Appendix 3: Calibration Basics - Rotronic Instruction Manual

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Appendix 3: Calibration Basics

Calibration of the HygroClip probes requires the following:
a) HW3 installed on a PC
b) calibration cable MOKX-03-WIN or T7-03-WIN (depending on probe)
c) adjustable temperature and humidity reference (such as a Rotronic humidity standard)
Temperature Calibration
Note: the stability of the Pt100 RTD sensor used to measure temperature is such that
temperature calibration in the field is seldom required.
In order to be able to correctly evaluate the accuracy of the temperature measurements
provided by the probe, you should be able to meet the following requirements:
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.
Humidity Calibration
ROTRONIC provides easy-to-use, certified humidity standards for those customer 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).
The following calibration devices are available from ROTRONIC:
ER-15: for 15mm diameter probes
ER-05: for 5 mm diameter probes
EM-15 for probe type IE
ERV-15 for probe type IW
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HygroLog - 12/05/2001