Buyer guide: Rosemount 3051S and Deltabar PMD75

Hey, people! We’re back with yet another set of product reviews for all you automation freaks and instrument geeks. Today we’re going back to differential pressure (DP) transmitters, with two formidable players: the Rosemount 3051S and the Deltabar PMD75. Yep, Emerson versus Endress+Hauser. What a match!

So what can you expect from these DP transmitters? Let’s find out. We’ll eyeball their features and see if they’ll fit into your process. Sound good? Heck yeah!

But keep in mind that these reviews examine only features, not performance. If you’ve used either of these devices, feel free to share your experience in the comments.

Rosemount 3051S 

Emerson has upped their game with this product, the  Rosemount 3051S. As one of the most relevant companies in automation, Emerson has innovative solutions for nearly every application, and this product is no different.


As I’ve said before, design-wise, a Rosemount is a Rosemount is a Rosemount. If you’ve used one, you’ve used them all. Now the 3051S comes in a few extra flavors such as high static and electronic remote sensor. But today, we’ll go with just the DP transmitter.

image of Rosemount 3051S
Courtesy of Emerson

Like every other Rosemount, the 3051S needs a handheld for configuration – no local setup, just your zero/span adjustment. But it has built-in sensors for readability and repeatability. It also promises 15 years of stability on its limited warranty.


The 3051S does the same as any other DP transmitter, measuring flow, level, and DP. It has a standard accuracy of 0.035 percent of span or an optional accuracy up to 0.025. And the optional has up to 0.04 percent of reading accuracy for flow. 

Emerson has done a tight job with the sealing system and offers a good range to fit almost any process. Of course, that range depends on the model, -62.16 to 62.16 millibars on one, -20.68 to 20.68 on another and so on. So read the manual for more on all that.

It also comes with a plenty of certifications, process connections, classifications, and external display options, making it a user’s paradise.


The 3051S offers protocols like analog, HART, FOUNDATION Fieldbus (FF), and WirelessHART. If you need PROFIBUS PA, then go for the 3051 without the S. The models have other differences besides letters, so make sure you check before you buy!

The 3051S comes in different housing styles too. For wireless, it has various antennas to improve range over a standard antenna, making a repeater unnecessary.

image of Rosemount-3051S
Courtesy of Emerson

And the 3051S and 3051 both have power advisory diagnostics. In a standard installation, you have parts like the junction box and cables that can succumb to water damage or other issues. These diagnostics can detect changes in voltage and resistance, reducing unscheduled downtime or failures and improving predictive maintenance.

Endress+Hauser Deltabar PMD75

Endress+Hauser has a rep more as an instrumentation dealer than a solution provider, although it offers both. Regardless, this show often sets the bar in flow and level measurement. Let’s check out the Deltabar PMD75 and see what it can do for you.


Nothing fancy here right off the bat. You can set up using the display, external push buttons, your handheld, or even remotely with a digital protocol, which makes for a good handful of options.

Image of Deltabar PMD75
Cortesy of Endress+Hauser

It comes with a few other nice features too, like a top display, mounted diaphragm seal, and hygienic approvals. On the downside, all the features don’t come on all the models, but the documentation doesn’t spell that out very well.


The PMD75 comes with great accuracy, 0.035 percent or an optional 0.025 percent. As for seals, the FMD77 and 78 have up to 0.075 percent accuracy, which will do for most processes. You can also install the transmitter 2, 5, or 10 meters away from the sensor using different cables.

The PMD75 has plenty of membrane materials to offer and a measuring range from -10 to +10 millibars or from -40 to +40 bar, with a high-pressure version too. And yes, the range depends on the model, so give that online manual a good hard look to make sure you know what you’re getting. 


The PMD75 offers analog, HART, FF, and PROFIBUS PA but no wireless. Also, the Deltabar S features the TempC membrane, a patented temperature compensator guaranteed to deliver the highest accuracy. And you get the histoROM data module, making it easy to manage process and device parameters. If you have a problem with the electronics, then save the parameters to the data module and swap them out. So saving parameters saves time!

image of Deltabar PMD75
Courtesy of Endress+Hauser

Table of comparison


Rosemount 3051S

Deltabar PMD75




simple, like all Rosemounts; local display for zero and span only, no setup standard design, but different models depicted under same name




good display; no local setup but plenty of data, like process variables, bar graphs, error messages, and diagnostics LCD display that can turn 90 degrees; four lines to show process values and graphics; comprehensive manual




piezoresistive sensor with patented Rosemount coplanar technology; huge list of membrane and wetted materials; guarantee of good performance and safety
piezoresistive sensor with a welded metallic membrane for reference accuracy, ambient temperature, and static pressure; FMD78 has the TempC, offering high accuracy and better safety, reducing errors from temp changes and other influences




standard – 0.035 percent span accuracy, ultra – 0.025 percent and 0.04 percent for flow 0.035 percent upgradable to 0.025 percent; FMD77 or 78 provides 0.075 percent




analog, HART, FF, and WirelessHART analog, HART, FF, and PROFIBUS PA



Fancy features

3051S and 3051 have power advisory diagnostic technology histoROM data module, TempC membrane on the FMD78



Both devices provide solid performance and good value. So find the features you need, scale out, and do some price checking. Either way you go, you’ll probably do okay. Of course, if the 3051S had PROFIBUS PA and the PMD75 had better accuracy, then you might wind up kinda stuck! Good thing they don’t then, isn’t it?

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