LVDTs for High Temperature Applications

Written by transtek_admin on 10/01/2025

Linear Variable Differential Transformers (LVDTs) are well known for being versatile, and able to reliably function in many challenging environments. They withstand threats of vibration, pressure, corrosion, and more. Perhaps the most demanding challenge they face is extreme heat. Standard LVDTs simply can’t survive the heat, but their designs can be modified so they can deliver reliable position measurement.

Why Do Standard LVDTs Fail in High Heat?

So, why exactly are extreme temps a threat to LVDTs? While their housings are durable, it’s their internal winding assemblies that are vulnerable. When subjected to high heat, standard LVDT materials, such as epoxy sealants and tape, typically break down. Further, wire insulation will dissolve under certain temperatures, which destroys the carefully wound coils at the heart of the unit. While these materials are a smart choice and cost effective for standards, certain considerations must happen to make them durable. Let’s take a look at them.

When exposed to high temperatures, standard LVDT materials break down catastrophically. Epoxy, sealants, and tape deteriorate, causing the unit to fall apart. Standard wire insulation dissolves under heat, destroying the carefully wound coils that make LVDT operation possible. While these standard materials are cost-effective for normal applications, they’re inadequate for extreme temperature environments.

Even if the materials don’t completely fail immediately, performance and accuracy suffer. For instance, the output will shift slowly over time. The sensor initially appears fine, but measurements become less and less accurate. This happens since different materials expand at different rates as the temperature rises. Even if the unit’s winding assembly hasn’t moved, thermal expansion effects cause the output to change.

Standard LVDTs will begin showing problems around 250°F. Conversely, high-temperature designs operate reliably up to 400°F. This is the threshold where everything still works very well together. Though units can be built to withstand temperature in excess of 450°F,  but performance characteristics will start changing significantly due to material temperature coefficients.

High-Temperature Solutions

In order to withstand the threat of high temperatures, LVDTs require completely different materials and construction. Epoxy is replaced with high-temperature alternatives, or specialized joining techniques. Similarly, the sealants and tapes need to be upgraded to other materials that can maintain their properties. Let’s not forget the wires! They must have a specialized coating on them to withstand the heat. This is true for both internal the windings and external cables.

As you can imagine, these material upgrades do come with higher price tags. But they are absolutely required for uses where heat can’t be avoided.

High-Temp LVDT Applications

We’ve worked with many customers over the years overcome their high temperature  application challenges. Here are few:

Downhole Drilling Operations – these processes are prone to extreme temperatures which will quickly destroy standard sensors; within hours. High-temperature LVDTs provide accurate and critical position feedback in these very harsh environments.

Drilling Simulation – in a related use, facilities that test core samples under extreme conditions, require sensors that will also maintain accuracy throughout extended high-temperature test cycles.

Aerospace Applications – these include rocket launch platforms and space vehicles. Even when actual temperatures don’t reach extremes, engineers often specify high-temperature units for their superior materials and reliability.

Military Applications – require all types of equipment that must function flawlessly across wide environmental threats, including potential extreme heat exposure.

Industrial Process Control – steel mills, glass manufacturing, and other high-temperature facilities require precise position measurement near molten materials where temperatures will easily exceed standard sensor limits.

Heavy Hydraulic Systems – high-temperature environments, such as large-scale forging operations, rely on high-temperature LVDTs for reliable operation despite the significant thermal stress they are subject to.

The Bottom Line

When an LVDT’s use is prone to extreme temperatures, there’s no choice. They must be designed to specifically handle the heat, and constantly deliver accurate measurements. For applications in excess of 250°F, the investment in proper high-temperature sensors pays off through reduced downtime and maintained accuracy, regardless of how hot conditions get.

Posted Under: LVTDs

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