SENSOR MODULE
COVER
POWER BOARD
MODULE COVER
SENSOR HEAD
METAL
SAMPLING TUBE
POWER BOARD
EXHAUST TUBE
VARISTOR
4-WIRE
MAGNET TEST LOCATION
(sold seperately)
[3] generaL deScriPTion
Smoke introduced into an air duct system will be distributed throughout the
entire building. Smoke detectors designed for use in air duct systems are used
to sense the presence of smoke in the duct.
Model D4240 Duct Smoke Detectors utilize 4-wire photoelectric technology
for the detection of smoke. This detection method, when combined with an
efficient housing, samples air passing through the duct allowing detection of
a developing hazardous condition. When sufficient smoke is sensed, an alarm
signal is initiated and appropriate action can be taken to shut off fans, blow-
ers, change over air handling systems, etc. These actions can facilitate the
management of toxic smoke and fire gases throughout the areas served by the
duct system.
The D4240 detectors are designed to operate on 24 VDC/VAC or 240 VAC.
Alarm and supervisory relay contacts are available for control panel interface
(alarm initiation), HVAC control, and other auxiliary functions. Auxiliary re-
lays are provided for fan shut down. Detector interconnection provides signal-
ing of up to 50 other detectors in the loop for multiple fan shut down. These
detectors are not designed for 2-wire applications.
[3.1] deTecTor feaTure SeT
-Utilizes 2D51 plug-in head
-2 sensors to 1 power board capability
-Cover missing signal
-Sampling tubes install from front or rear of detector
-Compatible with existing accessories
[4] conTenTS of The ducT Smoke deTecTor kiT
1. Sensor/power board assembly and cover(s)
2. Three #10 sheet metal screws for mounting
3. Drilling template
4. One sampling tube end cap
5. One plastic exhaust tube
NOTE: A sampling tube must be ordered to complete the installation. It must
be the correct length for the width of the duct where it will be installed.
See Table 1 on page 3 to determine the inlet tube required for different duct
widths.
[5] deTecTor inSTaLLaTion
[5.1] VerifY air fLoW direcTion and VeLociTY
Model D4240 detectors are designed to be used in air handling systems with
air velocities of 100 to 4000 feet per minute. Duct widths from 6 inches to 12
feet can be accommodated. Be sure to check engineering specifications to
ensure that the air velocity in the duct falls within these parameters. If neces-
sary, use a velocity meter (anemometer) to check the air velocity in the duct.
[5.2] deTermine mounTing LocaTion and configuraTion
On ducts wider than 18 inches it is recommended that the detector be
mounted downstream of a bend, obstruction in the duct, or the supply or
return air inlet.
Exception:
Installation of duct detectors can be on or within a commercial
packaged rooftop heating and air-conditioning system, fire/smoke dampers
and economizers. They may be mounted in either the supply and/or return air
section as determined by local code.
Once a suitable location is selected, determine if the detector is to be mounted
in a side-by-side “rectangular” configuration or a top-over-bottom “square”
configuration as shown in
Figure 2
. If mounting in the square configuration,
remove the rear attachment screw, rotate the unit at the hinge, and replace the
screw into the new attachment hole as shown in
Figure 2
. Do NOT remove
the hinge screw during this process. Final installation approval shall be based
upon passing section 7.2.2 and/or 8.2.4 tests.
figure 2:
REMOVE SCREW AND PIVOT
DETECTOR AS SHOWN BELOW.
REPLACE SCREW
TO SECURE DETECTOR
IN PLACE.
H0550-00
[5.3] driLL The mounTing hoLeS
Remove the paper backing from the mounting template supplied. Affix the
template to the duct at the desired mounting location. Make sure the template
lies flat and smooth on the duct.
[5.3.1] for recTanguLar Side-bY-Side mounTing configuraTion:
Center punch at (4) target centers: (2) “A” for sampling tubes and (2) “B” for
the rectangular configuration mounting tabs as shown on mounting template.
Drill pilot holes at target “A” centers and cut two 1.375 inch diameter holes
using a 1
3
/
8
inch hole saw or punch. Drill .156 inch diameter holes using a
5
/
32
inch drill at target “B” centers.
[5.3.2] for Square ToP-oVer-boTTom mounTing
configuraTion or d4S SenSor comPonenT mounTing:
Center punch at (4) target centers: (2) “A” for sampling tubes and (2) “C” for
the square configuration mounting tabs as shown on mounting template. Drill
pilot holes at target “A” centers and cut two 1.375 inch diameter holes using
a 1
3
/
8
inch hole saw or punch. Drill .156 inch diameter holes using a
5
/
32
inch
drill at target “C” centers. If desired, drill an additional .156 inch hole at the
location of one of the mounting tabs on the lower housing.
[5.4] Secure The ducT deTecTor To The ducT
Use two (rectangular configuration) or three (square configuration) of the pro-
vided sheet metal screws to screw the duct detector to the duct.
CAUTION:
Do not overtighten the screws.
SS-300-022
2 I56-3936-002R
[2] figure 1. exPLoded VieW of ducT Smoke deTecTor comPonenTS:
H0549-03
