Fluke 5686, User Manual, Page: 9 / 16

1
Introduction
The Fluke Calibration Glass Capsule Standard Platinum Resistance Thermometer (SPRT) is
designed to be the best primary standard interpolating instrument converting temperature to
resistance. The Fluke 5686 Glass Capsule SPRT is a member of the Fluke Calibration SPRT
family (Figure 1). The 5686 SPRT is primarily designed for the following two applications: used
in low temperature range down to 13 K (–260 °C), or used where a totally immersed probe is
prefered to minimize the heat flow from or to the sensor. Long stem SPRTs are not suitable for
some applications where the probe should be encased into a vessel completely. The 5686 SPRT
covers the range from 13 K (–260 °C) to 505 K (232 °C).
The 5686 is carefully annealed at the appropriate temperatures and precisely tested for stability.
The sensing elements are fabricated using high-purity platinum wire wound in a strain-free design
on a fused silica cross frame. The special glass capsule of the 5686 is pressure sealed with 5N
pure helium.
5686.tif
Figure 1. 5686 Glass Capsule Standard Platinum Resistance Thermometer
Before You Start
Symbols Used
Table 1 lists the International Electrical Symbols. Some or all of these symbols may be used on
the instrument or in this manual.