If you’re using block calibrators, furnaces, or temperature points above normal PRT (platinum resistance thermometer) temperatures (420 °C), then these two PRTs are for you. The 5626 is nominally 100W and the 5628 is nominally 25.5W. Both instruments have a temperature range of –200 °C to 661 °C. They make great working or check standards for calibration work up to the aluminum point.

Using a regular PRT at temperatures above 500 °C exposes the platinum to contamination. If the PRT is used as a reference or calibration standard, contamination is a major problem. SPRTs (standard platinum resistance thermometers), which are more expensive and delicate, can handle the higher temperatures, but with greater risk to the instrument due to shock, contamination, or mishandling. The 5626 and 5628 are designed to reduce the contamination risk through the use of internal protection while not impairing performance.

In addition to the right measurement performance and durability, a PRT for secondary applications should be priced affordably. Fluke Calibration’s new PRTs are inexpensive and come with an accredited calibration. The calibration comes complete with ITS-90 constants and a resistance-versus-temperature table.