Appendix B Temperature And Relative Humidity Calibration; Temperature And Relative Humidity Calibration; Thermistor Calibration - ACR Electronics SmartReader Plus Reference Manual

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SmartReader Plus Data Loggers

1.16

APPENDIX B Temperature and Relative Humidity Calibration

1.16.1

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.

1.16.2

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.

List of Materials

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.

Label each thermistor sensor so that later you can easily match it to the calibration

equations you produce.

Allow the thermistor and thermometer to stabilize at room temperature around 25°C

(77°F). Record both temperature and resistance readings, being careful not to handle

both devices. This is the Mid calibration point data.

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).

Temperature and

Relative Humidity

Calibration

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