5686-B Glass Capsule SPRT

Precision, Stability, and Reliability for Extreme Temperature Measurement

Primary Standard SPRT for Cryogenic and Immersion Applications

The Fluke 5686-B Glass Capsule Standard Platinum Resistance Thermometer (SPRT) is designed as a primary standard instrument for converting temperature to resistance with uncompromising accuracy. Fully compliant with ITS-90, the 5686-B is part of the trusted Fluke Calibration SPRT family, delivering outstanding performance in both laboratory and demanding field environments.

Key Features and Specifications

• ITS-90 Compliance – The 5686-B meets the requirements of the International Temperature Scale of 1990 (ITS-90), with resistance ratios:
  • W(302.9146 K) ≥ 1.11807
  • W(234.3156 K) ≤ 0.844235
• Exceptional Temperature Range – Covers –260 °C (13 K) to 232 °C (505 K), making it ideal for cryogenic applications and high-precision temperature measurement across a wide spectrum.
• Compact Design – With a diameter of just 5.8 mm and a length of 56 mm, the 5686-B is well-suited for applications requiring a totally immersed probe or where space is limited.
• Fixed-Point Calibration Ready – Fixed-point calibrations are available from –200 °C to 232 °C, ensuring accuracy for critical measurement points.
• Superior Construction – The sensing element is made from high-purity platinum wire wound strain-free on a fused silica cross frame, and the special glass capsule is pressure-sealed with 5N pure helium to maintain integrity and performance.

Designed for Demanding Measurement Environments

• Low Temperature Excellence – Engineered for operation down to 13 K (–260 °C), the 5686-B is the standard of choice for cryogenic temperature measurement.
• Minimized Heat Flow – The glass capsule design supports full immersion, reducing heat flow from or to the sensor and improving measurement stability.
• Alternative to Long-Stem SPRTs – When traditional long-stem SPRTs are not suitable, the compact 5686-B Glass Capsule SPRT fits into vessels and setups where complete encasement is needed.
• Proven Reproducibility, Reliability, and Stability – Each thermometer is carefully annealed and tested for stability, delivering consistent, accurate results in both standard and challenging scenarios.

Why Choose the Fluke 5686-B Glass Capsule SPRT?

• Wide temperature coverage for both cryogenic and calibration applications
• Compact, fully immersible probe design for versatile use
• High-purity platinum element and strain-free construction for unmatched stability
• Pressure-sealed capsule maintains sensor protection and performance
• Meets rigorous international standards (ITS-90) for trustworthy measurement

For laboratories and industries where precise, stable, and reproducible temperature measurement is essential, the Fluke 5686-B Glass Capsule SPRT sets the benchmark for performance and reliability.