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LOCATION PREREQUISITES
This guideline contains general information on duct smoke
detector installation, but does not preclude the NFPA and/or
ICC documents listed. Air Products and Controls assumes no
responsibility for improperly installed duct detectors. To determine
the correct installation position for an SL-2000 Series duct smoke
detector, the following factors must be considered.
1) A uniform non-turbulent (laminar) air flow between 100
ft/min. to 4,000 ft/min. must be present in the HVAC duct. To
determine duct velocities, examine the engineering specifica-
tions that define the expected velocities or use an Alnor model
6000AP velocity meter (or equivalent).
2) To minimize the impact of air turbulence and stratification on
performance, a duct smoke detector should be located as far as
possible downstream from any obstruction (i.e. deflector plates,
elbows, dampers, etc.). In all situations, confirmation of veloci-
ty and pressure differential within specifications is required.
The pressure differential between the input sampling (high
pressure) tube and exhaust (low pressure) tube for the SL-2000
Series smoke duct detector should be greater than 0.01 inches
of water and less than 1.2 inches of water.
3) Identify a code compliant location (supply or return side, or
both) for the installation of the duct unit that will permit easy
access for viewing and serviceability.
4) When installing on the return side, install duct units prior to the
air being exhausted from the building or diluted with outside
“fresh” air.
5) When installing duct smoke units downstream of filters, fires
occurring in the filters will be detected, but if the filters become
blocked, insufficient air flow through the duct unit will prevent
the correct operation of the duct detector. Duct units installed in
the supply air side may monitor upstream equipment and/or
filters.
6) Where possible, install duct detectors upstream of air humidi-
fiers and downstream of dehumidifiers.
7) To prevent false alarms, the duct detector should not be mount-
ed in areas of extreme high or low temperatures, in areas where
high humidity exists, or in areas where the duct may
contain gases or excessive dust.
SAMPLING TUBE ASSEMBLY
The SL-2000 Series duct smoke detectors employ a specially
notched sampling tube, which may be ordered separately in one of
four standard lengths.
STN-1.0 For duct widths of 6” TO 1.0’
STN-2.5 For duct widths of 1.0’ TO 3.0’
STN-5.0 For duct widths of 3.0’ TO 5.0’
STN-10.0 For duct widths of 5.0’ TO 10.0’
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 of the sensing tube, the red end
cap (red stopper in installation kit) must be inserted in the end of
the air intake sampling tube. For custom duct widths, always use
the next longest standard size and cut down to the exact require-
ment.
MECHANICAL INSTALLATION
“NO-TOOLS” TUBE INSTALLATION
The SL-2000 Series duct smoke detector provides a unique,
atent-pending mechanism for installation and/or removal of the
sampling and exhaust tubes from either the front or rear of the
detector housing.
Once the air flow direction has been determined, insert the inlet
and exhaust tubes into the duct smoke detector. If the cover is in
place, the tubes may be inserted into the back of the detector via
the key-slots provided. Simply push the tube into place against the
spring loaded retainer, and turn into the correct position, allowing
the key to “lock” the tube in the desired orientation. For front side
installation, simply rotate the tube retainer until the tube may be
inserted and oriented properly. Once the tube is installed, rotate
the retainer back into place to lock down the tube. Ensure air
intake sampling tube is positioned so that the inlet holes are
directly facing the air flow.
DUCT PREPARATION
Remove mounting template from the installation kit. Remove
paper backing from the mounting template and affix it to the duct
at the desired location. Using the template as a guide, drill (2)
mounting holes, 3/32” (2.5mm) for the #12 x ½” sheet metal
screws packaged in the installation kit. Drill or punch (2) 1¼”
(32mm) holes for inlet sampling and exhaust tubes, using the
template as a guide. Clean all holes.
MOUNTING
After securing the sampling and exhaust tubes to the duct smoke
unit, (or initially placing the tubes through the 1¼” holes drilled or
punched in the HVAC duct to accept the inlet sampling and
exhaust tubes and then attaching them to the duct unit), hold the
duct unit assembly in position and use (2) # 12 x ½” sheet metal
screws (packaged in the installation kit) to secure the duct smoke
detector to the HVAC duct sheet metal.
AIR SAMPLING VERIFICATION
To ensure correct operation of the duct unit use a Magnehelic
differential pressure gauge, Dwyer 2000 or 4000 Series (or equiv-
alent) to determine the differential pressure between the inlet (high
side) and exhaust (low side) tubes. The differential pressure
between the two tubes should be greater than 0.01 inches of water
and less than 1.2 inches of water.
NOTE: Mountings shown
are typical. Detectors can
be installed side, bottom or
top of ducts as long as
proper tube operation and
flow/pressure performance
is maintained.
DUCT WIDTH
EXHAUST TUBE INSTALLED
DOWNSTREAM OF AIR
FLOW. DO NOT INSERT
RED STOPPER.
INSERT RED STOPPER
THIS END OF INLET TUBE.
INLET TUBE HOLES
FACE AIR FLOW.
Tube Support Hole only for Ducts Greater than 3 Feet Wide