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8.0 RH and T adjustment of the probes
8.1 Definitions
Calibration
The calibration documents the accuracy of a measurement
device. The device under test (specimen) is compared
with the reference and the deviations are documented in a
calibration certificate. During the calibration, the specimen
is not changed or improved in any way.
Adjustment
The adjustment improves the measurement accuracy of a
device. The specimen is compared with the reference and
brought in line with it. An adjustment can be followed by a
calibration which documents the accuracy of the adjusted
specimen.
8.2 Sensing adjustment with SRH400 basic
device
• 1-point RH or T adjustment for optimal performance over
a narrow RH or T range.
Example: climate monitoring in a pharma manufacturing
site. RH range: 40…60 % RH, RH adjustment point: 50 %
RH T range: 15…25 °C (59…77 °F) T adjustment point: 20
°C (68 °F)
• 2-point RH or T adjustment for accurate measurement
over a wide RH or T range.
Example: outdoor measurement
RH range: 10 … 100 % RH, RH adjustment points: 40
% RH, 70 % RH T range: -30 … 35 °C (-22...95 °F), T
adjustment points: -10 °C (14 °F), 15 °C (59 °F)
• The adjustment data is saved into the probes. The SRH400
basic unit is not affected by the adjustment procedure.
Consequently, it is possible to replace the probes at any
moment.
• Start the adjustment procedure with the low point (e.g. 30
% RH) and continue with the high point (e.g. 80 % RH)
• For accurate calibration or adjustment, the specimen and
the reference must have same T.
• During calibration or adjustment the T shall remain
constant.
• Allow min. 30 min, stabilization time for RH calibration or
adjustment.
• If needed, clean the sensors and replace the filter cap by
a new one.
8.2.1 2-point RH and T adjustment
1. Set the jumper to RH calib or to T Calib.
2. Place the probe into the corresponding calibrator and let
it stabilize at the first point (low) for at least 30 minutes.
3. Press and hold S2 for 3 seconds. The LED “Calib” will light
and the symbol “CAL<” will appear on the SRH400 display.
4. Push S1 (up) or S2 (down) to bring the measured
value in line with the reference in steps of 0.1. The
actual corrected value is indicated on the display
and can be measured at the analogue output.
5. Press and hold S1 for 3 seconds to store the value into the
probe and end the first (low) point adjustment. The LED
“Calib” will be deactivated and the display will show “CAL”
6. Alternative: Press and hold S2 for 3 seconds to exit
the adjustment mode without storing the adjustment
data. The LED “Calib” will be deactivated and the
symbol “CAL” disappears from the LC display.
7. Set the calibrator for the second (high) adjustment
point and let the probe stabilize for at least 30 min.
8. Press and hold S1 for 3 seconds. The LED “Calib” will light
and the symbol “CAL>” will appear on the SRH400 display.
9. Push S1 (up) or S2 (down) to bring the measured value
in line with the reference in steps of 0.1. The actual
corrected value is indicated on the display and can be
measured at the analogue output. Press and hold S1 for
3 seconds to store adjusted value in the probe and end
the second (high) point adjustment. The LED “Calib”
will be deactivated and the display will show “CAL”.
Alternative: Press and hold S2 for 3 seconds to
exit the adjustment mode without storing the
adjustment data. The LED “Calib” will be deactivate
and the symbol “CAL” disappears from the LC display.
