The TSD 250 is a compact true duct smoke detector designed for direct smoke detection inside ventilation ducts without sampling tubes or built-in fans.
Featuring infrared smoke sensing technology, an SPDT relay output and Modbus RS485 RTU communication, it provides a cost-effective solution for HVAC ventilation systems and Building Management Systems (BMS).
Key Features
- Direct smoke detection inside ventilation ducts
- Infrared sensing technology integrated into the probe
- No sampling tubes or built-in fans required
- SPDT volt-free relay output
- Modbus RS485 RTU communication
- Adjustable smoke sensitivity using DIP switches
- Manual or automatic reset function
- Fast response time, typically 1–2 seconds
- Wide airflow velocity range: 0.03–25 m/s
- Compact enclosure for easy duct installation
- 250 mm sensing probe
- Duct mounting flange with integrated neoprene sealing gasket
- Suitable for HVAC and BMS applications
- CE compliant
Description
The TSD 250 is a compact true duct smoke detector designed for reliable smoke detection directly inside ventilation ducts.
Unlike conventional duct smoke detectors that use sampling tubes to draw air into an external detection chamber, the TSD 250 detects smoke directly in the airflow using an infrared sensing principle integrated into the sensing probe.
This direct detection principle eliminates the need for external sampling tubes or built-in fans, simplifying installation and reducing the number of components required.
The detector features adjustable smoke sensitivity, selectable manual or automatic reset and a volt-free SPDT relay output for integration with ventilation control systems, fire and smoke dampers and alarm systems.
Modbus RTU communication over RS485 enables integration with Building Management Systems (BMS), PLCs and HVAC controllers for remote relay status monitoring and control.
The TSD 250 operates at airflow velocities from 0.03 to 25 m/s and provides a typical response time of 1–2 seconds.
Its compact enclosure and 250 mm sensing probe make it suitable for commercial and industrial ventilation systems where direct duct smoke detection is required.
The duct mounting flange includes an integrated neoprene sealing gasket to improve sealing against the duct surface and reduce air leakage.
Applications
- Air handling units (AHU)
- Supply air ventilation ducts
- Return air ventilation ducts
- Commercial HVAC ventilation systems
- Industrial ventilation systems
- Ventilation systems crossing fire compartments
- Smoke detection for fan shutdown control
- Fire and smoke damper control
- Smoke extraction and ventilation shutdown systems
- Building Management Systems (BMS)
Technical Specifications
| Detection principle | Infrared smoke detection directly in the airflow |
| Detection method | Direct in-duct detection without sampling tubes |
| Sensitivity | Adjustable via internal DIP switches |
| Supply voltage | 24 Vac, 50–60 Hz / 24 Vdc |
| Power consumption | Approx. 1.5 VA at 24 Vdc |
| Relay output | SPDT volt-free contact |
| Relay contact rating | 5 A at 120 Vac / 24 Vdc |
| Digital communication | Modbus RTU over RS485 |
| Communication interface | RS485, 2-wire, half-duplex |
| Baud rate | 9600 bps |
| Communication format | 8 data bits, no parity, 1 stop bit |
| Modbus functions | Relay status monitoring and ON/OFF control |
| Modbus address range | 128–191 |
| Modbus address configuration | Internal DIP switches |
| Response time | Typically 1–2 seconds |
| Air velocity range | 0.03–25 m/s |
| Reset function | Manual or automatic, jumper selectable |
| Operating temperature | 0 to +50 °C |
| Operating humidity | 0–95% RH, non-condensing |
| Storage temperature | −20 to +60 °C |
| Protection class | IP64 |
| Enclosure material | ABS |
| Enclosure dimensions | 80 × 80 × 43 mm |
| Probe length | 250 mm |
| Probe diameter | Ø16.5 mm |
| Mounting flange diameter | Ø50 mm |
| Mounting flange gasket | Integrated neoprene sealing gasket |
| Cable entry | PG13.5 cable gland |
| Weight | Approx. 500 g |
| Compliance | CE compliant |
Ordering
TSD 250 – True Duct Smoke Detector
Download datasheet
Technical data sheet True Duct Smoke Detector TSD 250.pdf
Download CE declaration of conformity
CE declaration of conformity True Duct Smoke Detector, TSD 250.pdf
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