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SmartReader Data Logger

1.14

APPENDIX B Temperature and Relative Humidity Calibration

Temperature and

Relative Humidity

Calibration

1.14.1 Temperature and Relative Humidity Calibration

This chapter provides instructions on how you can recalibrate your RH modules, EH-020A

External Temperature and Relative Humidity probes and any thermistor temperature probes.

1.14.2 Thermistor Calibration

If you do not have accurate resistance-temperature data on your thermistors (available with all

interchangeable types) and want to calibrate your own, or simply want to confirm sensor

accuracy, you can perform a simple calibration procedure that will give you the right

information.

Items You Will Need

Here is a list of items you will need:

· an accurate thermometer, preferably one with 0.1°C increments or better

· a bucket

· crushed or chipped ice

· a pot of boiling water

· a digital multimeter, preferably one with 0.1% resolution, or better

Test Procedure

Make sure the thermistors and leads you want to test are properly potted (waterproofed),

insulated or otherwise protected against moisture. You should not dip an unprotected

thermistor in water since the water will short the leads and produce false readings. For this

procedure use Equation 44.

1. Label each thermistor sensor so that later you may easily match it to the calibration

equations you produce.

2. Fill the bucket with the crushed or chipped ice. Add water so that it overflows. Add more

ice until it is tightly packed right to the bottom of the bucket (allowing water to overflow).

3. Insert the thermometer and the thermistor probes into the bucket ensuring that they do

not touch the side or bottom of the bucket. Make sure the thermistor probes' leads are

long enough for you to easily take resistance readings.

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ACR Electronics SmartReader Plus Manual do Utilizador Página 77