[3] Secure The Detector Housing To The Duct
Slide the foam gaskets over the tube bushings as shown in Figure 3. Use the two 1
1
⁄
4
˝ long sheet metal screws to screw the detector
housing to the duct.
CAUTION:
Do not overtighten the screws.
Figure 3. Installation of foam gaskets
over sampling tube bushings:
SCREW HOLES FOR
ATTACHING HOUSING
TO DUCT WORK.
[4] Sampling Tube Installation for Ducts Greater Than 1
1
⁄
2
Feet (0.46m) Wide
The sampling tube is identified by a series of air inlet holes on the tube. A plastic tube is included for ducts up to 1
1
⁄
2
feet (0.46m)
wide. All other lengths must be purchased separately. Order the correct length, as specified in Table 1, for width of the duct where it
will be installed. It is recommended that the sampling tube length extend at least
2
/
3
across the duct width for optimal performance.
The exhaust tube is molded onto the base of the duct housing, and the A2440-00 Exhaust Tube Extension is available as an accessory
in those cases where the molded exhaust port does not extend at least 2 inches (50mm) into the duct.
The sampling tube is always installed with the air inlet holes
facing into the air flow. To assist proper installation, the tube’s
mounting flange is marked with an arrow. Make sure the sam-
pling tube is mounted so that the arrow points into the air flow
(see Figure 4). Figure 5 shows the various combinations of tube
mounting configurations with respect to air flow. Mounting the
detector housing in a vertical orientation is acceptable, provided
that a metal sampling tube is used and the air flows directly into
the sampling tube holes as indicated in Figure 4.
[4.1] Installation For Ducts Greater Than 1
1
⁄
2
Feet
(0.46m) But Less Than 8 Feet (2.4m) Wide
1. If the tube is longer than the width of the air duct, drill a
3
⁄
4
˝
(19mm) hole in the duct opposite the hole already cut for the
sampling tube. Make sure the hole is 1˝ to 2˝ (25 to 50mm)
below the sampling hole on the opposite side of the duct to
allow moisture drainage away from the detector. If the tube is
shorter than the width of the air duct, install the end cap into
the sampling tube as shown in Figure 4. Sampling tubes over
3 ft. (0.91m) long must be supported at the end opposite the
duct smoke detector.
2. Slide the tube into the housing bushing that meets the air flow
first. Position the tube so that the arrow points into the air
flow, as shown in Figure 4.
3. Secure the tube flange to the housing bushing with two #6 self-
tapping screws.
4. For tubes longer than the width of the air duct, the tube
should extend out of the opposite side of the duct. If there are
more than 2 holes in the section of the tube extending out of
the duct, select a different length using Table 1. Otherwise,
trim the end of the tube protruding through the duct so that 1˝
to 2˝ (25 to 50mm) of the tube extend outside the duct. Plug
this end with the end cap and tape closed any holes in the
protruding section of the tube. Be sure to seal the duct where
the tube protrudes.
NOTE:
The sampling tube end cap is critical to the proper opera-
tion of the duct smoke detectors. The end cap is needed to create
the proper air flow to the sensor of the duct smoke detector.
F300-28-00
3
I56-1974-006R
*Must extend a minimum of
2
⁄
3
the duct width
H0107-00
Outside Duct Width
Sampling Tube Recommended*
1 to 2 ft. (0.3 to 0.6 m)
ST-1.5
2 to 4 ft. (0.6 to 1.2 m)
ST-3
4 to 8 ft. (1.2 to 2.4 m)
ST-5
8 to 12 ft. (2.4 to 3.7 m)
ST-10
Table 1. Sampling tubes recommended for different
Duct Widths:
H0108-02
Figure 5. Tube mounting configurations with varying
air flow direction:
AIR FLOW
DIRECTION
DETECTOR
HOUSING
DOTS INDICATE POSITION OF SAMPLING TUBE HOLES
AIR FLOW
DIRECTION
DETECTOR
HOUSING
SAMPLING
TUBE
EXHAUST
TUBE
AIR FLOW
DIRECTION
EXHAUST
TUBE
SAMPLING
TUBE
SAMPLING
TUBE
EXHAUST
TUBE
DETECTOR
HOUSING
AIR FLOW
DIRECTION
DETECTOR
HOUSING
A.
B.
C.
D.
HORIZONTAL MOUNTING OF HOUSING
VERTICAL MOUNTING OF HOUSING
NOTE: ONLY METAL SAMPLING TUBES CAN BE INSTALLED IN ORIENTATIONS C AND D.
NOTE:
Only metal sampling tubes can be installed
in orientations C and D.
H0109-01
SAMPLING
TUBE
END CAP
AIR HOLES
ARROW
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
Figure 4. Air duct detector sampling tube: