Sensorsoft Temperature and Humidity Meter User’s Manual
Resolution, Accuracy and Calibration
The terms resolution, accuracy and calibration frequently cause misunderstanding for many
individuals who have not been trained in metrology. We explain these terms here and how they
might apply to your application of Sensorsoft devices.
Resolution or precision is the fineness of the measurement. It is usually specified in terms of the
smallest unit that can be resolved.
Accuracy is the trueness of the measurement or how close it can be to the true value (National
Standard). Accuracy is often specified as a percentage (i.e. +/- 3 %) of the reading, or a fixed
value (i.e. +/- 0.5) that can vary from the true value of the reading.
Calibration is a process where accuracy is verified (and often corrected) with respect to a
standard. Calibrations are routinely carried out to certify that a device has not lost its accuracy,
linearity and stability. Calibrations can be carried out at a time interval that is required by your
industry. In many cases, this is at least once every year.
When a calibration or verification takes place, it must always be done with equipment that has
significantly better accuracy and resolution then the device under testing. When a calibration
check is performed on a “Unit under Test” with an instrument traceable to the National Standards
Laboratory, the “Unit under Test” is also considered to be traceable.
Avoiding invalid judgments or comparisons
Using any of the following measurement devices or situations is unacceptable for comparing to,
or judging the accuracy of a Sensorsoft device:
Low cost measurement device purchased from a retail store
Digital display on HVAC or cooling/heating equipment
Location of the active sensing element is unknown or hidden
Measurement device has its active sensing element more than one inch (2.5 cm) away from
the Sensorsoft device’s sensing element
Measurement device has lower accuracy specifications as compared to the Sensorsoft device
Measurement device has unknown accuracy specifications
Measurement device has not been calibrated within one year, has no calibration certificate or
is not traceable to a reference standard
Appropriate measurement instruments to making comparisons
We recommend one of the following instruments (or equivalent with a recently dated traceable
calibration certificate) for judging the accuracy or stability of your Sensorsoft device:
Vaisala HM40 series Hand held Humidity & Temperature Meter (approx. price $500-1000
US)
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