Intelligent Products—DH500 Series Intelligent Air Duct Smoke Detector 15
!
CAUTION: Equipment damage hazard. In no case should
more than two air inlet holes be cut off the tube.
There must be a minimum of ten holes in the tube
exposed to the air stream.
Installation for Ducts more than Eight Feet Wide
To install inlet tubes in ducts more than eight feet wide, work must be
performed inside the air duct. Sampling of air in ducts wider than
eight feet is accomplished by using the ST-10 inlet sampling tube.
1.
Drill a 3/4 inch hole in the duct directly opposite the hole already
drilled for the inlet tube.
2.
Slide the inlet tube into the bushing located in the center of the duct
housing.
3.
Position the tube so that the arrows point into the air flow.
4.
Secure the tube flange to the housing bushing with the two No. 6
self-tapping screws.
5.
From inside the duct, couple the other section of the inlet tube to the
section already installed using the 1/2 inch conduit fitting supplied.
Make sure that the holes on both of the air inlet tubes are lined up
facing the direction of air flow.
6.
Trim the end of the tube protruding through the duct so that one to
two inches of the tube extends outside the duct.
7.
Plug this end with the tube end plug, and tape close any holes in the
protruding section of the tube.
8.
Be sure to seal the duct when the tube protrudes.
9.
Ensure that any tube over three feet long that does not protrude
through the duct on the side opposite the housing is supported by
other means.
For an alternate method of using the ST-10:
1.
Use two ST-5 inlet tubes.
2.
Remove the flange from one of the tubes and install as described in
the Installation for Ducts more than Eight Feet Wide section of this
technical bulletin.
3.
After the installation, use electrician’s tape to close off some of the
sampling holes so that there is a total of 12 holes spaced as evenly as
possible across the width of the duct.
Air currents inside the duct may cause excessive vibration. This vibration
can slowly open the seal around the tube and permit air to escape.