Schmidt SS 20.501 Mode D'emploi page 22

Table of run-in and run-out distances
Flow obstacle upstream of the
measuring conduit
Light bend (< 90°)
Contraction (conduit contracts
toward the measuring area)
Expansion (conduit expands
toward the measuring area)
90° bend or T-junction
Two 90° bends in one plane
Two 90° bends with 3-
dimensional change in direction
Shut-off valve
This table lists the minimum values required in each case. If the listed straight
conduit lengths cannot be achieved, the measurement accuracy may be im-
paired.
The sensor should not be mounted in the proximity of heat sources, since this
may result in measurement errors. When used in ventilation pipes equipped with
heat exchangers, the sensor should always be mounted upstream of the heat
exchanger.
Mounting position
In order to achieve maximum measuring sensitivity, the sensor tip should be
mounted pointing upwards or horizontally. A sensor tip pointing downwards must
be avoided, since this will increase the measuring range limit (nominal value 0.06
m/s).
Minimum length of the
run-in distance (L1)
10 x D
15 x D
15 x D
15 x D
20 x D
35 x D
45 x D
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Minimum length of the
run-out distance (L2)
5 x D
5 x D
5 x D
5 x D
5 x D
5 x D
5 x D