DURAG D-R 290, Operating Manual

Page: 68 / 202

5 | Installation
68 D-R 290
Within the measurement duct…
▶
…the distribution of the dust and smoke within the gas should be as homogeneous
as possible
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…the dewpoint of the flue gases should not be undershot
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...the path of the light beam through the gas to be measured should be as nearly
horizontal as possible.
The measuring point should not be just before or just after bends in the duct or
changes in its cross-section. The upstream section (duct section leading up to the
measuring point) should be at least 5 × D (D = internal diameter of the duct) and the
downstream section (duct section leading away from the measuring point)) should be
at least 2 × D (see Fig. 5.2 a). If no such location is available, the upstream section (A)
should be longer than the downstream section (see Fig. 5.2 b).
On flues with round internal cross-sections, "D" means the internal diameter. In the
case of square or rectangular cross-sections, the hydraulic diameter is used:
Equation
10
F Area
U Scope
Table 5.2: Equation 10
The installation location should be as free from vibrations and oscillations as possible.
If this is not possible, it is recommended that the installation it keep away from
draughts that might induce vibration, so that the measuring system is not subject to
stresses.
Fig. 5.2: Measuring point
If a measuring point is sought between a filter and an induced draught, then the instal­
lation point should be placed more towards the induced draught and less towards the
filter.