Endress+Hauser Deltabar is a family of transmitters designed for differential pressure (DP) measurement in liquid and gas processes. Depending on the selected device and measurement arrangement, Deltabar transmitters can be used for hydrostatic level measurement, flow measurement and monitoring pressure drops across filters and process equipment.
Differential pressure is the difference between two pressure points:
[
\Delta P=P_1-P_2
]
Here, (P_1) and (P_2) represent the pressures applied to the high-pressure and low-pressure sides of the transmitter. Depending on the application, the measured difference can be used directly as a differential pressure value or converted into a level or flow measurement using an appropriate calculation method.
Selecting the correct Deltabar model requires more than checking the measurement range. Differential pressure range, static line pressure, process temperature, wetted-part materials, process connections, communication protocol and required certifications must all be evaluated together.
For the manufacturer's product family information, refer to the Endress+Hauser Deltabar differential pressure measurement page.
The following table summarizes key product information published by the manufacturer. These values provide a general comparison; the technical documentation and complete order code of the selected configuration must be used for final suitability verification.
|
Model |
Key published specifications |
Typical evaluation areas |
|
PMD50 |
Measuring cell range: 100 mbar–40 bar; standard accuracy up to 0.065%, Platinum option up to 0.055% |
Standard differential pressure, level and flow applications |
|
PMD63B |
Measuring cell range: 100 mbar–40 bar; standard accuracy up to 0.075%; HART, PROFIBUS PA and PROFINET over Ethernet-APL options |
Low DP measurement under high static pressure, filter monitoring and advanced process applications |
|
PMD75B |
Differential pressure measurement range listed up to 40 bar; standard accuracy up to 0.05%, Platinum option up to 0.035% |
Higher measurement performance, advanced diagnostics and demanding process conditions |
|
PMD78B |
Measuring cell range: 100 mbar–40 bar; standard accuracy up to 0.1%; process temperatures up to 400 °C with suitable diaphragm-seal configurations |
High-temperature processes and applications requiring diaphragm seals |
|
PMD55 / PMD55B |
Device generation and exact type must be verified |
Existing instrument identification and potential replacement assessment |
|
FMD71 / FMD72 |
Electronic differential pressure system using two sensors and one transmitter |
Level measurement in pressurized or vacuum tanks |
Technical note: Accuracy figures represent maximum published performance values. Actual measurement performance depends on the selected variant, calibration, measurement range and operating conditions. The differential pressure measuring range, permissible static line pressure and overpressure limits are separate parameters and must not be treated as interchangeable.
Manufacturer sources: PMD50, PMD63B, PMD75B, PMD78B.
PMD50 is a metal-membrane transmitter designed for differential pressure measurement in liquid and gas applications. With a suitable measurement arrangement, it can also be considered for level and flow measurement.
Measuring cell range: 100 mbar–40 bar
Standard accuracy: up to 0.065%
Accuracy with the Platinum option: up to 0.055%
Wetted diaphragm options include 316L, Alloy C and gold-coated versions.
HART communication is specified in the product documentation.
For direct process-connection configurations, the manufacturer's product page lists a process temperature range of −40 °C to +110 °C.
Higher process temperatures may be possible with suitable diaphragm-seal configurations; the manufacturer's product information lists temperatures up to 400 °C for applicable arrangements.
Source: Endress+Hauser PMD50 technical product page.
Differential pressure monitoring across filters and process lines
Flow measurement with a suitable primary element
Level measurement in closed tanks, subject to process conditions
Standard differential pressure applications that do not require more advanced functions
Important selection consideration: When diaphragm seals are used, the filling fluid, capillary length, installation geometry and temperature effects must be evaluated alongside the temperature limit. The maximum temperature specified for a product family must not be applied automatically to every directly connected PMD50 configuration.
PMD63B is a model to consider when low differential pressure must be measured under high static pressure. The manufacturer identifies hydrostatic level measurement in pressurized process tanks and differential pressure monitoring across filters among its typical applications.
Measuring cell range: 100 mbar–40 bar
Standard accuracy: up to 0.075%
The manufacturer lists 316L for the process diaphragm.
HART, PROFIBUS PA and PROFINET over Ethernet-APL communication options are listed in the product-family technical information.
Depending on the configuration, diaphragm seals and capillaries may be available on one or both sides.
The manufacturer specifies TempC membrane technology intended to reduce the effects of temperature changes.
Source: Endress+Hauser PMD63B.
Differential pressure range: Establish the expected minimum and maximum DP values, not only the normal operating point.
Static line pressure: Verify the common line pressure and pressure variations that may occur on both sides.
Communication: Match HART, PROFIBUS PA or PROFINET over Ethernet-APL to the existing automation architecture.
Process connection: Verify requirements for flanges, hygienic connections, diaphragm seals and capillaries.
Approvals: Check whether the selected order configuration meets hazardous-area, hygienic-process or functional-safety requirements.
The presence of several communication protocols in a product family's documentation does not mean that every instrument supports all protocols simultaneously. The technical documentation and complete order code of the selected variant must be checked.
