From Concept Sketch to Serial Production
A catalog sensor solves the average measurement problem. Most of the measurement problems our customers bring us are not average. A turbine engineer needs to measure the rim-cavity temperature of a high-pressure stage at 980 °C with a sensor that survives 50 g vibration. A semiconductor process engineer needs a wafer-thin RTD that fits inside a 1 mm gap and reaches steady state in under a second. A cryogenic propellant team needs a probe that maintains accuracy at the boiling point of liquid hydrogen.
Thermometrics Corporation has been engineering and manufacturing custom temperature sensors since 1965. Our application engineers, materials specialists, and manufacturing engineers work alongside the customer's design team from the first concept review through prototype, qualification, and serial production. Because the same engineers who designed the part oversee its manufacture, the part that ships in production is the part that was qualified — not a re-interpreted derivative.
We engineer to your specification, to industry standards, or to a clean-sheet concept. We hold no minimum order quantity for engineering work. The same Northridge facility that runs serial production handles one-off prototype builds, with no transfer of tribal knowledge required when you scale.
- Application engineering for any temperature measurement problem
- Concept-to-production single-vendor accountability
- Mechanical, electrical, and materials engineering in-house
- AS9100D and ISO 9001:2015 quality system applied from prototype forward
- No minimum order quantity for engineering and prototype work
- Source-controlled drawings and dedicated part numbers for production
One Vendor, One Quality System
The engineering team that scopes your sensor sits down the hall from the technicians who will weld, swage, and pot it. Drawings, route sheets, and inspection records share the same revision-controlled document repository — eliminating the failure mode where a prototype that passed qualification cannot be reproduced in production because tribal knowledge never made the trip from engineering to the floor.
Engineering Inputs We Need
Required: Operating temperature range, accuracy target, sensor envelope, environment (pressure, vibration, atmosphere)
Helpful: Existing drawings, mating connector P/N, certification targets, EAU and production roadmap, calibration program
Optional: CAD model of mounting feature, FEA expectations, prior failure modes
What We Engineer Routinely
The capability summary below reflects work we do regularly, not occasionally. If you do not see your application here, ask anyway — most of the truly unusual sensors in our portfolio were unprecedented when they were first quoted.
Non-Standard Geometries
Bent probes, multi-junction assemblies, surface-contact and skin-temperature designs, miniature bore probes (down to 0.50 mm OD), and large-diameter immersion probes (up to 25 mm OD). Custom sheath lengths up to 12 m for tall vessels and reactor cores.
Specialized Alloys
304/316 stainless for routine industrial work; 321 SS for high-temperature exhaust; Inconel 600 and 625 for oxidation resistance above 870 °C; Hastelloy C-276 for severe chemical service; tantalum for hydrochloric acid; platinum sheathing for laboratory-grade ultra-clean processes; high-purity alumina ceramic for furnace and refractory applications.
Hybrid RTD / Thermocouple Assemblies
Multi-element assemblies that combine a high-accuracy PT100 RTD with one or more thermocouples in a single sheath — for redundant measurement, primary/backup architectures, or simultaneous slow- and fast-response sensing on the same physical probe. Routed to a single connector or split for separate cold-junction handling.
MIL-Spec Connectors & Terminations
MIL-DTL-38999 series III circular connectors, MIL-DTL-26482 connectors, MIL-DTL-83723 connectors, hermetic glass-to-metal terminations, EMI/RFI backshells, MIL-W-22759 and MIL-W-25038 wire, ITAR-controlled and AS22759 high-temperature insulation systems. Crimp inspection per IPC/WHMA-A-620.
Hermetic & Pressure-Rated Seals
Glass-to-metal seals tested to 10⁻⁹ atm·cc/s helium leak rate; brazed cone-and-thread fittings to 60,000 psi for hydrogen and supercritical service; metal-C ring seals for vacuum and gas-tight applications; epoxy potting for low-cost industrial moisture sealing.
Hazardous-Area Designs
Intrinsically safe and explosion-proof sensor designs compatible with FM, CSA, and ATEX certification programs. Encapsulation, flame paths, and fault-tolerant assembly compatible with Class I Div 1 and Zone 0 / 1 hazardous-area installations.
DFM Is the Engineering Conversation We Want to Have Early
A sensor that performs brilliantly on the bench but cannot be reproduced at scale is an engineering exercise, not a product. Design-for-Manufacturing review is woven into every step of our design process. Our manufacturing engineers participate in the design review, not only in the post-design hand-off. The result is a sensor whose tolerances reflect what we can actually hold, whose materials are sourced from qualified suppliers we already have a relationship with, and whose assembly sequence has been mentally walked through a working cell before drawings are released.
