Thermocouple Mounting Styles

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Thermocouple Mounting Styles

Comparing Thermocouple Mounting Styles: Bayonet, Melt Bolt, Clamp & More

When it comes to thermocouples, performance doesn’t just depend on what’s inside — how it’s mounted makes a big difference too. Whether you’re dealing with a tight nozzle on an injection molding machine or retrofitting sensors on an automotive line, the mounting style can make or break your setup. Here’s a quick breakdown of some of the most common mounting styles and how to decide which one fits your application best.

Style Comparison Chart

Mounting Style	Best For	Pros	Considerations
Bayonet	Injection molding, tooling	Easy install, adjustable length, reusable	May loosen in high vibration if not secured
Melt Bolt	Extruders, plastic processing	Accurate, high-temp rated, direct melt stream contact	Fixed install, not typically reusable
Clamp-On	Pipe surfaces, retrofits, temporary setups	Non-invasive, easy to move, quick to deploy	Less accurate than immersion, must ensure good contact
Nozzle/Ring Lug	Tight spaces, surface mounting	Low-profile, easy to retrofit	Limited to moderate temps, not for immersion
Adjustable Probes	Flexible installs, varied depths	Adaptable during install	May not hold calibration as well over time as fixed
Fixed-Length Probes	Repeatable installs, long-term reliability	Consistent readings, simple to spec once installed	Requires precise measurement before ordering

Explore Specs & Sensor Styles

Not sure which configuration fits your process? Check out our downloadable mounting style guide or explore product pages for more info:

Request a custom build ›

Which One’s Right for You?

Start by thinking about:
•   Temperature and process media
•   Whether you need immersion or surface sensing
•   Installation flexibility or permanence
•   Environmental concerns like vibration, washdown, or chemical exposure

Case in Point:

When an automotive supplier faced a supply chain crunch, they needed a quick-turn, custom RTD with precision temperature control to stay on schedule. Tempco delivered a made-to-order solution that fit perfectly into their existing system — proof that mounting and sensor style go hand in hand when downtime isn’t an option. See the full story ›

Choosing the right mounting style isn’t just a detail — it’s a decision that affects installation time, maintenance ease, and the accuracy of every reading. If you’re still unsure, our team is here to help match the sensor to the setup so you can get it right the first time.

Weighing The Options

Bayonet Thermocouples:
Quick and Adjustable

These are the go-to option for plastics processing, especially in injection molding. Bayonet styles feature a spring-loaded tip and can be installed with bayonet adapters that make adjustments simple. If you need something that’s easy to remove, reposition, or fine-tune after install, this one’s for you.

Pros:

Easy to adjust on-site
Flexible installation angles
Standardized for tooling setups

Cons:

Can loosen with heavy vibration if not secured properly

Clamp-On Thermocouples:
Surface Sensing Made Simple

Clamp-On Thermocouples: Surface Sensing Made Simple
For monitoring pipe or surface temperature, clamp-on thermocouples get the job done without the need to drill or tap. These are ideal when you don’t want to disturb your process line or when you need portability between machines. Clamp-on Thermocouple Tempco

Pros:

Non-invasive install
Reusable and movable
Ideal for retrofits or temporary useEasy to adjust on-site

Cons:

May not read as accurately as immersion sensors
Sensor contact with the surface must be tightly secured for consistent readings.

Melt Bolt Thermocouples:
Built for Harsh Plastics Environments

Designed specifically for injection molding and extrusion, melt bolts measure temperature right at the plastic melt stream. They come in both adjustable and fixed-depth styles and can withstand serious heat. If your goal is accuracy in a challenging environment, melt bolts are a solid choice.

Bayonet Thermocouple

Pros:

Direct, accurate temperature reading from the melt
Rated for high temperatures (up to 1400°F without Teflon®)
Designed for permanent installation

Cons:

Requires precise placement during installation
Not typically reusable once removed

Nozzle & Ring Lug Styles:
Small Space Specialists

In small spaces like nozzle tips or die assemblies, compact sensor styles like ring lugs or nozzle probes shine. They attach directly to existing fasteners or recesses to keep things tidy and efficient.

Lug Thermocouple

Pros:

•   Low profile
•   Fits into tight or confined locations
•   Easy to integrate with existing hardware

Cons:

• May not read as accurately as immersion sensors
• Sensor contact with the surface must be tightly secured for consistent readings

May 8, 2025

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Thermocouple Mounting Styles

Comparing Thermocouple Mounting Styles: Bayonet, Melt Bolt, Clamp & More