Thermocouple IDIQ sole_source_justification_MFR Signed _Redacted.pdf

Sole Source (Including Brand Name) Justification - Simplified Procedures for Certain Commercial Items

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This is a justification for other than full and open competition. AFTC/PZIA (Arnold) is the contracting agency and organizational activity responsible for this proposed contract action. The Contracting Officer (CO) is Robert Mosley.

The Government is in need of coaxial thermocouples to support mission essential activities in the AEDC Hypervelocity Wind Tunnel 9, White Oak, MD., and the only capable manufacturer to execute this IDIQ contract is Medtherm Corporation, 2604 Newby Rd SW, Huntsville, AL, 35805. The thermocouples are required to analyze heat transfer measurements to support hypersonic testing programs vital to the U.S. National Defense.

The procurement will be a firm-fixed priced five-year IDIQ contract with an anticipated award date no later than 30 October 2025. Certified funds for the initial delivery order are available under PR number F1EGDT5148A001.

The estimated ceiling for this IDIQ is

This is a follow-on to contract FA9101-23-D-B001 for the procurement of the following thermocouple models:

TCS-E-061-0.375-60-10370, TCS-E-031-0.375-96-10936, and TCS-E-061-0.500-96-10370 due to their ability to meet the agency's needs by achieving the mandatory requirements listed below:

- NIST-traceable Type-E, Chromel-Constantan thermocouple materials (outer sheath Chromel and inner pin Constantan)

- Outer sensor cylinder diameters of 0.061” and 0.031”

- Sensor length options of 0.375” and 0.5” or longer

- The sensor length may be trimmed down for installation in thinner walls or to fit into limited internal volume of the model without adverse effects to sensor operation

- Sensor shall be installed into test article using adhesives such as Loctite #271 or #620

- Sensor shall be contoured to outer-mold-lines of a test article after adhesive fully cured

- Thermocouple junction at the outer surface of the model created by abrasion (file and/or sandpaper)

- Fast response time to metal wall surface temperature changes, typically in the order of microseconds

- Transition from coaxial thermocouple body to lead wires to occur close to body, approximately 0.15" or less”

- Any strain relief applied between the coaxial thermocouple body and lead wires cannot be larger than the cylindrical diameter of the coaxial thermocouple body

- Lead wires from coaxial thermocouple assembly to be provided as Type-E thermocouple wire. Lead wires should be no larger than 30 AWG Teflon insulated solid wires

These minimum requirements were developed during an experiment conducted in the AEDC Aerothermal Measurements Laboratory which involved applying a uniform heat flux using a radiative heat source lamp bank to sample coaxial plug assemblies installed in a test sample plate alongside National Institute of Standards and Technology (NIST) traceable Schmidt-Boelter-style heat flux standards.

The anticipated CLIN structure for this procurement is:

CLIN 0001 TCS-E-061-0.375-60-10370; estimated quantity of units per year: units total CLIN 0002 TCS-E-031-0.375-96-10936; estimated quantity of units per year: units total CLIN 0003 TCS-E-061-0.500-96-10370; estimated quantity of units per year: units total

Estimated five-year contract value:

It is anticipated that a single Indefinite Delivery Indefinite Quantity (IDIQ) Contract will be awarded utilizing FAR subpart 13.5 procedures in conjunction with FAR Part 12 procedures.

Sole Source (Including Brand Name) Justification - Simplified Procedures for Certain Commercial Items

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10 USC 3204(a)(1), Only One Responsible Source - No Other Supplies or Services Will Satisfy Agency Requirements

Medtherm Corporation is the only vendor who has the ability to provide coaxial thermocouples that can meet the mandatory requirements detailed in section III. Models TCS-E-061-0.375-60-10370, TCS- E-031-0.375-96-10936 and TCS-E-061-0.500-96-10370 achieve the project's mandatory requirements, with the only differences between each different sensor model being:

- outer sensor cylinder diameter

- sensor length

- epoxy potted AWG Chromel/Constantan solid thermocouple wire

- epoxy transition from sensor to wire

By meeting the requirements detailed in section III, Medtherm Corporation demonstrates their unique qualifications by proving they are the only vendor that has the ability to provide a highly durable Type-E, Chromel-Constantan, thermocouple with fast-response times and with the ability for the thermocouple to be contoured to the outer mold lines of a test article.

The importance of these unique characteristics is described below.

Medtherm Corporation's three coaxial thermocouple models are made of two dissimilar metals joined together at one end so that when the junction is heated or cooled, a voltage is created that can be correlated to temperature rise and then to heat flux at the thermocouple location, which makes the sensor design inherently durable. Medtherm sensors also feature epoxy potted Teflon insulated lead wire construction that is durable yet allows for transition from sensor body to lead wire to occur close to the body, at 0.15” or less. This is required due to limited internal volume inside the wind tunnel test articles.

A response time of 10 microseconds or less is required to resolve the heat flux changes as the wind tunnel test article is being dynamically pitched at up to 80 deg/sec during a Tunnel 9 wind tunnel run. The response time of the Medtherm coaxial thermocouples junction is ~10 microseconds. Medtherm is the only vendor to date that can meet the response time requirement.

The models tested in Tunnel 9 are typically very complex 3-dimensional geometries representative of flight vehicles being developed by the customers. It is important for any sensor used in a test article to not disturb the outer mold lines of the model as this may alter the flow around the test article and thus invalidate the experiment. For this reason, the ability to contour the thermocouples to the outer mold lines of a complex test article is required.

The technique to derive the heat flux from coaxial thermocouple sensors is extremely sensitive to many physical factors including material thermal properties, installation techniques, data acquisition techniques, and multidimensional heating issues. AEDC has conducted an experiment in the AEDC Aerothermal Measurements Laboratory which involved applying a uniform heat flux using a radiative heat source lamp bank to sample coaxial plug assemblies installed in a test sample plate alongside NIST traceable Schmidt-Boelter-style heat flux standards. Test samples included Medtherm coaxial thermocouples installed in 17-4 and 15-5 stainless steel plugs. The data from the thermocouples were sampled and processed in a way consistent with Tunnel 9 test practices and the process was optimized based on the agreement with the NIST-traceable standard. A complete description of the experiment can be found in the official contract file element 135, Initial Memorandum and Preliminary Documents, document title: Aerothermal Measurement Improvements using Coaxial Thermocouples at

Sole Source (Including Brand Name) Justification - Simplified Procedures for Certain Commercial Items

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These sensors are installed by gluing into a tight fitting hole in a stainless steel substrate. The idea is to have the installation as seamless with the substrate as possible. The senor is contoured to match outer mold line by sanding the top surface of the sensor, and this also forms the junction. The sensors can be used for many tests while they are in the substrate, but they cannot be extracted to be re-used in a different test article. Tunnel 9 is willing to purchase and evaluate samples produced by a new vendor and consider them for future contracts if the sensors perform as specified. It is crucial for Tunnel 9 to have proven sensors for this IDIQ as they are used for customer testing and Tunnel 9 cannot put critical customer data at risk. At the present, only one vendor (Medtherm) has a proven capability to manufacture these sensors.