Resistance temperature sensor 5698-25

RTDplatinum resistiveimmersion

Product overview
The Fluke 5698-25 Working Standard Platinum Resistance Thermometer (SPRT) is engineered for calibration laboratories and industrial metrology facilities that require ITS-90 traceability and stable long-term performance. It serves as a transfer standard for bringing national-lab traceability into working labs and for supporting routine and critical temperature measurements.

Key features

• Meets ITS-90 SPRT guidelines and full resistance-ratio requirements for SPRTs.
• Typical long-term drift < 0.003 °C; specified long-term drift below 6 mK.
• Calibration options: fixed-point or delivered without calibration.
• 485 mm fused silica (quartz) protective sheath covering -200 °C to 670 °C.
• Nominal 25-ohm design (R_TPW ≈ 25.5 Ω ±0.5 Ω) with 1.0 mA excitation current for standard readouts.
• Strain-free platinum sensing element mounted on a fused silica cross frame; annealed and tested for stability.
• Sealed construction with convection-prevention discs and gold-plated terminations for reliable connections.

Designed as a working standard

• Intended to transfer ITS-90 from national or standards laboratories to user facilities.
• Suitable for both standards transfer and routine calibration tasks in busy calibration environments.

Transparent performance and support

• Full performance specifications published to set clear expectations for instrument behavior.
• Calibrations performed in Fluke accredited laboratories using fixed-point or comparison methods to provide ITS-90 traceability.

Specifications
Temperature range: -200 °C to 670 °C
Nominal R_TPW: 25.5 Ω (± 0.5 Ω)
Operating current: 1.0 mA
Resistance ratios: W(234.315 K) ≤ 0.844235; W(302.9146 K) ≥ 1.11807
Sensitivity: 0.1 Ω/°C
Drift rate: < 0.006 °C/100 hours at max temperature (typically < 0.003 °C)
Self-heating at TPW: < 0.002 °C under 1 mA
Reproducibility: ± 0.0015 °C or better
R_TPW drift after thermal cycling: < 0.001 °C
Pt sensor wire diameter: 0.07 mm (0.003 in)
Protective sheath: quartz glass, diameter 7 mm, length 485 mm
Lead wires: four sensor wires

Technical specifications

• Temperature range: -200 °C to 670 °C
• Nominal resistance at TPW: 25.5 Ω (± 0.5 Ω)
• Operating current: 1.0 mA
• Resistance ratios: W(234.315 K) ≤ 0.844235; W(302.9146 K) ≥ 1.11807
• Sensitivity: 0.1 Ω/°C
• Drift rate: < 0.006 °C/100 hours at max temperature (typically < 0.003 °C)
• Self-heating at TPW: < 0.002 °C under 1 mA
• Reproducibility: ± 0.0015 °C or better
• Drift after thermal cycling: < 0.001 °C
• Pt sensor wire diameter: 0.07 mm (0.003 in)
• Protective sheath: quartz glass, 7 mm diameter, 485 mm length
• Lead wires: four sensor wires