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FIGURE 3: THE NOZZLE. FIGURE 5: A COMPLETE STACK TESTING
TRAIN FOR PARTICULATES.

FIGURE 4: THE PROBE (LINER AND SHEATH). stream and two upstream from a flow disturbance,
the required minimum number of traverse points for
a circular or rectangular cross section is determined
from Figure 6.
The minimum number of traverse points for ve-
locity sampling is shown in Figure 7.
Once the total number of traverse points has been
determined, the location of where the nozzle is to be
placed (i.e. traverse points) has to be made. Locate
the sampling points on the traverse from the table in
Figure 8. This will give you the placement of the
sampling nozzle from the stack wall.
An example calculation has been made for a seven-
foot diameter stack and shown in Figure 9. A sum-
mary of traverse locations is shown for circular and
rectangular cross section stacks in Figure 10 based on
the example calculation of Figures 7, 8 and 9.

quartz or glass. Figure 4 shows a schematic of the probe.
FIGURE 6: MINIMUM NUMBER OF TRAVERSE POINTS FOR
A complete stack testing train for particulates is shown in Fig- PARTICULATE SAMPLING WITH FLOW DISTURBANCE.
ure 5. Modifications are made to this train depending on the pa-
rameters to be sampled.

Location of Sampling Site and Traverse Points
When sampling a stack, the location of the sampling site and loca-
tion of traverse sampling points are important to optimize the
extraction of a representative sample. The ports on the stack
(where the probe enters the stack) can be established during the
stack test if none exist. The traverse points are located on the stack
diameter on perpendicular axes.
Select a site in a straight section of stack or duct located at least
eight stack or duct diameters downstream and two stack or duct
diameters upstream of any flow disturbance (e.g. a bend, an expan-
sion, a contraction, visible flame, junction, or stack exit).
In circular stacks or ducts, at least two sampling ports with a 90-
degree separation are required. This means that sampling is done
on two perpendicular axes.
When the sampling site is located at least eight diameters down-
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