System Sensor DH400P - Manual (Page 4)

[5.4.1] Installation For Ducts Less Than 8 Feet Wide
1. If the tube is longer than the width of the air duct, drill a
3/4-inch hole in the duct directly opposite the hole al-
ready cut for the inlet 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. Sampling tubes over 3 ft. long
must be supported at the end opposite the duct detector.
2. Slide the tube into the centermost housing bushing. Po-
sition the tube so that the arrows point into the air flow.
3. Secure the tube flange to the housing bushing with two
#6 self-tapping screws.
4. For tubes longer than the width of the air duct, the tube
should extend out of the opposite side of the duct. If
there are more than 2 holes in the section of the tube ex-
tending out of the duct, select a different length using
Table 1. Otherwise, trim the end of the tube protruding
through the duct so that 1 to 2 inches of the tube extend
outside the duct. Plug this end with the end plug and
INLET
TUBE
END
PLUG
AIR HOLES
ARROWS
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
Figure 4. Air duct detector inlet sampling tube:
A78-2047-00
Figure 5. Tube mounting configurations with varying
air flow direction:
A78-1812-01
AIR FLOW
DIRECTION
DUCT
DETECTOR
HOUSING
DOTS INDICATE POSITION OF
SAMPLING TUBE HOLES
AIR FLOW
DIRECTION
DUCT
DETECTOR
HOUSING
INLET
TUBE
EXHAUST
TUBE
AIR FLOW
DIRECTION
INLET
TUBE
EXHAUST
TUBE
INLET
TUBE
EXHAUST
TUBE
DUCT
DETECTOR
HOUSING
AIR FLOW
DIRECTION
EXHAUST
TUBE
INLET
TUBE
DUCT
DETECTOR
HOUSING
tape closed any holes in the protruding section of the
tube. Be sure to seal the duct when the tube protrudes.
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 accom-
plished 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 support the end opposite the duct de-
tector.
D400-14-00 4 I56-554-05