5
Sampling Tube Selection
There are four standard lengths of inlet sampling tubes. To ensure accurate
air sampling, select the appropriate length and determine the outside width of
the duct. Select the sampling tube nearest to, but greater than, the duct width
(Table 2). 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.
TABLE 2
SAMPLING TUBE SELECTION CHART
Sampling Tube
Standard
Outside Duct Width
Model No.
Tube Length
1 ft 9
3
/
4
in or less
8932
2 ft
1 ft 9
3
/
4
in - 3 ft 3
3
/
4
in
8933
3 ft 6 in
3 ft 3
3
/
4
in - 6 ft 3
3
/
4
in or less
8934
6 ft 6 in
6 ft 3
3
/
4
in - 9 ft 9
3
/
4
in or less
8935
10 ft
Greater than 9 ft 9
3
/
4
in
Consult factory
Note: Each model is manufactured with a different number and size of
sampling hole. Only the specific tube must be used for the specified
duct width.
Figure 4
Sampling Tube Orientation
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