Vaisala RFL100 - Calibration and Adjustment Using HM40

Calibration means comparing the measurement output of the device to a known
reference, such as a known environment in a calibration chamber or the output of
a reference instrument. Correcting the reading of the device so that it measures
accurately is referred to as adjustment.
Sensors and measurement electronics used by the data logger are fully contained in the
replaceable probe. This allows the probe to be calibrated, adjusted, and replaced as needed.
The calibration frequency depends on the application and your compliance requirements.
Vaisala recommends having the probe calibrated and adjusted once a year by Vaisala
Calibration and Repair Services. See www.vaisala.com/calibration.
Generic procedures for on-site calibration and adjustment are provided in this guide:
• To verify the measurement accuracy of the probe without disconnecting it from the data
logger, compare its readings with a calibrated reference instrument. Doing this at the
installation location of the data logger is referred to as a
field check. See Field Checking
Using a Reference Instrument (page 30).
• To calibrate and adjust the probe using humidity and temperature references, connect the
probe to compatible Vaisala humidity and temperature meter. See Calibration and
Adjustment Using HM40 (page 30) and Calibration and Adjustment using MI70
(page 36).
5.5.1 Field Checking Using a Reference Instrument
You can perform a field check of the RFL100 using any humidity and temperature
measurement instrument with a display. Typically field checking is done with a recently
calibrated portable instrument.
1. Place the probe of the reference instrument (or the entire instrument) in the same
environment as the probe of the RFL100. The environment should be as stable as
possible.
2. Wait for 30 minutes for humidity and temperature to stabilize. Verify that measurements
are no longer changing at the end of the stabilization period.
3. Record the readings from both instruments.
5.5.2 Calibration and Adjustment Using HM40
• Vaisala HM40 Hand-Held Humidity and Temperature Meter
• Connection cable for HM40 Hand-Held Meter (Vaisala item HMT120Z300)
• Reference environments for the desired calibration points
• RFL100 data logger with the probe to be calibrated
RFL100 User Guide M211861EN-A
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