Glass-encapsulated thermistor 5640 Series

for ambient temperature measurement

Product overview
Each temperature thermistor probe contains an ultra-stable glass thermistor sealed inside a thin-wall stainless steel tube. The thermistor bead is formed from manganese, nickel and cobalt oxides mounted on 0.1 mm platinum leads. For long-term stability the thermistor is aged at multiple temperatures for 16 weeks and probe stability is verified during the aging process to meet published specifications.

Performance and use
The 5640, 5641 and 5642 models are specified for 0 °C to 60 °C; the 5643 and 5644 models cover 0 °C to 100 °C. Stability is either ±0.002 °C or ±0.005 °C depending on model and is guaranteed for one year. Each probe is supplied with a precision calibration traceable to NIST and a computer-generated table in 0.01 °C increments based on a fitted resistance–temperature formula.

Key features

• 5640, 5641 and 5642: temperature range 0 °C to 60 °C.
• 5643 and 5644: temperature range 0 °C to 100 °C.
• Stability: either ±0.002 °C or ±0.005 °C (model dependent).
• Manufacturer accuracy to ±0.001 °C in the 0 °C to 60 °C interval for applicable models.
• System accuracy of ±0.004 °C or better when used with an appropriate high-resolution readout (example: Black Stack 1560 thermometer).
• Each probe supplied with NIST-traceable manufacturer calibration and a calibration report with a 0.01 °C step table.

Calibration formula and points
Resistance–temperature relationship used: R = exp(A + B/T + C/T2 + D/T3). Calibration points for 0 °C to 60 °C: triple point of water (0.01 °C), 15 °C, 25 °C, 30 °C, 37 °C, 50 °C and 60 °C. For 0 °C to 100 °C models additional points at 80 °C and 100 °C are used.

Application notes
These thermistor standards are precision, rugged temperature sensors intended for use as secondary or working temperature standards in laboratory metrology and demanding field environments. They are generally resistant to shock and vibration. When paired with a compatible high-resolution readout (for example the Black Stack 1560), the combination can provide 0.0001 ° resolution and total system accuracy better than ±0.004 °C.

Technical specifications

• 5640 — Diameter x Length: 6.35 x 229 mm (0.25 x 9 in); Range: 0 °C–60 °C; Drift: ±0.005 °C/yr; Manufacturer accuracy (0–60 °C): ±0.0015 °C; Manufacturer accuracy (60–100 °C): n/a; Wires: 4; Nominal resistance at 25 °C: 4.4 kΩ.
• 5641 — Diameter x Length: 3.18 x 114 mm (0.125 x 4.5 in); Range: 0 °C–60 °C; Drift: ±0.002 °C/yr; Manufacturer accuracy (0–60 °C): ±0.001 °C; Manufacturer accuracy (60–100 °C): n/a; Wires: 4; Nominal resistance at 25 °C: 5 kΩ.
• 5642 — Diameter x Length: 3.18 x 229 mm (0.125 x 9 in); Range: 0 °C–60 °C; Drift: ±0.002 °C/yr; Manufacturer accuracy (0–60 °C): ±0.001 °C; Manufacturer accuracy (60–100 °C): n/a; Wires: 4; Nominal resistance at 25 °C: 4 kΩ.
• 5643 — Diameter x Length: 3.18 x 114 mm (0.125 x 4.5 in); Range: 0 °C–100 °C; Drift: ±0.005 °C/yr; Manufacturer accuracy (0–60 °C): ±0.0015 °C; Manufacturer accuracy (60–100 °C): ±0.0025 °C; Wires: 4; Nominal resistance at 25 °C: 7.5 kΩ.
• 5644 — Diameter x Length: 3.18 x 229 mm (0.125 x 9 in); Range: 0 °C–100 °C; Drift: ±0.005 °C/yr; Manufacturer accuracy (0–60 °C): ±0.0015 °C; Manufacturer accuracy (60–100 °C): ±0.0025 °C; Wires: 4; Nominal resistance at 25 °C: 7.5 kΩ.
• Note: Manufacturer accuracy does not include long-term drift; resistance traceability adds an additional uncertainty of approximately ±0.0025%.