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Appendix B — Humilab chilled mirror hygrometer
tory calibrated and normally do not require repeat calibration or
field adjustment.
Service and troubleshooting procedures
This section deals with some procedures that are performed on a
day-to-day basis by the operator, but contains additional elements
and covers procedures appropriate only for trained electronic tech-
nicians.
Test and
calibration
The procedures in this section test and/or calibrate the following
aspects of the Electronics Module:
• Start-up and power supply voltage
• Normal sensor operation
• Front panel display
• Digital and analog outputs
The Electronics Module has been completely tested and calibrated
at the factory, and is ready to plug in and operate. As received, it
meets all of our published specifications.
When ordered as a complete hygrometer system with a chilled
mirror sensor and cable, the system is checked at a number of
points against a dew point system that has been certified by the
U.S. National Institute of Standards and Technology (N.I.S.T.). A
Certificate of Conformance is supplied with it to indicate trace-
ability.
There are no calibration adjustments in the instrument that affect
the digital display. The displayed reading is a microprocessor calcu-
lation from the platinum Resistance Temperature Detector (RTD)
that measures the mirror temperature, which is controlled auto-
matically at the dew point.
