The Fluke Hart Scientific 5611T is a Teflon-coated secondary reference thermistor probe designed for high-accuracy temperature measurement across a narrow temperature range. The probe combines a thermistor bead encapsulated in a mylar sleeve inside a Teflon sleeve, with the Teflon sleeve melted around the Teflon-insulated cable to form a moisture-proof seal. This construction makes the 5611T suitable for measurements in liquids and a variety of environments where chemical resistance and immersibility are required.

The 5611T is used for accurate temperature work across a narrow temperature range from 0 °C to 100 °C. The Teflon coating makes it impervious to most liquids, supporting applications including bio-pharmaceuticals as referenced on the datasheet. The probe is immersible to nearly 6 meters (20 ft) and is flexible enough to be rolled up in the hand. Its small sensing element minimizes self-heating, which makes measurements in air more accurate than those obtained with a PRT, and its compact size enables faster response without requiring as much immersion depth as a PRT.

ValueTronics International stocks, inspects, and ships precision thermometry instruments such as the 5611T from our 20,000 square foot secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. Operating since 1992, our facility serves calibration laboratories, pharmaceutical manufacturers, and metrology professionals who require not only the correct instrument but verifiable handling and documentation. Unlike pass-through brokers and drop-shippers, we physically handle every probe through our Elgin operation, which is the difference between a transaction and a measurement asset entering your calibration program with a known chain of custody.

Brand Heritage

Hart Scientific was a US-based precision thermometry instrument manufacturer founded in American Fork, Utah, and was acquired by Fluke Corporation. Probes and instruments originally branded Hart Scientific are now produced under the Fluke Calibration banner, with the Hart Scientific name retained on much of the legacy thermometry product line. References to Hart Scientific on this product reflect that lineage rather than a separate active company.

Compare Other Models in This Series

The 5611T is part of Hart Scientific's Secondary Reference Series of thermistor probes, designed for high-accuracy thermometry standards work across a narrow temperature range. Within this family, the 5611T occupies the Teflon-coated configuration, distinguished from sheathed probes in the series by its flexibility, chemical resistance, and suitability for immersion in liquids.

Probes in the Secondary Reference Series share the common attributes of small sensing elements, low self-heating, and short-term accuracy to ±0.01 °C with NIST-traceable calibration. The 5611T applies these characteristics to applications where Teflon construction is required, including environments incompatible with metal-sheathed probes.

Each new 5611T configuration listed below is its own product page with condition-matched pricing and documentation. Termination type is specified at order time and is reflected in the product line item rather than as a separate condition tier.

The 5611T is differentiated within the Secondary Reference Series by its Teflon sheath and moisture-proof construction. The thermistor bead is encapsulated in a mylar sleeve inside a Teflon sleeve, with the Teflon sleeve melted around the Teflon-insulated cable. This construction allows immersion to approximately 6 meters and provides chemical resistance to a wide range of liquids, including applications such as bio-pharmaceuticals referenced in the datasheet.

Within the family, configurations differ by termination type — bare wire, 5-pin DIN for Tweener thermometers, gold pins, INFO-CON for 1521 or 1522 handheld thermometers, banana plugs, mini spade lugs, mini banana plugs, and spade lugs. The termination chosen must match the intended readout instrument from the Hart Scientific lineup.

Calibration options also differentiate the family. Standard configurations ship with NIST-traceable calibration accurate to ±0.01 °C, with the R vs. T table and interpolation equation furnished. Optional NVLAP-accredited calibration adds documentation at six points over the 100 °C span and compliance with NCSL/ISO/IEC 17025:2000 and ANSI/NCSL Z540-1-1994, available as a single-probe calibration (1925-A) or as a system calibration combined with the readout (1935-A).

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Product Core & Specifications

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.