System Sensor DH500ACDC - Manual (Page 3)

D500-07-00 3 I56-432-11R
Exception: Where it is physically impossible to locate the
detector accordingly, the detector can be positioned closer
than six duct widths, but as far as possible from the open-
ing, bend, or deflection plates.
Step 3. Mount Duct Housing
Remove the duct housing cover. Slide the foam gaskets over
the tube bushings as shown in Figure 2A. Make sure the
two small holes in the gaskets line up with the two duct
housing mounting holes. Put one 5/16-inch O-ring over
each of the two #10 sheet metal screws. Use the two sheet
metal screws to secure the duct housing to the duct.
Table 1. Sampling (Inlet) Tubes
TUBE
OUTSIDE DUCT WIDTH
ST-1.5 1 to 2 ft. (0.3 to 0.6 m)
ST-3 2 to 4 ft. (0.6 to 1.2 m)
ST-5 4 to 8 ft. (1.2 to 2.4 m)
ST-10 8 to 12 ft. (2.4 to 3.7 m)
A78-2046-00
HOLE B
HOLE A
DUCT
WALL
SPEED
NUT
Figure 2. Speed nut mounting location:
CAUTION: Do not overtighten the screws.
Figure 2A. Installation of foam gaskets over sam-
pling 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
A78-2449-00
INLET
TUBE
END
PLUG
AIR HOLES
ARROWS
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
Step 4. Install The Inlet Tube
The inlet tube (shown in Figure 3) 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 the width of the duct where it will be installed. The
exhaust tube is molded into the base of the duct housing.
The inlet tube should be installed in the inlet sampling tube
bushing located in the center of the duct detector housing.
(See Figure 2A.) The air inlet holes must face into the air
flow. To assure proper installation, the tube mounting
flange is marked with arrows. Mount the inlet tube so that
the arrows point into the air flow. Figure 4 shows the vari-
ous combinations of duct detector and tube mounting con-
figurations with respect to air flow.
Figure 3. Air duct detector inlet sampling tube:
A78-2047-00