The Differences Between Rosemount’s Temperature Sensors 0068 and 0078: Which One Do You Actually Need?

If you’ve been browsing through instrumentation catalogs lately, you’ve probably found yourself scratching your head over model numbers. Specifically, the differences between Rosemount’s temperature sensors 0068 and 0078 might not be immediately obvious just by looking at the spec sheets. Both are solid pieces of equipment from Emerson, but trust me, these two aren’t twins—they’re more like cousins who went to different schools.

I’ve spent enough time in control rooms and out in the field to know that picking the wrong sensor can turn a simple install into a headache real quick. So let’s break this down like we’re grabbing coffee and talking shop.

The Quick Overview: One is for the Pipe, One is for the Pocket

Here’s the simplest way to think about it. The Rosemount 0068 is what I’d call a “straight shootin’” generalist. It’s a direct contact sensor, usually a resistance temperature detector (RTD) that physically touches the process medium. It’s your go-to for pipelines, tanks, and reactors where you can stab a thermowell into the flow.

The 0078, on the other hand, is a bit of a show-off. It’s a non-intrusive surface sensor. You don’t stick it in the pipe; you strap it onto the pipe. It’s designed for applications where you can’t drill a hole, don’t want to shut down the line, or need to measure the temperature of the pipe wall itself.

Digging into the Hardware

The 0068: The Classic Contact Sensor
Physically, the 0068 looks like what you probably picture when you think “industrial temperature sensor.” It’s got a rigid stem or a spring-loaded tip that ensures good contact with the bottom of the thermowell. This thing is built for accuracy. Because it’s immersed in the flow, it responds quickly to temperature changes in the fluid.

If you’re running a refinery or a chemical plant, you’re probably already using a dozen of these. They play nicely with Rosemount transmitters and are the industry standard for closed-loop control where precision matters.

The 0078: The Clamp-On Specialist
The 0078 looks totally different. It’s usually smaller, with a flat or curved face designed to mate perfectly with the pipe’s outer diameter. Often, it comes with a clamping mechanism—think hose clamps or spring-loaded brackets—to hold it tight against the surface.

Now, here’s the catch: because it’s measuring the temperature of the pipe wall, it’s always going to lag a little behind the actual fluid temperature. There’s metal in between, and if there’s insulation or scale on the pipe, your reading gets even fuzzier. But for applications where you can’t break the seal (think sanitary processes in food and bev, or high-pressure lines you don’t want to tap), the 0078 is a lifesaver.

Application Scenarios: Where They Shine

Let’s get practical. When would you actually pick one over the other?

Choose the 0068 when:

• You need high accuracy for process control (like ±0.1°C).

• You’re designing a new build and can install thermowells.

• The process fluid is moving fast and you need a fast response time.

• You’re dealing with high vibration (the 0068 can be built with support cones to handle this).

Choose the 0078 when:

• You can’t shut down the process to weld a thermowell.

• You’re measuring pipe surface temperature for energy efficiency or safety (like heat tracing).

• You need a temporary measurement for troubleshooting.

• Sanitary requirements forbid any penetration of the pipe wall.

Accuracy and Response Time: The Trade-Off

Honestly, if you put an 0068 and an 0078 on the same pipe, they’re going to give you different numbers. It’s not that one is “wrong,” but they are measuring different things.

The 0068 measures the internal temperature. The 0078 measures the external temperature plus ambient influences. If you have a hot fluid running through a cold room, the 0078 is going to read lower than the 0068 because the pipe is losing heat to the atmosphere.

The 0078 has also got a slower response time. It takes a while for the heat to travel through the pipe wall and into the sensor. If you’re monitoring a batch process where temperatures spike quickly, the 0078 might miss the peak. The 0068 will catch it almost instantly.

Installation Headaches and Wins

From an installation standpoint, the 0078 wins the “ease of use” award. No welding, no hot work permits, no draining the line. You literally clamp it on, slap some insulation over it, and you’re done.

The 0068 requires more planning. You need a thermowell (usually), which means you need to know the insertion length, the lagging extension, and you’ve got to weld a boss onto the pipe. It’s more permanent. But once it’s in, it’s set-and-forget for years.

Cost Considerations

I won’t quote exact prices because they fluctuate, but generally, the hardware cost is in the same ballpark. The real cost difference is in installation. If you factor in the labor, welding, and downtime required to install an 0068 versus the five-minute clamp-on of the 0078, the 0078 often comes out cheaper on retrofit jobs.

The Bottom Line

To put it bluntly: the differences between Rosemount’s temperature sensors 0068 and 0078 come down to “internal” versus “external.”

The 0068 is for when you need the real deal—the actual temperature of your process fluid. It’s accurate, responsive, and built for permanent installation.

The 0078 is for when you need a solution that doesn’t interfere with the process. It’s convenient, non-invasive, and perfect for retrofits or surface monitoring.

Neither is “better.” They’re just built for different jobs. So before you pick one, ask yourself: Do I need to know what’s happening inside the pipe, or is the pipe itself telling me enough?

If you’re still on the fence, drop a comment or reach out. Sometimes talking through the specific application is the only way to know for sure.