ROTRONIC HygroLab - Manual (Page 32)

IN-E-HyLab-V4_11
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
Instruction Manual
Document Type
HygroLab bench top indicator version 4:
instruction manual
Document title
Page 32 of 51
© 2006; Rotronic AG IN-E-HyLab-V4_11
a) Both the probe and a reference thermometer should be ventilated with the same stream of
air. Any dust filter used to protect the sensors should be carefully removed from the probe.
If the probe has a protective slotted cap, this may be left on the probe.
b) Air velocity at the sensor should be within the limits of 200 to 500 feet/minute (1 to 2.5
meters/second). Any comparison between two instruments at a velocity under 200
feet/minute may not be valid. Air velocity above 500 feet/minute may damage the
unprotected humidity sensor.
c) The temperature of the air stream should be practically constant.
If you cannot meet the above requirements, you should not attempt to calibrate temperature.
13.2 Humidity calibration
ROTRONIC provides easy-to-use, certified humidity standards for customers who do not have
access to a humidity generator. To use these standards, you will need a calibration device that
is suitable for your probe.
Calibration device
The calibration device is a small airtight container that fits on the probe and seals around the
humidity sensor. During calibration, a known reference humidity is produced inside the
calibration device by means of a humidity standard (usually an aqueous salt solution). To find
out which model of calibration device is suitable for your probe, please consult the probe
documentation.
Certified humidity standards
The ROTRONIC certified standards are available in boxes of 5 glass ampoules of the same
value, which can be stored indefinitely. Standards in the range of 5 to 95 %RH are non-
saturated aqueous salt solutions that are precisely titrated at our factory for the right
concentration. The 0 %RH humidity standard is made of small granules of a highly porous
ceramic that have been dried at a high temperature. A Material Safety Data Sheet is available
for each standard. Since most standards are a salt solution, parts which have come in contact
with the liquid should be cleaned after each use.
Each box of standards comes with a certificate that provides statistical information on the
manufacturing batch of the standard. Information on the effect of temperature on each
standard is provided on the cover of each box of standard. When calibrating either with the
HygroLab or with the HW4 software, the effect of temperature on the standards is
compensated by the software and no further correction is required. The value of the standards
is not affected by altitude.