Time for a showdown between the Endress + Hauser Deltabar S PMD75 and the Emerson Rosemount 3051S pressure transmitters. Both devices have more than one option, but let’s just compare the differential pressure (DP) transmitters.

Deltabar S PMD75 vs Rosemount 3051S

Unboxing

I love writing this part. You can skip to the next section if you want, but I have to get my two cents in on the first impressions. Okay, the Deltabar S PMD75 looks like just a standard differential pressure transmitter. It has a local display, two ways to set it up, different housing materials, and – this part’s a tad weird – a display on the top.

A top display looks strange to me, but if it helps you see the process variable, then I’m on board. On the negative side, if you want a diaphragm seal or capillary you need to stop here and check your return policy, but we’ll go into that later.

Deltabar s pmd75
Courtesy of Endress+Hauser and Emerson Automation Solutions

Similarly, the 3051S looks like all Rosemount products. There is a local display that can do zero and span adjustments, but it won’t let you set up locally.

Emerson kept the same name on different models for different applications, and some people may like that brand unity. Others may find it confusing and prefer different names like on Endress+Hauser’s products. So we have apples and oranges on this one.

Display

The Deltabar S PMD75 has a cool LCD display that can turn 90 degrees and set up the transmitter. Although other vendors have the same, here it feels like an advantage. It has a four-line display that can show the process value, a cool bar graph, and other things. And best of all, you can use it without the manual! Good job, Endress+Hauser.

The 3051S also has a cool display, but you can’t set up the transmitter with it. On the positive side, the display offers plenty of data, like process variables, bar graphs, error messages, and diagnostics.

Sensor

Both devices have pressure sensors, of course. The Deltabar S PMD75 has a piezoresistive sensor with a welded metallic membrane. You can choose from different membrane materials to find one that suits your process. The sensor provides reference accuracy, ambient temperature, and static pressure.

If you need a transmitter with a diaphragm seal, the FMD78 has the TempC membrane. Nope, not a typo. The FMD78 is the PMD75 with a diaphragm seal and name change. Remember the chat about brand unity earlier? Yeah, Endress+Hauser went the oranges route.

rosemount 3051S
Courtesy of Emerson Automation Solutions

Anyway, Endress+Hauser patented the TempC technology for its diaphragm seals. Basically, TempC offers high accuracy and better safety, minimizing errors from temperature changes and environmental influences.

As for the 3051S, it has a piezoresistive sensor with a small bonus, the patented Rosemount coplanar technology. Emerson says it optimizes performance in level, flow, and pressure measurements. It also comes with a huge list of membrane materials or process wetted materials and a guarantee of good performance, safety, and lifetime application.

The super version – how cool is that? – has an all-welded hermetic SST design. And what does that mean? That means high field reliability. Not bad, Emerson.

Performance

Both devices offer excellent accuracy. The Deltabar S PMD75 goes up to 0.035 percent, with an option of up to 0.025 percent. If you need the FMD77 or 78, the accuracy goes to 0.075 percent. It also provides long-term stability, which varies a little depending on the measuring cell you choose. For example, on a measuring cell of 40 bars, you can get 0.050 percent in one year, 0.070 percent in 5 years, and 0.100 percent in 10 years. Pretty good.

Deltabar S PMD75
Courtesy of Endress+Hauser

The 3051S offer three different accuracies. The standard, called classic, gives you up to 0.035 percent span accuracy. The ultra offers up to 0.025 percent and the ultra for flow up to 0.04 percent reading accuracy. For stability, Emerson went kinda generic, claiming up to 0.15 percent of upper range limit for 15 years with some conditions. Eh.

Integration

Neither device brings anything new here. The Deltabar S PMD75 lets you connect through analog, HART, FOUNDATION Fieldbus, and PROFIBUS PA. Not bad, but as a digital native, I have to say it should have a wireless option. You can use an adapter, but you’ll get less battery performance than with wireless tech already built in. Going wireless can improve monitoring, machinery performance, reliability, and connection to the Industrial Internet of Things concept.

Deltabar S PMD75
Courtesy of Endress+Hauser

On the 3051S, you have similar options – analog, HART, FOUNDATION Fieldbus, and WirelessHART. I miss the PROFIBUS PA option, but you can get it with the 3051. The 30151 may lack accuracy and stability, but at least you have the option available.

Information and documentation

I know the marketing critters love reading this bit. I’ve mentioned my experience with Endress+Hauser website before, but if you missed it, then here you go – hard-to-find information, poor user interface, and nonexistent mobile experience. Harsh but true.

The documents themselves give good information and better navigation than the website, once you find them. The company videos follow the standard B2B format, but they provide decent info as well.

However, someone has started working on it! Level solutions now have their own user-friendly, mobile-friendly site! How cool is that? Sadly, it won’t let you download files. If you want those, then you have to go back to the main site.

Deltabar S PMD75
Courtesy of Endress+Hauser and Emerson Automation Solutions

Emerson, on the other hand, has an excellent website you can navigate through laptop, mobile, and tablet. Furthermore, it has blogs and microsites that pop up when you search for a product and clear documentation.

When I started to write this week’s review and comparison, the Emerson site had some access issues. I decide to tweet the company to let someone know but didn’t expect much response. To my surprise, I got a prompt “problem solved!” reply.

Nice job flipping a bad user experience into a good one, Emerson.

Deltabar S PMD75
Courtesy of Emerson Automation Solutions

Fancy features

We don’t have too many fancy features here. However, we can highlight the TempC membrane on the FMD 78, a patented temperature compensation solution guaranteed to deliver the highest accuracy. It also has the histoROM data module, where you can easily manage process and device parameters.

The 3051S and 3051 both have power advisory diagnostic technology. These diagnostics can detect changes in voltage and resistance, which will help you avoid unscheduled downtime, failures, and other problems.

Conclusion

Both differential pressure transmitters should provide excellent performance and apply in various processes and segments. Check which features you need, scale out the device, and find out the price. These companies are experts in their business, so it looks like a win, whichever you pick.

What’s the best differential pressure transmitter for you?

Deltabar S PMD75
Courtesy of Giphy

Table of comparison:

Deltabar S PMD75 vs Rosemount 3051S table of comparison
Courtesy of Endress+Hauser and Emerson Automation Solutions
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