DFM is most valuable for the customer who is bringing a new measurement problem to silicon. Even an experienced design house benefits from a manufacturing review — the questions we ask routinely surface unstated assumptions about tolerance stack-up, weld accessibility, calibration immersion depth, and end-of-line test fixturing. We share the DFM report with every prototype build.
Six Steps From Concept to Production
The process below is the path every custom Thermometrics sensor follows. The cadence varies — a derivative of an existing design moves through phases 1–3 in days; a clean-sheet aerospace qualification can take twelve to eighteen months. The phase gates do not change.
Requirements Review
Joint kick-off with the customer's engineering team. Operating envelope (temperature, pressure, vibration, atmosphere) confirmed in writing. Accuracy target, response-time target, and lifetime expectation captured. Mating mechanical and electrical interfaces frozen. Failure modes from prior designs (if any) reviewed. A signed Statement of Work documents the inputs for the rest of the program.
Conceptual Design
Two or three candidate architectures are sketched against the requirement set. Trade-offs in sensor type (RTD versus thermocouple versus hybrid), sheath material, junction geometry, lead routing, and termination are evaluated. A concept-selection review with the customer selects one path forward and identifies what would have to change for the alternatives to be viable later.
Detailed Engineering
Source-controlled drawings produced to ASME Y14.5 GD&T. Material call-outs with full DFAR and REACH compliance tracking. Bill of materials with revision-controlled part numbers. FMEA performed where required. Drawing package issued for prototype build with formal revision history. Customer reviews and signs the package before any metal is cut.
Prototype Build & First Article
Prototype units fabricated in the same manufacturing cell that will later run production — not in a separate engineering shop. First Article Inspection performed to AS9102 with FAIR documentation. Functional test at room temperature, ice point, and one or two characteristic process temperatures. Photos and inspection records sent with the units. Customer receives parts to evaluate in their own test bench.
Qualification Testing
Environmental qualification per the program's requirements — thermal cycling, vibration, pressure, salt spray, EMI, leak rate, dielectric withstand, and burn-in as applicable. Tests performed in our in-house qualification laboratory or witnessed at an accredited third party. Acceptance Test Procedure (ATP) signed off by both parties. Qualification report serves as the design-freeze authorization for production.
Production Release
Drawing package and work instructions promoted from prototype to production status under our QMS. Cell layout, fixturing, and end-of-line test re-validated at production rate. PPAP-equivalent submission for automotive customers; First Article and AS9100 documentation package for aerospace. Ongoing supply with calibration, traceability, and certification at every shipment.
Sheath, Sleeve & Wire Materials
The material selected for the wetted surface of a temperature sensor is the dominant determinant of its service life. Below is a summary of the sheath, sleeve, and structural materials our engineering team works with routinely. For every material we maintain qualified domestic suppliers, full mill-test traceability, and the documented experience to specify wall thickness, surface finish, and post-fabrication processing appropriate to the application.
304 / 316 Stainless Steel
The everyday workhorses. 304 for general-purpose service to 870 °C; 316 with its molybdenum addition for improved pitting and crevice corrosion resistance in chloride and mildly acidic environments. Sanitary 316L (low carbon) for ASME BPE pharmaceutical work.
Inconel 600 / 625
Nickel-chromium superalloys with outstanding oxidation and high-temperature creep resistance. Inconel 600 to 1100 °C continuous; Inconel 625 adds molybdenum and niobium for improved chloride and acid resistance in aggressive high-temperature streams. Standard sheath for furnace, turbine, and reactor applications.
Hastelloy C-276
Nickel-molybdenum-chromium superalloy with very high resistance to a wide range of wet chemical environments, including hypochlorite, hot concentrated chloride solutions, sulfuric and phosphoric acids. The default selection for chemical-process and chlor-alkali sensors.
Tantalum
Refractory metal essentially inert to hydrochloric acid at all concentrations and to most acidic halide environments below 150 °C. The selection of last resort for measurement points in HCl strippers, halide reactors, and certain pharmaceutical and electrochemical processes.
Platinum & Pt-Rh Sheath
For ultra-clean process and laboratory applications where stainless or nickel contamination is unacceptable — semiconductor, certain pharmaceutical drying processes, primary calibration laboratories. Platinum-rhodium structural alloys for high-temperature laboratory furnace probes.
