[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 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 sampling 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 50 mm) 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 operation of
the duct smoke detectors. The end cap is needed to create the
proper air flow to the sensor of the duct smoke detector.
F300-27-00
3
I56-1975-004R
SCREW HOLES FOR
ATTACHING HOUSING
TO DUCT WORK.
Figure 3. Installation of foam gaskets over sampling
tube bushings:
Figure 5. Tube mounting configurations with varying
air flow direction:
Table 1. Sampling tubes recommended for different
duct widths:
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
*Must extend a minimum of
2
⁄
3
the duct width.
SAMPLING
TUBE
END CAP
AIR HOLES
ARROW
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
Figure 4. Air duct detector sampling tube:
H0108-02
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.
H0107-00
H0109-01
