Temperature Sensors Beyond the Basics

Finding the Right Temperature Measurement Partner

You need temperature sensors, but you’re not sure which type fits your application. Maybe you have a short lead time and can’t find anyone who stocks what you need. Or you need reliable temperature measurement in the harshest conditions where standard catalog offerings don’t work.

Here’s what most manufacturers will tell you: “We can build that, but it’ll be custom pricing and 12 to 16 weeks.” They treat anything outside their catalog as a special order that costs more and takes longer.

At SSi Temperature Sensors, we work differently. Whether you need exactly what’s listed in our catalog or something customized for your specific application, the price is the same and the lead time is the same. We engineer every sensor to your exact specifications, but we do it at Off-the-Shelf Speed with off-the-shelf pricing.

Engineered-to-Order with Off-the-Shelf Speed isn’t just our tagline. It’s how we operate.

What Makes Temperature Measurement Complex

Temperature measurement technology selection impacts accuracy, reliability, and total cost of ownership. The right sensor choice depends on your specific application requirements, not on what is listed in a catalog.

SSi Temperature Sensors Product Line:

We manufacture the complete range of temperature measurement instruments, all engineered to your specifications:

• RTDs (Resistance Temperature Detectors): Platinum RTDs in any configuration, including high-accuracy models for critical process applications
• Thermocouples: All standard types (J, K, T, E, N, R, S, B) plus specialty designs
• Thermowells: Machined, drilled, or fabricated in any material and configuration
• Temperature transmitters: In-head and remote mount, HART and analog
• Surface temperature sensors: Including electric trace designs, tubeskin sensors, washer thermocouples, and heavy-duty pipe clamp sensors
• Multipoint sensor assemblies: Multiple measurement points in a single assembly and field-adjustable
• Specialty designs: High-pressure assemblies, replacement elements for obsolete products, and custom OEM designs
• Connection heads and accessories: Explosion-proof, weatherproof, and general-purpose enclosures
• Displays and indicators: Local temperature indication with various mounting options

The best part? Everything we build is engineered to your exact specifications and comes at the same standard pricing. Whether you order a common configuration or something highly specialized, you pay the same price and get the same fast delivery.

The Catalog vs. Non-Catalog Pricing Myth

Here’s how most temperature sensor manufacturers work: they publish a catalog with standard configurations and standard prices. Order from the catalog and you get catalog pricing. Need something different? Now it’s “custom” and you’re looking at premium pricing and extended lead times.

We don’t play that game. There is no premium for non-catalog items because we don’t have catalog items in the traditional sense. Everything is built to order.

Think about what this means for your project:

An 11.375-inch insertion length should not cost more or carry a longer lead time than a 12-inch insertion length simply because it is labeled “non-standard.” Likewise, an RTD built with Hastelloy C-276 should reflect only the material cost difference, not an added premium or extended lead time for being non-standard.

This isn’t a promotional pricing strategy. It’s how we operate every day. We’ve eliminated the artificial distinction between “standard” and “custom” because it doesn’t make sense when you’re Engineering-To-Order anyway.

The lead time is the same too. We’re not delaying your order to queue up custom work. Your order goes into production using the same processes, whether you need something common or something we’ve never built before. We are able to do this because we manufacture everything in-house, in our Houston, Texas Facility.

Understanding Your Temperature Sensor Options

Let’s break down the main types of industrial temperature sensors and when each one makes sense.

Resistance Temperature Detectors (RTDs):

An RTD sensor uses a simple principle: electrical resistance changes predictably with temperature. Most use platinum because it’s stable and repeatable. When people ask “how does an RTD work,” here’s the short answer: a precision platinum element changes its electrical resistance as temperature changes, and we measure that resistance to determine temperature. The relationship is predictable and accurate.

Thermocouples:

These work differently. When you join two dissimilar metals and heat one junction, you generate a small voltage. That voltage tells you the temperature. Thermocouples are workhorses in high-temperature applications because they can handle extremes that would destroy other sensors.

How to choose RTD vs Thermocouple

This is one of the most common questions we hear. The answer depends less on the technology and more on what you’re trying to measure.

RTDs give you better accuracy and stability. If you’re controlling a critical process where a half-degree matters, you probably want an RTD. They’re more stable over time, so you won’t be recalibrating constantly.

Thermocouples handle extremes better. Need to measure 2,000°F? Thermocouple. Need fast response in a rapidly changing process? Thermocouple. They’re also simpler and more rugged in harsh environments.

Here’s the practical difference: RTDs are typically better when accuracy is your top priority and you’re in a moderate temperature range. Thermocouples are better when you’re dealing with extreme temperatures or need very fast response times.

But you don’t have to guess. Tell us what you’re measuring and what matters most in your application. We’ll recommend the right sensor technology and build it to your exact specs.

Temperature Measurement Across the Full Spectrum

We handle temperature measurement from cryogenic lows to extreme highs. Not many manufacturers can say that credibly.

Cryogenic Applications:

Measuring extreme low temperatures requires specialized sensors and materials. We build sensors for liquefied gas storage, aerospace fuel systems, and research applications where temperatures drop to levels that would make standard sensors useless. If you’re working with LNG, liquid hydrogen, or other cryogenic fluids, we’ve solved similar problems before.

Extreme High Temperature Applications:

On the other end of the spectrum, we manufacture high-temperature sensors with protection tubes rated for environments where metal melts. Our ceramic protection tubes handle temperatures that would vaporize standard materials:

• Alumina tubes: up to 3,400°F (1,871°C)
• Mullite tubes: up to 3,000°F (1,648°C)
• Hexoloy tubes: up to 2,900°F (1,593°C)

These sensors serve power generation plants, metal processing operations, glass manufacturing, and other industries where “hot” is an understatement. The protection tube material selection depends on your specific temperature range and process chemistry.

