System Sensor DH100ACDCLWP - Manual (Page 3)

[5.5.1] Installation For Ducts Greater Than 1 1 ⁄
2
Feet
But Less Than 8 Feet Wide
1. If the tube is longer than the width of the air duct, drill a 3 ⁄
4
˝
hole in the duct opposite the hole already cut for the sam-
pling tube. Make sure the hole is 1˝ to 2˝ below the inlet 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. 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.
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. Oth-
erwise, trim the end of the tube protruding through the duct
so that 1˝ to 2˝ of the tube extend outside the duct. Plug this
end with the end cap and tape closed any holes in the pro-
truding 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 detector. The end cap is needed to create the proper air
flow to the sensor of the duct smoke detector.
Figure 3. Air duct detector sampling tube:
SAMPLING
TUBE
END CAP
AIR HOLES
ARROW
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
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
H0109-01
NOTE: Only metal sampling tubes may be used on orientations
C and D.
[5.5.2] Installation For Ducts More Than 8 Feet Wide
NOTE: To install sampling tubes in ducts more than 8 feet wide,
work must be performed inside the air duct. Sampling of air in
ducts wider than 8 feet is accomplished by using the ST-10 sam-
pling tube. 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
and support the end opposite the duct smoke detector.
Install the inlet tube as follows:
1. Drill a
3 ⁄
4
˝ hole in the duct directly opposite the hole already
drilled for the inlet tube. Make sure the hole is 1 to 2˝ below
the inlet hole on the opposite side of the duct to allow for
moisture drainage.
2. Slide the sampling tube with the flange into the housing bush-
ing that meets the air flow first. Position the tube so that the
arrow points into the air flow. Secure the tube flange to the
housing bushing with two #6 self-tapping screws.
3. From inside the duct, couple the other sections of the sam-
pling tube to the section already installed using the 1 ⁄
2
˝ con-
duit fittings supplied. Make sure that the holes on both of the
air inlet tubes are lined up and facing into the air flow.
4. Trim the end of the tube protruding through the duct so that
1 to 2˝ of the tube extend outside the duct. Plug this end
with the end cap and tape closed any holes in the protrud-
ing section of the tube. Be sure to seal the duct when the
tube protrudes.
NOTE: An alternate method to using the ST-10 is to use two ST-5
sampling tubes. Remove the flange from one of the tubes and in-
stall as described above. After the installation, use electrical tape
to close off some of the sampling holes so that there are a total
of 10 to 12 holes spaced as evenly as possible across the width of
the duct.
NOTE: Air currents inside the duct may cause excessive vibration,
especially when the longer sampling tubes are used. In these cases
a 3 inch floor flange (available at most plumbing supply stores)
may be used to fasten the sampling tube to the other side of the
duct. When using the flange/connector mounting technique, drill
a 1-inch to 1
1 ⁄
4
˝ hole where the flange will be used.
[5.5.3] Modifications of Sampling Tubes
There may be applications where duct widths are not what is
specified for the installation. In such cases, it is permissible to
modify a sampling tube that is longer than necessary to span the
duct width.
Use a 0.193-inch diameter (#11) drill and add the appropriate num-
ber of holes so that the total number of holes exposed to the air
flow in the duct is 10 to 12. Space the additional holes as evenly as
possible over the length of the tube.
NOTE: This procedure should only be used as a temporary fix. It
is not intended as a permanent substitute for ordering the correct
length tubes.
[5.5.4] Alternate Method of Sampling Tube Installation
The detector arrangement can also incorporate the remote mount-
ing of the sampling tube and/or exhaust tube. In this case both
the detector, sampling tube and exhaust tube (if included) should
be rigidly mounted to withstand the pressure and resonant vibra-
tions caused by the air velocity. The location of the detector’s
sampling tube should be such that there is uniform airflow in the
cross section area.
An air tight connection shall be made between the sampling tube,
exhaust tube and their corresponding ports on the detector hous-
ing. Upon selection of location in the system, pressure differential
across the sampling and exhaust ports in the detector housing
shall be verified to be within the allowable range of the detec-
tor. This is accomplished by measuring the pressure difference
between the inlet and outlet ports on the detector housing using a
manometer as described in Section 6 of this manual.
D200-24-00 3 I56-0056-009R