Vaisala HMP4 - Adjustment Points and Requirements; HMK15 Humidity Calibrator with HMP Series Probes

When returning a product for calibration or repair, make sure it
has not been exposed to dangerous contamination, and is safe to handle
without special precautions.
WARNING!
If you think the device is not measuring correctly, calibration and adjustment is
not the first thing to do. Check the following first:
• Make sure nothing is interfering with the measurement: heat sources,
temperature dierences, or condensation.
• Check that there is no moisture on the probe. If the sensor has become wet,
wait for it to dry.
• Always wait for the measurement to stabilize.
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.
7.4.1 Adjustment points and requirements
You can adjust the humidity measurement in 1 … 5 points, and temperature measurement in
1 … 2 points. Note the following:
• Humidity adjustment in more than two points is available when using Insight software in
Advanced Mode.
• If you are adjusting in more than one humidity point, make sure the first two points are at
least 10 %RH apart.
• The probe will reject adjustments that are too large, that is, greater than 10 %RH for
humidity and 0.5 °C for temperature. If the probe appears to need such a large correction,
perform a sensor purge and repeat the adjustment procedure. Make sure the
measurement has stabilized and the reference environment is reliable. If the required
adjustment is still too large, the probe needs to be serviced by Vaisala.
When adjustment of humidity measurement is necessary, Vaisala recommends
adjusting in two points, 11 %RH and 75 %RH. These humidities can be produced
using the Vaisala HMK15 Humidity Calibrator.
Adjustment of temperature measurement is typically not necessary.
7.4.2 HMK15 Humidity Calibrator with HMP Series probes
Vaisala HMK15 Humidity Calibrator is a suitable humidity reference for HMP Series probes.
When preparing the salt solutions and using the calibrator, follow the general instructions in
the HMK15 User Guide (M210185EN) to avoid common sources of calibration error.
Chapter 7 – Maintenance
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