System Sensor DH400P - Manual (Page 3)

[5.2] 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. Center punch holes A and B. Drill the
holes as indicated on the template. Slide the two speed nuts
over the two small holes (hole A) next to the sampling tube
bushing holes (hole B) previously drilled in the duct. (See
Figure 3.)
[5.3] Secure The Detector Housing To The Duct
Remove the duct housing cover. Slide the foam gaskets over
the tube bushings as shown in Figure 2. Make sure the two
small holes in the gaskets line up with the two base mount-
ing holes. Put one 5/16-inch O-ring over each of the two
#10 sheet metal screws. Use the two sheet metal screws to
screw the detector housing to the duct. CAUTION: Do not
overtighten the screws.
Figure 2. Installation of foam gaskets over sampling
tube bushings:
SCREW HOLES FOR ATTACHING
DETECTOR HOUSING TO DUCT
FOAM GASKETS
EXHAUST TUBE
(EXTENSION BUSHING)
DUCT DETECTOR
HOUSING
O-RINGS
MOUNTING
SCREWS
INLET SAMPLING
TUBE BUSHING
A78-2045-00
Figure 3. Speed nut mounting location:
HOLE B
HOLE A
DUCT
WALL
SPEED
NUT
A78-2046-00
[5.4] Install The Inlet
The inlet tube (shown in Figure 4) is identified by a series
of air inlet holes on the tube. This tube must be purchased
separately. Order the correct length, as specified in Table 1,
for width of the duct where it will be installed. The exhaust
tube is molded onto the base of the duct housing, and the
A2440-00 Exhaust Tube Extension is available as an acces-
sory in those cases where the molded exhaust port does not
extend at least 2 inches into the duct.
The inlet tube is always installed in the centermost housing
bushing, with the air inlet holes facing into the air flow. To
assist proper installation, the tube’s mounting flange is
marked with arrows. Make sure the inlet tube is mounted
so that the arrows point into the air flow. Figure 5 shows
the various combinations of tube mounting configurations
with respect to air flow. Mounting the detector housing in a
vertical orientation is acceptable, provided that the air
flows directly into the sampling tube holes as indicated in
Figure 4.
Table 1. Inlet tubes required for different duct
widths:
Outside Duct Width Inlet Tube Required
1 to 2 ft. ST-1.5
2 to 4 ft. ST-3
4 to 8 ft. ST-5
8 to 12 ft. ST-10
D400-14-00 3 I56-554-05