Thermowells: More Important Than Most People Think

A thermowell is essentially armor for your temperature sensor. It protects the sensor from your process while still allowing accurate measurement. Get the thermowell design wrong, and you’ll either get bad readings or catastrophic failure. We’ve seen both.

What Goes Into Proper Thermowell Design:

Material selection matters. Your thermowell needs to handle your process fluid without corroding, eroding, or contaminating what you’re processing. Stainless steel works for many applications, but you might need exotic alloys for aggressive chemicals or high temperatures.

Wake frequency is the engineering piece most people skip. When process fluid flows past a thermowell, it can create vibrations. If those vibrations match the thermowell’s natural frequency, you get resonance. That’s when thermowells fail spectacularly. We run thermowell wake frequency calculations per ASME PTC 19.3 TW 2016 when required or requested to ensure that won’t happen in your application.

Insertion length and diameter need to be optimized for your process. Too long and you risk mechanical failure. Too short and you’re not measuring what you think you’re measuring. We can work through these calculations to ensure the insertion length and diameter meet your specifications.

Why Use Temperature Switches for Process Control

A temperature switch is simpler than a continuous measurement system. It just tells you when the temperature crosses a threshold. Need to turn on cooling when a motor gets too hot? Need to shut down a heater when the temperature reaches the setpoint? That’s what temperature switches do.

We build them for everything from basic HVAC control to critical safety shutdowns. The switch setpoint, deadband, and enclosure type all get configured for your specific application.

Solving the Inventory Problem

Here’s a common pain point: you need to stock multiple sensor lengths for different applications. A sensor that’s 6 inches too long doesn’t work, and you can’t exactly stretch one that’s too short. So you end up with a storeroom full of specific lengths, each one only useful for particular installations.

Our field-adjustable industrial-grade temperature sensor designs fix this. You can cut the sensor to the exact length you need during installation.  Stock fewer part numbers, reduce inventory costs, and still have the right sensor for each application. It’s one of those simple solutions that makes maintenance much easier.

Complete Temperature Measurement Systems

Sometimes you need more than just a sensor. We build complete systems with everything integrated:

• Temperature transmitters convert sensor signals to standard 4-20mA outputs that your control system can read. We mount them in-head to reduce wiring costs and improve signal quality, or remotely if your application requires it. HART-enabled transmitters add digital communication on top of the analog signal.
• Connection heads protect the wiring and provide a junction point. We offer them in explosion-proof, weatherproof, and general-purpose ratings depending on your area classification.
• Multipoint sensor assemblies measure temperature at multiple points using a single process penetration. These are common in catalyst beds, large storage tanks, and any application where you need a temperature profile rather than a single point measurement.

All of this gets Engineered-to-Order as a complete system rather than cobbled together from separate components. It works better and costs less than sourcing everything separately.

How to Choose the Right Temperature Sensor

Three questions usually narrow down the options:

1. What are you measuring? Temperature range matters most. Cryogenic applications need different sensors than furnace monitoring. Accuracy requirements vary, too. Some processes need precision to a fraction of a degree. Others just need to stay within a range.
2. What’s your process like? Corrosive chemicals? High pressure? Vibration? These factors determine material selection and protection requirements. A sensor that works fine in clean water might dissolve in sulfuric acid.
3. How does it integrate with your system? Do you need local indication, or does the signal go to a control system? What signal type does your existing equipment accept? These decisions affect which transmitter and display options make sense.

Our engineering team walks through these questions with you. We’ve built sensors for thousands of applications, so we can point you toward solutions that have worked in similar situations.

Why SSi Temperature Sensors Work Differently

Most temperature sensor manufacturers operate from catalogs. They stock standard sizes and charge premium prices with long lead times for anything custom. We turned that model upside down.

Everything is Engineered-to-Order; nothing is stocked in standard sizes. This sounds counterintuitive, but it’s faster and more cost-effective. Here’s why it works:

We manufacture everything in-house at our Houston facility. Our team knows how to build sensors efficiently because we do it every day. When your order comes in, whether it matches something we built yesterday or requires a new configuration, our engineering and production process stays the same. We’re not scrambling to figure out how to make something unusual. We’re just building another sensor.

The result: Engineered-to-Order with Off-the-Shelf Speed. You get exactly what your application needs in the same timeframe; others need to ship a standard product. And because this is how we always operate, there’s no custom engineering surcharge.

Think about what you’re buying. You don’t want a sensor that’s close to your requirements. You want one that’s right for your application. Why should that cost more or take longer?

How We Work With You

The process is straightforward. Tell us what you’re measuring and what your process conditions are. Our engineering team reviews your requirements and develops a solution. We’ll send you drawings and specs for approval before we start manufacturing.

Once you sign off, we build your sensors using the same manufacturing processes we use every day. You get sensors built exactly to your specifications, with all the test documentation and certifications you need.

Installation is simpler because everything was designed for your specific application. No field modifications, no compromises, no wondering if it’ll work.

Getting It Right Matters

Temperature measurement affects product quality, process efficiency, and safety. A sensor that’s not quite right leads to measurement errors. A poorly designed thermowell fails during operation. These problems cost real money and create real headaches.

Whether you’re measuring cryogenic temperatures in aerospace applications or tracking heat in industrial furnaces, we can build what you need. The sensor technology, protection, and configuration all get optimized for your specific application.

We’ve been doing this since 1995. Our team has solved temperature measurement problems across every major industry. If you’re measuring temperature and the standard catalog offerings don’t quite fit, talk to us.

Engineered-to-Order with Off-the-Shelf Speed. Same price. Same speed. Specifically fits your application.

For more information about temperature measurement solutions for your application, contact your local SSi Temperature Sensors Representative.