PMC51B vs VEGABAR 82: Pressure Transmitter Cross-Reference

At a Glance. When an instrument becomes hard to source, the natural question is which transmitter from another manufacturer can replace it. Two of the most-requested process pressure transmitters in our stock are the Endress+Hauser Cerabar PMC51B and the VEGA VEGABAR 82. Both are digital transmitters with metal measuring cells and ±0.1 percent accuracy, which makes them similar — not interchangeable without checking. Both are catalogued under pressure measurement, alongside their respective brands, Endress+Hauser and VEGA.

1. What the two instruments have in common

On paper the overlap is large. In practice the substitution decision is decided by four items that a datasheet comparison at headline level does not capture.

2. The four items that break a substitution

Item 1 — Process connection and wetted parts

The measurement starts at the diaphragm. Connection size, thread or flange standard, diaphragm material, and whether the version is flush-mounted all change the part number, and a mismatch here means a mechanical rework rather than a firmware change. It is the single most common reason a substitution fails at commissioning.

Item 2 — Measuring range and turndown

Two transmitters can both be described as ±0.1 percent and still have very different ranges and turn-down behaviour. Accuracy is normally quoted relative to a defined span; if the required range falls at the extreme end of a sensor's capability, the effective accuracy is worse than the headline figure. Compare the sensor range, not the marketed accuracy class.

Item 3 — Output, protocol and configuration

Both families use HART, but a differing device description means the host system, the handheld communicator or the asset-management software may need a new driver file. Where the transmitter is integrated into a control system, plan the configuration migration rather than assuming the device will appear identically.

Item 4 — Approvals and environment

Hazardous area approval, ingress protection, ambient temperature range, and requirements for hygienic design each eliminate whole model ranges. An approved version of one family is rarely matched exactly by the nearest model of another.

3. When substitution is straightforward, and when it is not

Substitution is straightforward when the transmitter is a standalone 4–20 mA or HART device with a standard thread connection, a generously sized range and no special approval. It becomes a project when any of the following applies:

• The instrument is part of a hygienic process with certified cleaning
• Hazardous area approval is required
• The connection is a sanitary or flush-mounted flange
• The measuring range is narrow relative to the sensor range
• The device is referenced by an asset-management system that requires the exact model

4. Planning a wider instrument standardisation

Plants that run both brands often use the opportunity to standardise the measurement chain. If the pressure transmitter sits alongside a flow and a level measurement, consider whether the same project should address the adjacent instruments: Promass F 100 for Coriolis mass flow and VEGAPULS 64 for radar level are common companions in a process line. Standardising on one platform reduces spare parts, training and configuration effort — but only if it is done at the project level rather than instrument by instrument.

5. What to send us

1. The existing instrument's full model code and order code, plus a photo of the nameplate
2. Measuring range actually configured, not the sensor's maximum
3. Process connection drawing and wetted material
4. Output signal and the host system that reads it
5. Area classification and required certifications

Our team cross-references between the two brands regularly and will confirm whether a direct substitute exists or whether the application needs a mechanical or configuration change. Browse the Endress+Hauser and VEGA stock for current availability.