /FV2025 or FC /FV2050 FACPs) − serves as prevention of water freezing in pipes for sprinkler systems, meeting NFPA 72.