Kahn Optisure Remote, User Manual

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Optisure Remote User’s Manual
Kahn Instruments 25
OPERATION
4. Particulates – particulates passing over the sensor can build up on the mirror
over time. This can cause a loss of mirror reflectivity. DCC will compensate
for this by taking into account anything on the surface of the mirror when
resetting the optical condition, however if the problem becomes too severe,
the ‘optics warning’ symbol will be displayed in the Sensor Status display.
5. Sample temperature – consider the difference between the sample
temperature and the dew point temperature. Make sure that the sensor you
are using has the cooling capability to make the measurement (see section
4.5.7 for further information).
If the sensor does not have the necessary cooling capability, then you should consider
an extractive system so the sample can be cooled prior to measurement.
6. Sample pressure – If you are interested in readings in terms of ppm
V
or g/m
3
Insure that the sensor is positioned in an environment of known pressure.
You can then either enter this pressure into the Optisure Remote via the
Application Software, or connect a pressure sensor directly to the point of
measurement (see section 2.5.9).
Extractive
If the sensor will be mounted into a sample conditioning system, then the above points
are still of relevance, but the following should also be considered:
1. Extraction point – make sure that the chosen extraction point is representative
of the process, i.e. that the sample of interest is flowing past the extraction
point, and it is not being pulled from a dead volume.
2. Enclosure and sample line heating – if the sample has a dew point greater
than ambient temperature, then all components upstream of the sensor will
need to be heated to at least 10°C above the sample dew point to insure
the water remains in vapor phase.
Figure 21 Sample Block
4.3 Good Measurement Practice
4.3.1 Sampling Hints
Measurement of moisture content is a complex subject, but does not need to be difficult.
This section aims to explain the common mistakes made in measurement situations, the
causes of the problem, and how to avoid them. Mistakes and bad practices can cause
the measurement to vary from the expectation; therefore a good sampling technique is
crucial for accurate and reliable results.