Designed for metrology work requiring small SPRTs
- Temperatures from –260 °C (13 K) to 232 °C
- Stability typically 0.001 °C over 100 °C range
- Miniature capsule package eliminates stem conduction
Sometimes you would like to make SPRT measurements but traditional SPRTs are too long or awkward for a particular application. Now Fluke Calibration makes a miniature glass capsule SPRT, which is perfect for cryogenics, calorimetry, and other metrology work requiring small SPRTs.
The 5686 is a true SPRT. The high-purity platinum wire is hand-wound on a glass cross frame in a strain-free design. The glass capsule is designed to match the thermal expansion of the platinum wire to ensure a true seal at all operating temperatures. The capsules are pressure sealed and come protected in their own maple case.
The 5686 complies completely with ITS-90 and has the following resistance ratios:
W(302.9146 K) ≥ 1.11807
and
W(234.3156 K) ≤ 0.844235
The 5686 covers temperatures from –260 °C to 232 °C, so it’s perfect for cryogenic applications. It is 5.8 mm in diameter and 56 mm long. Fixed-point calibrations are available for the model 5686 from –200 °C to 232 °C.
These SPRTs are small but meet customary SPRT performance for reproducibility, reliability, and stability. They solve many of the problems associated with taking precision measurements in situations unsuitable for traditional-length SPRTs.
| Specifications | |
| Temperature Range | 5686: –260 °C to 232 °C (13 K to 505 K) |
| Nominal RTPW | 25.5 Ω |
| Resistance Ratio | W(302.9146 K) ≥ 1.11807 W(234.3156 K) ≤ 0.844235 |
| Drift Rate | 5686: < 0.005 °C per year over the entire range |
| Self-heating at TPW | < 0.002 °C under 1 mA current |
| Reproducibility | ±0.001 °C or better |
| R TPW Drift After Thermal Cycling | < 0.001 °C |
| Filling Gas | 5686: helium |
| Lead Wires | Four platinum wires, 30 mm long (1.18 in) |
| Size | 5686: 5.8 mm dia. x 56 mm long (0.23 x 2.2 in) |
5686 Statement of Memory Volatility (117.07 KB) 
