WARNING
In no case should more than 2 air inlet holes be cut off the
tube. There must be a minimum of 10 holes in the tube ex-
posed to the air stream.
[5.4.2] Installation For Ducts More Than 8 Feet Wide
NOTE:
To install inlet 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 inlet sampling tube. If the tube is
shorter than the width of the air duct, install the end
plug into the inlet tube as shown in Figure 4 and sup-
port the end opposite the duct smoke detector.
Install the inlet tube as follows:
1. Drill a
3
/
4
-inch hole in the duct opposite the hole already
drilled for the inlet tube. Drill the hole 1
″
to 2
″
below the
inlet hole on the opposite side of the duct to allow for
moisture drainage away from the detector.
2. Slide the inlet tube with the flange into the housing bush-
ing that meets the air flow first. Position the tube so that
the arrows point 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 in-
let tube to the section already installed using the
1
/
2
-inch
conduit 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 plug and tape closed any holes in
the protruding 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 inlet tubes. Remove the flange from one
of the tubes and install 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
″
to 1
1
/
4
″
inch hole
where the flange will be used.
[5.4.3] Modifications of Inlet Sampling Tubes
There may be applications where duct widths are not what
is specified for the installation. In such cases, it is permis-
sible to modify an inlet sampling tube that is longer than
necessary to span the duct width.
Use a 0.193-inch diameter (#11) drill and add the appropriate
number 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] Install The Filters
To install the sampling tube filters, simply push the filters
into the sampling and exhaust tube holes as shown in Fig-
ure 6. If a metal sampling tube is used, install the filter over
the sampling tube.
Figure 6. Sampling tube filter installation:
A78-2106-01
CAUTION
Filters require periodic cleaning or replacement, depending
on the amount of dust and dirt accumulated. Visually in-
spect the filters at least quarterly; inspect them more often
if the dust accumulation warrants it. See Section [6] for
more information. Replacement filters can be ordered from
System Sensor, 3825 Ohio Ave., St. Charles, IL 60174. (Ex-
haust tube/intake tube filter P/N F36-09-00)
[5.6] Field Wiring
Wiring Installation Guidelines
All wiring must be installed in compliance with the Na-
tional Electrical Code and the local codes having jurisdic-
tion. Proper wire gauges should be used. The conductors
used to connect smoke detectors to control panels and ac-
cessory devices should be color-coded to prevent wiring
mistakes. Improper connections can prevent a system from
responding properly in the event of a fire.
D100-67-00
4
I56-1148-04
