Hart 5640 Thermistor Standards Specifications

	*Model 5640 to 5644 Thermistor Standards Specifications*
	*Hart Scientific Calibration Products > Thermometer Probes Secondary Standards >*
	Model 5640-5644 Features > Specifications > Ordering Information >


	Models 5640 to 5644 Thermistor Standards Probe - Specifications

Model	Dimensions	Range	Drift °C/Year	Accuracy* 0°C to 60°C	Accuracy* 60°C to 100°C	Wires	Nominal Resistance at 25°C
5640	229mm x 6.35mm	0°C to 60°	±0.005°C	±0.0015°C	n/a	4	4.4kΩ
5641	114mm x 3.18mm	0°C to 60°	±0.002°C	±0.001°C	n/a	4	5kΩ
5642	229mm x 3.18mm	0°C to 60°	±0.002°C	±0.001°C	n/a	4	4kΩ
5643	114mm x 3.18mm	0°C to 100°	±0.005°C	±0.0015°C	±0.0025°C	4	10kΩ
5644	229mm x 3.18mm	0°C to 100°	±0.005°C	±0.0015°C	±0.0025°C	4	10kΩ

Note* Does not include long-term drift, resistance traceability adds additional ±0.0025%

Thermistors make great Reference Thermometers!

Contrary to some traditional belief, reference-grade thermistors do indeed make great temperature standards.
Consider:

Stability. Today's glass-encapsulated thermistors are well sealed to prevent sensor oxidation and drift. In fact standards-level thermistors usually won't drift more than a few milli-degrees in a year.
Accuracy. Thermistors are easier (than PRTs) to read accurately because of their larger base resistance and large change in resistance-per-degree. It's common to get meaningful and repeatable readings from a thermistor with resolution of 0.0001°C.
Durability. While a bare thermistor bead can be fairly delicate, a properly constructed stainless steel-sheathed thermistor probe can be more rugged than PRT or SPRT.

For about the same cost of a secondary level PRT, you can buy a well calibrated standards thermistor probe with accuracy and stability that rivals an SPRT. You can also save wear and tear on your SPRT by using a thermistor over the 0°C to 100°C temperature range.