Fluke 5681/ 5683/ 5684 Quartz-Sheath SPRTs

Manufacturer: Fluke Calibration
Model: 5681/ 5683/ 5684

Features

Drift rates as low as 0.0005 K
Proprietary gas mixture ensures high stability
Most experienced SPRT design team in the business

Specifications

Specifications568156835684
Temperature Range–200 °C to
670 °C
–200 °C to
480 °C
0 °C to
1070 °C
Nominal RTPW25.5 Ω0.25 Ω
Current1 mA14.14 mA
Resistance RatioW(302.9146 K) ≥ 1.11807 and
W(234.3156 K) ≤ 0.844235
W(302.9146 K) ≥ 1.11807 and
W(1234.93 K) ≥ 4.2844
Sensitivity0.1 Ω/°C0.001 Ω/°C
Drift Rate< 0.002 °C/100
hours at
661 °C (typically < 0.001 °C)
< 0.001 °C/100 hours at
480 °C (0.0005 °C typical)
< 0.003 °C/100 hours at 1070 °C
(typically < 0.001 °C)
Sensor SupportQuartz glass crossQuartz glass
strip with notches
Diameter of Sensor
Pt Wire

0.07 mm (0.003 in)

0.4 mm (0.016 in)
Protective SheathQuartz glass, Diameter: 7 mm (0.28 in), Length: 520 mm (20.5 in)Quartz glass, Diameter: 7 mm (0.28 in), Length: 680 mm (26.8 in)

The official maximum temperature of an SPRT as a defining interpolation instrument of the ITS-90 is 961.78 °C, but these types of SPRTs were found to be stable up to at least 1070 °C. The annealing temperature during the stability test was 1085 °C. The lower temperature limit of these types of SPRTs can be as low as –200 °C.
In general, it is suggested that a 25-ohm SPRT be used below 0 °C.5681/ 5683/ 5684

5681/ 5683/ 5684

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