The MD9902-Ex flame detector is designed for harsh environments and areas prone to explosions. It is an addressable automatic detector capable of providing a fire alarm upon detecting flames. The detector can transmit the alarm to the Control Unit, signal the alarm through a high-intensity red LED, and indicate alarms and failures by switching two relays.
The fire detection system utilizes infrared sensors suitable for detecting fires involving liquids, combustible gases, and open fires with smoke from materials like wood, plastics, gas, and petroleum products. The evaluation involves three infrared detectors operating on different wavelengths, protected by a sapphire glass acting as a filter.
The MD9902-Ex employs a microprocessor for electronic signal analysis. The triple IR flame detector uses an additional criterion, analyzing flame flicker-frequency to enhance accuracy. It offers good false alarm rejection capabilities against interfering radiations and sunlight.
Encased in an explosion-proof aluminum enclosure, the detector ensures watertightness and protection from electromagnetic interference. Electronic components are shielded from moisture through epoxy resin potting, providing mechanical robustness. The detector continuously checks its electronic circuits and signals faults or failures.
Communication with the Control Unit occurs through LCU and BCU control boards, supplying modulated 24Vdc power for data transmission with the MD2 protocol. The address is assigned by software via the Control Unit. In the event of Control Unit failure, the detector enters a “degraded operation” status, still sending a digital signal during alarms.
The optical window features a flashing red LED in the alarm state. Additionally, the detector signals alarms and faults by switching two potential-free SPDT contacts. A line protection circuit guards against short circuits, isolating the affected area and allowing the rest of the loops to operate normally. Two LEDs (A and B) indicate loop short-circuit status on the board.
