An e-newsletter published by Moore Industries Inc., North Hills, Calif., has some advice for anyone struggling with temperature stability in an industrial process.

To improve long-term stability of temperature measurement, Moore offers the following suggestion: Start with a Class A four-wire RTD, but pay attention to another critical selection criterion for RTDs - make sure they have been thermally aged.

The sensors the company uses in high accuracy applications have been temperature-cycled from 32 to 1,112°F (0 to 600°C) for 1,000 hours, according to Moore. The annealing makes them virtually drift-free for the next five to 10 years, the company says.