Thermometry Bridge System

Announcement Type: Special Notice

Classification Code: 6695

Announcement Number: NB685000-25-02257

Subject: Notice of Intent to Noncompetitively Acquire Thermometry Bridge System

The National Institute of Standards and Technology (NIST) Dimensional Metrology Group (DMG) delivers world class dimensional calibration services to support United States manufacturing and other industries. Precise temperature measurement is necessary to correct changes in the wavelength of light in air in our interferometer systems, as well as correct for changes in thermal expansion of gages under test. The NIST DMG is seeking a new thermometry bridge system to both replace ageing equipment and transfer the temperature scale from NIST calibrated thermometers to the secondary thermometers used across our various measurement services.

The NIST DMG is seeking one thermometry bridge system that includes one resistance thermometry bridge and one separate expansion unit with additional measurement channels. The system will be integrated into a length interferometer and serve double duty as a standard against which to calibrate secondary thermometers inside a temperature bath. Separating the main thermometry bridge unit and the expansion unit allows the bridge to be removed and sent for calibration without disrupting all the probe connections in the interferometer system.

This notice is not a request for a quotation. A solicitation document will not be issued and quotations will not be requested.

This acquisition is being conducted under the authority of FAR 13.106-1(b) via FAR 13.106-1(b). The North American Industry Classification System (NAICS) code for this acquisition is 334516, Analytical Laboratory Instrument Manufacturing.

The NIST DMG requires a precision thermometry bridge for our dimensional measurement services in order to meet the research and calibration needs of our group. Specifically, we require a thermometry bridge that: 1) provides precision temperature measurement using resistance sensors (thermistors, platinum resistance thermometers, and standard platinum resistance thermometers); 2) comes in two units—a main unit and an expansion unit—that support numerous individual sensors and can be expanded to accommodate future needs; 3) stores key properties of the sensors in persistent, internal memory; 4) easily integrates into existing, in-house written Python code; and 5) operates silently in ambient conditions encountered in NIST laboratories. After thorough evaluation, it has been determined that the thermometry bridge system from manufacturer, Isotech North America, Inc., is essential for several reasons:

1. Compatibility: The NIST DMG already has an Isotech microK thermometry bridge for its gage block interferometry calibration services. Those services share custom developed software with our sphere diameter measurement service, where this thermometry bridge will be used. Developing and validating entirely new code to interface a different model of thermometry bridge to our measurement software is a large undertaking that would require many hours of labor from NIST’s laboratory staff. Further, by maintaining just one code base for two services, NIST can significantly reduce the ongoing cost of maintenance.


2. Technical: In addition to supporting the NIST DMG sphere diameter interferometry measurement service, this unit will serve double duty as a transfer standard from NIST primary temperature calibration to NIST DMG secondary thermometers. This requires the unit be easily removable without disturbing the existing connections to sensors. A system consisting of one main unit and one expansion unit satisfies this need. Isotech’s thermometry bridge system is unique in its upper limit of measurement channels without losing measurement performance. Many measurement channels are essential for ongoing research mapping spatial gradients of the air, instrument, and artifact temperatures. Without the ability to have this expanded measurement channel ability, it would ultimately drive measurement uncertainty and limit NIST’s ability to provide best-in-world calibration of sphere diameter, which supports both external and internal customers. Additionally, this thermometry bridge will be used to support calibration services housed in a highly temperature-stabilized laboratory. The laboratory is set up in a control room/instrument room configuration and great effort is taken to locate sources of heat (especially electronics) in the control room and away from the instrument room. Consequently, equipment in the control room needs to run silently for the sake of human occupants. No other manufacturer offers a completely silent system. Additionally, Isotech does not have any authorized resellers.

NIST conducted market research from May 2025 – July 2025 by internet searches, discussions with sources, and a sources sought posting. Sources sought NIST-SS25-62 was posted from June 24, 2025, through July 2, 2025. No responses were received. The results of that market research revealed that only Isotech North America, Inc.,158 BRENTWOOD 4, COLCHESTER, VT 05446 USA, UEI: MJV6CBAU3N98 appears to be capable of meeting NIST’s requirements.

However, any sources that believe they are capable of meeting NIST’s minimum requirements are encouraged to respond to this notice by the response date to provide the following information at a minimum: Company Unique Entity Identifier number in https://sam.gov; details about what your company is capable of providing that meets or exceeds NIST’s minimum requirements; whether your company is an authorized reseller of the product or service being cited and evidence of such authorization; and any other information that can help NIST determine whether this requirement may be competitively satisfied.