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b. Affix the adhesive backed template (5) to the side of the ductwork.
c. Drill the four 0.110 diameter holes with a No. 35 drill bit and cut or punch out two 7/8-inch
diameter holes as indicated on the template.
d. Attach the appropriate model housing to the air duct using two No. 10 1½ inch screws (6) and also
using two No. 10 1-inch screws (7) with lockwashers (8).
e. Cut a 12 inch by 12 inch access hole in the duct adjacent to the housing to permit checking and
cleaning of the sampling tubes. The access hole must be covered and sealed when not in use.
Sampling Tube Selection
To insure accurate air sampling, inlet sampling tubes are available in four lengths. To select the
appropriate length, determine the outside width of the duct. Select the sampling tube nearest to, but
greater than, the duct width (Table 1). The outlet sampling tube for all ducts is a fixed length of 4
inches (10.1 cm). Trim the inlet sampling tube at the job site as described below.
Outside Duct Width
1 ft 9 ¾ in or less
1 ft 9 ¾ in - 3 ft 3 ¾ in
3 ft 3 ¾ in - 6 ft 3 ¾ in or less
6 ft 3 ¾ in - 9 ft 9 ¾ in or less
Greater than 9 ft 9 ¾ in
Note: Each model is manufactured with a different number and size of hole. Therefore, only the
specific tube must be used for the specified duct width.
Trimming the Inlet Sampling Tube (See Figure 4)
a.
Measure the outside width of the duct.
b.
Add 2.25 inches to obtain proper length of tube.
Example:
c.
Measure the sampling tube, starting from the end with the four mounting holes.
d.
Trim tube to the correct length, remove all burrs, and insert a rubber stopper (Figure 3,
Item 9) in the tube.
TABLE 1 - Sampling Tube Selection Chart
Sampling Tube Model No.
Figure 4
Sampling Tube Orientation
Outside width of duct
Add 2.25 inches
Length of sampling tube
The length (2 ft 8.25 in) determines (Table 1 above) the model
number of the appropriate sampling tube (STA-3).
STA-2
STA-3
STA-6
STA-10
Consult factory
2 ft 6in
+
2.25 in
2 ft 8.25 in
4
Standard Tube Length
2 ft
3 ft 6 in
6 ft 6 in
10 ft
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