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S8000 -100 User Manual
18
97606 Issue 1, June 2021
OPERATION
3.4
Manual Mode
3.4.1 Description
When the instrument is switched on, the cooler set-point will initially be +20 °C
(+68 °F). The user is responsible for selecting the appropriate sensor temperature set-
point via the Cooler Setup Page.
3.4.1.1 Operating Practice
The S8000 -100 will only be capable of measuring dew points down to -50 °C
(-58 °F) with the cooler temperature set to +20 °C (+68 °F). When measuring dew points
below -50 °C (-58 °F), it is necessary to set the sensor temperature to approximately
30 °C (54 °F) above the dew point to be measured in order to maintain a fast speed of
response.
If the dew point is not known, then it is advisable to operate in automatic mode to
allow the instrument to find the correct temperature autonomously. If manual cooler
operation is essential, the following steps should be taken to determine the dew point,
before setting the cooler temperature:
1. Ensure that the mirror is clean and the sample flow rate is correctly set to 750ml/
min (1.6 scfh).
2. Switch the instrument on.
3. Ensure the sensor temperature is set to +20 °C (+68 °F).
4. After the DCC is complete, the S8000 -100 will cool the mirror down:
a.
If the dew point is wetter than -55 °C (-67 °F):
i.
The instrument will cool the mirror below -55 °C (-67 °F).
Frost will then begin to form on the mirror, after which the
mirror temperature will start to increase and settle on the
dew point.
ii.
The S8000 -100 will only measure this dew point for
approximately 40 minutes with the cooler temperature set
to +20 °C (+68 °F). Once the dew point has been found,
set the cooler temperature to approximately 30 °C (54 °F)
above the dew point.
b.
If the dew point is dryer than -55 °C (-67 °F):
i.
The instrument will cool the mirror down to approximately
-55...-65 °C (-67...-85 °F) (depending on the actual sensor
temperature). When the mirror has been cooled to the
minimum temperature possible, it will remain at that value.
However, due to heat generated by the Thermo-electric cooler
cooling at the limit of its capacity, the mirror temperature
will gradually increase.
ii.
Observing the mirror through the microscope will confirm
that there is no frost on the mirror, and therefore the dew
point is lower than the displayed mirror temperature.
Summary of Contents for Michell Instruments S8000 -100
Page 1: ...S8000 100 Chilled Mirror Hygrometer User Manual 97606 Issue 1 June 2021 nbn Austria GmbH ...
Page 51: ...S8000 100 User Manual Michell Instruments 43 APPENDIX A Appendix A Technical Specifications ...
Page 54: ...S8000 100 User Manual 46 97606 Issue 1 June 2021 APPENDIX B Appendix B Modbus Register Map ...
Page 67: ...S8000 100 User Manual Michell Instruments 59 Notes ...