Instructions for Use SS 20.60
Page 5/16
4 Determination of the position of installation
To reach the accuracy specified in the data sheets, the sensor
has to be positioned in a straight conduit and at a place with
undisturbed flow profile. An undisturbed flow profile can be
achieved if a sufficiently long distance in front of the sensor (run-in
distance) and behind the sensor (run-out distance) is held
absolutely straight and without disturbances (such as edges,
seams, bends, etc.).
The design of the run-out distance is also important, since
disturbances do not only act
in
the direction of the air flow but also
lead to turbulence
opposite
to the flow direction.
run-in distance L1
run-out distance L2
D
Figure 1: Sensor position in the pipe
L= total length of the measuring distance, L1 = length of the run-in
distance, L2 = length of the run-out distance, D = diameter of the
measuring distance
The sensor tip must be positioned in the center of the pipe
opening as shown in Figure 1
.
The following table shows the necessary straight conduit lengths
as a function of each disturbance.
L
