Several considerations for selecting a thermometer
measurement error
When conducting high-precision resistance measurements, it is important to ensure that the thermometer can eliminate thermoelectric potential errors generated at different metal connections in the measurement system. A common technique for eliminating thermoelectric errors is to use switch mode DC or low-frequency AC current sources.
resolving power
Be careful with this indicator. Some thermometer manufacturers confuse resolution and accuracy. A resolution of 0.001 ° C does not necessarily mean an accuracy of 0.001 ° C. Generally speaking, a thermometer with an accuracy of 0.001 ° C should have a resolution of at least 0.001 ° C. When detecting small temperature changes, display resolution is very important - for example, when monitoring the solidification curve of a fixed point container or checking the stability of a calibration slot.
Linearity
Most thermometer manufacturers provide accuracy technical indicators at a temperature (usually 0 ° C). This is very useful, but you usually need to measure a wide temperature range, so it is very important to understand the accuracy of the thermometer within its working range. If the linearity of the thermometer is very good, then its accuracy index will be the same throughout its entire temperature range. However, all thermometers have a certain degree of nonlinearity and are not completely linear. Please ensure that the manufacturer provides accuracy technical indicators within the scope of work, or provides linearity technical indicators that you use when calculating uncertainty.
stability
Due to the need to measure under a wide range of environmental conditions and over various time periods, reading stability is crucial. Ensure to check the temperature coefficient and long-term stability indicators. Ensure that changes in environmental conditions do not affect the accuracy of the thermometer. Renowned manufacturers provide temperature coefficient indicators. Long term stability indicators are sometimes combined with accuracy indicators, such as "1ppm, 1 year" or "0.01 ° C, 90 days". It is difficult to calibrate every 90 days, so it is necessary to calculate the one-year indicator and use it for uncertainty analysis. Beware of providers that offer '0 drift' metrics. Each thermometer will have at least one drift component.
