What is the coefficient of thermal expansion (CTE) of [insert substance here]?
For gages, the manufacturer should give you this information. If they dont, you have at least a small problem. Looking in a reference book for the coefficient of thermal expansion (CTE) involves a number of assumptions. a. When I look up steel in the reference book, is it the same steel as my gage? The more information you have the better. A worse case example is stainless steel where 300- and 400-series stainless steels have CTE around 10 µm/m/°C and 18 µm/m/°C, respectively. If you do not know which you have, the uncertainty in the CTE is rather large. b. Reference book values are averages over a given temperature range, and a competent reference will at least give you the range. Since the CTE varies with temperature, the average CTE over the temperature 0 °C to 200 °C leaves a fair amount of uncertainty in the value you need, at 20 °C. The upshot is that you must do your best. If the manufacturer does not give you a value and uncertainty you must scramble about and make sure you est
