Shaw SDHmini Bl, Инструкция по эксплуатации

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3.0 Installing the Air/Gas Sampling System
The
Piping Installation Schematic
diagram (see section 3.2) shows all components,
which could be used in a dry gas measurement application. Although not all the
items shown will be required for every installation.
The SDHmini should be placed on a stable surface prior to connecting to the
sample pipework. Care should be taken to ensure that the sample presented
to the SDHmini is not contaminated with any component that will damage,
contaminate or affect in a way that will impair the unit’s accuracy.
The flow rate, although not critical to the sensor measurement, should be low
enough to avoid abrasion to the sensor surface without being so low as to extend
the SDHmini response time to an unacceptable level. In general, a flow rate of
between 2 and 5 litres/min at NTP will give the right balance.
The SDHmini is designed to be operated at atmospheric pressure with a
maximum of 0.3 bar.
3.1 Gases to Avoid
The moisture sensors are suitable for any different industrial and research
applications. Most gases can be checked for their moisture content with no
need for the calibration to be altered when changing between different gases,
as the sensor operates only with reference to the water vapour content.
There are however, some gases that must be avoided as they are not compatible
with the material of construction of the sensor. Ammonia (NH
3
), Ozone (O
3
) and
Chlorine (Cl) must be avoided at all times, even in small quantities. Hydrogen
Chloride (HCl) also attacks the sensors very quickly. Some, less aggressive acidic
gases such as Sulphur Dioxide (SO
2
) can be monitored as long as the moisture
content is low, generally less than 100ppm(v). If in doubt, please ask your
supplier.
Sulphur Hexafluoride (SF
6
) has no effect on the sensor. If the gas has been
exposed to arcing, however, it is possible that various acidic species will have
been formed that will corrode the sensor. When testing SF
6
that may have been
arced, therefore, an acidity test should be carried out first; if the gas proves to
be acidic then the moisture test should not be carried out.
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