High-Purity Alumina (Al₂O₃)
99.7%-purity ceramic sheath for service above the upper temperature limit of metallic sheaths — up to 1700 °C in oxidizing atmospheres. Single-, dual-, and four-bore configurations for noble-metal thermocouple insulation in glass, ceramic, and refractory processes.
321 Stainless Steel
Titanium-stabilized austenitic grade that resists intergranular corrosion (sensitization) after welding in service from 425–815 °C. Preferred sheath material for aerospace exhaust gas temperature (EGT) probes and high-temperature jacketed cable assemblies.
Titanium, Monel, Zirconium
Titanium for seawater and certain biocompatible probes; Monel 400 for hydrofluoric acid service; zirconium for nuclear-grade and certain aggressive process applications. Available on request — supplier-qualified and mill-traceable.
Designed for the Real Environment
The temperature is rarely the only environmental challenge. The cases below summarize the secondary stressors we routinely design around — each shifts the choice of element, sheath, lead, seal, and termination in a different direction.
Cryogenic
Liquid nitrogen (-196 °C), liquid hydrogen (-253 °C), and liquid helium (-269 °C) service. Specialized assembly techniques to minimize thermal-contraction stress on the platinum element, low-thermal-mass tip designs for fast response, and helium-leak-tight glass-to-metal seals where vacuum integrity is required.
High Temperature
Continuous service above 1000 °C: noble-metal thermocouple types (R, S, B), high-purity alumina sheathing, refractory-metal terminations, and consideration of preferential-oxidation effects on noble elements. Custom designs to 1700 °C in oxidizing service.
High Pressure
Cone-and-thread fittings and pressure-balanced compression fittings rated to 60,000 psi. Internal stress analysis of sheath wall thickness against external pressure, with finite-element validation where required. Common for hydrogen and supercritical-fluid sensors and downhole oil-and-gas instrumentation.
Corrosive Atmosphere
Material selection for HCl, H₂SO₄, HF, hypochlorite, hot caustic, and chlor-alkali process streams. Where stainless and Inconel are not viable, tantalum and zirconium sheathing complete the option set. Sacrificial-thermowell architectures considered where periodic replacement is acceptable.
Vibration & Mechanical Shock
Engine, turbomachinery, and launch-vehicle applications routinely demand qualification to 50 g random vibration and shock pulses in the kilo-g range. Design considerations include element bonding technique, lead-wire routing inside the sheath, swage-vs-MgO insulation density trade-offs, and termination strain relief.
Radiation & Nuclear
Reactor-grade RTDs and thermocouples for inside-containment service. Material selection limited to radiation-qualified alloys; insulation chosen for low neutron cross-section. Hermetic seals tested for long-term integrity under thermal cycling and radiation flux.
A Partnership, Not an RFQ Transaction
Most custom-sensor failures we are asked to investigate trace back not to a manufacturing defect but to a missed conversation early in the design phase — an unstated assumption about installation orientation, a poorly characterized vibration profile, a connector that the customer's wire-harness vendor changed after the sensor design was frozen. The remedy is communication cadence.
Our default engagement model is to assign a single application engineer to your program who participates in your design reviews, attends your test campaigns when invited, and is the named point of contact for technical questions for the program's life. That engineer is supported by manufacturing, materials, and metrology specialists internally, but to you they are one person.
We are comfortable working under your NDA, your contractor agreement, your DPAS-rated PO, and your ITAR program — and we hold ourselves to the same documentation discipline whether the work is for an R&D laboratory or for a Department of Defense prime.
The First Conversation Is Free
We do not bill for the application-engineering call that determines whether your problem is one we should quote. Bring us a problem statement; we will tell you within a few business days whether it falls within our capability envelope, what the engineering uncertainties are, and what a representative budget and schedule look like.
- NDA in place within one business day
- Joint kick-off call scheduled inside one week
- Quote with engineering scope, milestones, and pricing inside two weeks
- Single named application engineer for the program's life
- Production-rate cell already exists for ramp without re-engineering
From Conversation to Hardware in Hand
The lead times below summarize what customers typically experience for a representative custom program. Programs with severe qualification requirements (aerospace flight hardware, nuclear-safety class, hazardous-area certification) extend the schedule; derivatives of an existing Thermometrics design compress it.
Ready to Get
Started?
Whether you need a single calibration certificate, a custom-engineered sensor assembly, or a full prototype qualification campaign, our technical team responds to every request within one business day.