2.
For tubes longer than the width of the air duct, the tube should extend
out of the opposite side of the duct. Drill a 1.9 cm hole in the duct op-
posite the hole already cut for the sampling tube. Ensure that the sam-
pling tube is angled downward from the duct smoke detector to allow
for moisture drainage away from the detector. The sampling tube should
be angled at least .63 cm downward for every 30.5 cm of duct width
per Figure 4. There should be 10 to 12 holes spaced as evenly as pos-
sible across the width of the duct. If there are more than 2 holes in the
section of the tube extending out of the duct, select a shorter tube using
Table 1. Otherwise, trim the tube to leave approximately 2.54-5.08cm
extending outside the duct. Plug the end with the end cap and tape
closed any holes in the protruding section of the tube. Be sure to seal the
duct where the tube protrudes.
figURe 4:
DETECT O R
1.9 cm
HOLE
30.5 cm
.63 cm
.5 cm
H0215-01
NOTE: Air currents inside the duct may cause excessive vibration, especially
when the longer sampling tubes are used. In these cases, a 7.6 cm floor flange
(available at most plumbing supply stores) may be used to fasten the sam-
pling tube to the other side of the duct. When using the flange/connector
mounting technique, drill a 2.5 to 3.2 cm hole where the flange will be used.
[6.3] MoDificationS of SaMpLing tUBeS
There may be applications where duct widths are not what is specified for the
installation. In such cases, it is permissible to modify a sampling tube that is
longer than necessary to span the duct width.
Use a 4.9 mm drill and add the appropriate number of holes so that the total
number of holes exposed to the air flow in the duct is 10 to 12. Space the ad-
ditional holes as evenly as possible over the length of the tube.
NOTE: This procedure should only be used as a temporary fix. It is not in-
tended as a permanent substitute for ordering the correct length tubes.
[6.4] ReMote SaMpLing tUBe inStaLLation
The detector arrangement can also incorporate the remote mounting of the
sampling tube and/or exhaust tube. In this case both the detector, sampling
tube and exhaust tube (if included) should be rigidly mounted to withstand
the pressure and vibrations caused by the air velocity. The location of the
detector’s sampling tube should be such that there is uniform airflow in the
cross section area.
The pressure differential across the sampling and exhaust ports in the detec-
tor housing shall be verified to be between .25 and 28.2 mm of water. Do so
by measuring the pressure difference between the inlet and outlet ports on
the detector housing using a manometer as described in Section 10.4.4 of this
manual.
[7] MeaSUReMent teStS
[7.1] aiR fLow
The D2E is designed to operate over an extended air speed range of 1.5 to 20.3
m/sec. To verify sufficient sampling of ducted air, turn the air handler on and
use a manometer to measure the differential pressure between the two sam-
pling tubes. The differential pressure should measure at least .25 mm of water
and no more than 28.2 mm of water. Because most commercially available
manometers cannot accurately measure very low pressure differentials, ap-
plications with less than 2.54 m/sec of duct air speed may require one of the
following: 1) the use of a current-sourcing pressure transmitter (per Section
7.2; or 2) the use of aerosol smoke per section 10.4.4.
[6] SaMpLing tUBe inStaLLation
[6.1] SaMpLing tUBe SeLection
The sampling tube must be purchased separately. Order the correct length,
as specified in Table 1, for width of the duct where it will be installed. It is
recommended that the sampling tube length extend at least
2
/
3
across the duct
width for optimal performance.
taBLe 1. SaMpLing tUBeS RecoMMenDeD foR
DiffeRent DUct wiDthS:
Outside Duct Width
Sampling Tube
Recommended*
Up to 30.5 cm
DST1
30.5 to61 cm
DST1.5
61 to 122 cm
DST3
122 to 244 cm
DST5
244 to 366 cm
DST10 (2-piece)
*Must extend a minimum of
2
/
3
the duct width
The sampling tube is always installed with the air inlet holes facing into the
air flow. To assist proper installation, the tube’s connector is marked with an
arrow. Make sure the sampling tube is mounted so that the arrow points into
the airflow as shown in Figure 3. 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 3. The sampling tube and exhaust tube
can be mounted in either housing connection as long as the exhaust tube is
mounted downstream from the sampling tube.
figURe 3. aiR DUct DetectoR SaMpLing tUBe:
SAMPLING TUBE ENDCAP
ARROW MUST FACE
INTO AIR FLOW
AIR FLOW
DIRECTION
H0551-00
CAUTION: The sampling tube end cap, included with the detector, is criti-
cal to proper operation of the duct smoke detector. The end cap is needed to
create the proper air flow to the sensor of the duct smoke detector. Once any
sampling tube length adjustments are made, plug the end of the sampling tube
with the provided end cap.
A plastic exhaust tube is included with the unit to be installed if needed. In-
stall into the housing connection that is downstream from the sampling tube
connection. The exhaust tube can be installed from the front of the detector
or the back. A longer 30.5 cm exhaust tube, model ETX is available as an ac-
cessory in cases where the molded exhaust tube does not extend at least 5 cm
into the duct.
[6.2] SaMpLing tUBe inStaLLation
1.
For tubes shorter than the width of the duct, slide the sampling tube,
with installed end cap, into the housing connection that meets the air-
flow first. Position the tube so that the arrow points into the airflow as
shown in Figure 3. Sampling tubes over 91.4 cm long should be sup-
ported at the end opposite of the duct detector. In ducts wider than
244cm, work must be performed inside the duct to couple the other sec-
tion of the sampling tube to the section already installed using the 4 cm
conduit fitting supplied. Make sure that the holes on both sections of the
air inlet sampling tube are lined up and facing into the airflow.
SS-300-020
3
I56-3536-003R
