5
P/N 315-049708FA-4
punch (2) 1¼” (32mm) holes for input sampling and outlet
tubes, using the template as a guide. Clean all holes.
Sampling Tube Installation
The 8741, 8742 and 8743 duct smoke detectors use a
specially notched sampling tube, which may be ordered
separately in one of four standard lengths.
ST-10
For duct widths of 6" to 1.0’
ST-25
For duct widths of 1.0’ to 3.0’
ST-50
For duct widths of 3.0’ to 5.0’ (requires support)
ST-100*
For duct widths of 5.0’ to 10.0’ (requires support)
*
This model is supplied as two 5 ft. sections with a coupling.
Assembly is required for installation.
Each model is manufactured with a different number and
size of sampling holes. Only the specific tube must be used
for the specified duct width.
Standard sampling tubes are steel tubes with air intake holes
drilled the entire length of the tube. These tubes can be cut
to length and must span at least 80% the width of the duct.
Sampling tubes over 3.0’ must be supported on the opposite
side of the duct. To ensure the correct operation, the red
stopper (stopper in installation kit) must be inserted in the
end of the air input sampling tube. If the input tube protrudes
through the opposite side of the duct, the opening around
the tube must be sealed. For custom duct widths, always
use the next longest standard size and cut down to the exact
requirement.
Once the airflow direction has been determined (refer to Figure
3), insert the input and outlet tubes into the duct housing.
INPUT TUBE HOLES
FACE AIR FLOW
INSERT RED STOPPER
THIS END OF INPUT TUBE
OUTLET TUBE INSTALLED
DOWNSTREAM OF AIRFLOW
DO NOT INSERT RED STOPPER
AIR FLOW DIRECTION
DUCT WIDTH
TUBE SUPPORT ONLY FOR DUCTS GREATER THAN 3 FEET WIDE
NOTE: Mountings shown
are typical. Detectors can
be installed side, bottom
or top of duct as long as
proper tube operation and
flow/pressure performance
is maintained.
Figure 3
Sampling Tube Orientation
