Platinum resistance reference thermometer
-200 - 1070 °C | 5681 / 5683 / 5684 / 5685
Hart has four quartz-sheath SPRTs covering the ITS-90 range of –200 °C to 1070 °C. The 5681 is used from –200 °C to the aluminum point at 660.323 °C. The 5683 is used from –200 °C to 480 °C with greater long term stability. The 5684 and the 5685 cover higher temperatures up to 1070 °C and can be calibrated at the silver point.
Yes, they have all the features you would expect in a world-class SPRT. They have gold-plated spade lugs, a strain-relieved connection to the four-wire cable, convection prevention disks, the finest quartz glass available, delustered stems, and the purest platinum wire available.