System Sensor DST3 InnovairFlex Sampling Tube
Overview
The System Sensor DST3 is a patented sampling tube component engineered for the InnovairFlex duct smoke detection line. It mounts directly into 2 to 4 foot ductwork runs and pulls air samples back to the detector head via gravity and negative pressure — the core mechanism that lets a single detector monitor extended duct segments without multiple sensor heads. The DST3 operates at 29VDC and integrates with System Sensor's 4-wire photoelectric duct detectors (including the D4120). This is the right choice when your HVAC design requires sampling points distributed across rectangular or square ductwork and you want to avoid the cost and complexity of multiple independent detectors.
Compatibility
The DST3 is designed specifically for System Sensor InnovairFlex series duct smoke detectors, including the D4120 4-wire photoelectric model. The patented sampling tube installs from the front or back of the detector housing — no tools required — and works with both square and rectangular ductwork configurations. It supports air velocity ratings from 100 ft/min to 4,000 ft/min, making it suitable for standard commercial HVAC systems operating in that range. If your detector operates outside this velocity range or uses a different manufacturer's duct detection system, this tube will not function correctly.
Installation Notes
The DST3 connects via a ¾-inch conduit knockout on the detector housing. The InnovairFlex detector itself provides ample wiring space and includes built-in short circuit protection. Mounting orientation (front or back installation) depends on your ductwork layout — verify clear air passage through the full 2 to 4 foot tube length before final installation. Operating temperature range is –4°F to 158°F with humidity tolerance of 0 to 95 percent non-condensing. Do not install in condensing environments or where freezing water accumulation is possible.
