35
Dirty Sensor Test Using an SD-TRK4
1. Turn the key switch to the RESET/TEST position for two 
seconds.
2. Verify that the test/reset station’s Trouble LED flashes.
Detector Cleaning
CLEANING THE SMOKE DETECTOR
Clean the duct smoke sensor when the Dirty LED is flashing con-
tinuously or sooner, if conditions warrant. 
1. Disconnect power from the duct detector then remove the 
sensor’s cover. See Fig. 49.
2. Using a vacuum cleaner, clean compressed air, or a soft 
bristle brush, remove loose dirt and debris from inside the 
sensor housing and cover. Use isopropyl alcohol and a 
lint-free cloth to remove dirt and other contaminants from 
the gasket on the sensor’s cover.
Fig. 49 — Sensor Cleaning Diagram
3. Squeeze the retainer clips on both sides of the optic housing.
4. Lift the housing away from the printed circuit board.
5. Gently remove dirt and debris from around the optic plate 
and inside the optic housing.
6. Replace the optic housing and sensor cover.
7. Connect power to the duct detector then perform a sensor 
alarm test.
Indicators
NORMAL STATE
The smoke detector operates in the normal state in the absence of 
any trouble conditions and when its sensing chamber is free of 
smoke. In the normal state, the Power LED on both the sensor and 
the controller are on and all other LEDs are off.
ALARM STATE
The smoke detector enters the alarm state when the amount of 
smoke particulate in the sensor’s sensing chamber exceeds the 
alarm threshold value. (See Table 4.) Upon entering the alarm 
state:
• The sensor’s Alarm LED and the controller’s Alarm LED 
turn on.
• The contacts on the controller’s two auxiliary relays switch 
positions.
• The contacts on the controller’s alarm initiation relay close.
• The controller’s remote alarm LED output is activated 
(turned on).
• The controller’s high impedance multiple fan shutdown 
control line is pulled to ground Trouble state.
The SuperDuct™ duct smoke detector enters the trouble state un-
der the following conditions:
• A sensor’s cover is removed and 20 minutes pass before it 
is properly secured.
• A sensor’s environmental compensation limit is reached 
(100% dirty).
• A wiring fault between a sensor and the controller is detected.
An internal sensor fault is detected upon entering the trouble state:
• The contacts on the controller’s supervisory relay switch 
positions. (See Fig. 
50.)
• If a sensor trouble, the sensor’s Trouble LED the control-
ler’s Trouble LED turn on.
• If 100% dirty, the sensor’s Dirty LED turns on and the 
controller’s Trouble LED flashes continuously.
• If a wiring fault between a sensor and the controller, the 
controller’s Trouble LED turns on but not the sensor’s.
 
Fig. 50 — Controller Assembly
NOTE: All troubles are latched by the duct smoke detector. The 
trouble condition must be cleared and then the duct smoke detec-
tor must be reset in order to restore it to the normal state.
IMPORTANT: Failure to follow this ALERT can result in 
an unnecessary evacuation of the facility.
Holding the test magnet to the target area for longer than seven 
seconds will put the detector into the alarm state and activate 
all automatic alarm responses.
IMPORTANT: OPERATIONAL TEST ALERT
Failure to follow this ALERT can result in an unnecessary 
evacuation of the facility.
If the smoke detector is connected to a fire alarm system, first 
notify the proper authorities that the detector is undergoing 
maintenance then disable the relevant circuit to avoid 
generating a false alarm.
HVAC Duct
Sampling 
Tube
Retainer
Clip
Optic
Plate
Optic
Housing
Sensor
Housing
Airflow
Table 4 — Detector Indicators
CONTROL OR 
INDICATOR
 DESCRIPTION
Magnetic test/
reset switch
Resets the sensor when it is in the alarm or trouble 
state. Activates or tests the sensor when it is in the 
normal state.
Alarm LED  Indicates the sensor is in the alarm state.
Trouble LED  Indicates the sensor is in the trouble state.
Dirty LED 
Indicates the amount of environmental 
compensation used by the sensor (flashing 
continuously = 100%)
Power LED  Indicates the sensor is energized.
Alarm
Power
Test/Reset
Switch
Trouble
RESET
ALARM
TROUBLE
POWER