Abstract. Mass spectrometric analysis shows that platinum resistance thermometers become contaminated by exposure to Ag and Cu at high temperatures. To study the rate at which such contamination occurs, bundles of Pt wires in quartz tubes were soaked in a silver fixed-point furnace. The results suggest that the sensing element of a platinum resistance thermometer (PRT) inserted into an Ag-contaminated thermometer well will begin to become contaminated after approximately 400 hours of accumulated use at the silver point. The experimental results suggest that the contamination may be avoided by interposing an additional, disposable quartz tube between the contaminated thermometer well and the PRT.

Print publication: Issue 5 (1994)
Received 24 March 1993