PMD75B can be considered for applications where measurement performance and monitoring of instrument status or process anomalies are important.
The product information lists a differential pressure measurement range of up to 40 bar.
Standard accuracy: up to 0.05%
Accuracy with the Platinum option: up to 0.035%
Maximum process pressure is listed as 420 bar on the manufacturer's product page.
Wetted diaphragm material options include 316L, Alloy C, tantalum, Monel and gold-coated versions.
Heartbeat Technology provides instrument verification and monitoring functions.
The manufacturer specifies functions for detecting process anomalies such as impulse-line blockage.
Source: Endress+Hauser PMD75B.
Applications requiring a lower measurement error
Processes where monitoring impulse-line condition is important
Applications benefiting from instrument verification and status monitoring
Processes requiring specific wetted materials and connection options
Critical distinction: The maximum process pressure of 420 bar listed for PMD75B does not mean that the differential pressure measurement range is 420 bar. Static pressure capability, measurable differential pressure range and overpressure limits must be assessed separately.
Standard and Platinum accuracy values also depend on the selected performance option and the manufacturer's specified reference conditions. They do not guarantee identical field accuracy in every installation.
PMD78B is a differential pressure transmitter to consider where process and ambient temperature effects are important. The manufacturer specifies TempC membrane technology intended to reduce the effects of temperature changes on measurement.
Measuring cell range: 100 mbar–40 bar
Standard accuracy: up to 0.1%
Process temperatures can reach up to 400 °C with suitable diaphragm-seal configurations.
Wetted-part and diaphragm options include 316L, Alloy C, tantalum, Monel, PTFE and gold-coated versions.
The manufacturer's product information lists maximum static process pressure up to 160 bar, depending on configuration.
Source: Endress+Hauser PMD78B.
In diaphragm-seal systems, process pressure is transmitted through the diaphragm and capillary to the transmitter's measuring cell. The temperature behavior of the filling fluid, capillary length and installation position can affect measurement performance.
The following parameters should be evaluated together:
Minimum and maximum process temperature
Static pressure and differential pressure range
Diaphragm-seal type and material
Capillary length and installation geometry
Filling-fluid suitability for the process temperature
Chemical properties of the process fluid and material compatibility
The 400 °C value is not an unconditional operating limit for every PMD78B variant. It represents a maximum specified for suitable diaphragm-seal configurations. The complete order code and technical documentation must be checked for the selected instrument.
PMD55 and PMD55B should not automatically be treated as interchangeable during quotation, maintenance or replacement projects. The device generation, exact type and technical specifications must be verified before a direct replacement is recommended.
If an existing instrument is to be replaced, collect the following information:
Instrument nameplate photograph and complete order code
Measurement range and calibration information
Process connection and diaphragm material
Static pressure and process temperature
Output signal and communication protocol
Power supply and electrical connection
Required certifications and safety approvals
Documentation for older PMD55 instruments may differ from current product-family information. Product status and any recommended replacement must be verified against the existing instrument's complete order code and the manufacturer's current documentation.
FMD71/FMD72 use a different system architecture from a conventional single-transmitter differential pressure arrangement. This electronic DP approach uses two pressure sensors and one transmitter to evaluate pressures measured at the lower and upper parts of a tank.
In pressurized or vacuum tanks, level calculations must account for liquid density, tank headspace pressure and the sensors' installation points.
Identify the lower and upper tank measurement points.
Verify that the sensors' measurement ranges suit the process conditions.
Include liquid density and changing process conditions in the level calculation.
Check pressure, temperature and material compatibility.
Confirm integration with the existing automation system.
Manufacturer reference: Electronic differential pressure measurement.
Replacement warning: FMD71/FMD72 are not direct substitutes for every conventional DP transmitter. Converting a mechanical DP arrangement to an electronic DP system requires a new assessment of sensor placement, connections, process calculations and control-system integration.
The pressure difference between a filter's inlet and outlet can be monitored to track pressure loss and potential clogging. Alarm thresholds should be defined according to the filter design and process requirements.
Liquid level can be calculated from hydrostatic pressure difference. Liquid density, tank headspace pressure, connection points and zero/elevation settings are important for accurate results.
Flow can be calculated from the differential pressure generated by a suitable primary element, such as an orifice plate. Transmitter selection alone is not sufficient; primary-element sizing, fluid properties, pressure and temperature conditions must also be considered.
In many idealized differential-pressure flow applications, flow is related to the square root of differential pressure. An appropriate square-root extraction and scaling method is therefore required to convert the transmitter signal into a flow value.
The pressure difference between the inlet and outlet of a pump, heat exchanger or process line can help monitor equipment performance. Measurement points and alarm limits should be determined according to the system design.
|
Application requirement |
Models to consider initially |
Critical parameters to verify |
|
Standard differential pressure measurement |
PMD50 |
DP range, temperature, connection and materials |
|
Low DP measurement under high static pressure |
PMD63B |
Static pressure, low DP range and installation arrangement |
|
Advanced measurement performance and diagnostics |
PMD75B |
Performance option, measurement range and pressure limits |
|
High-temperature process |
PMD78B |
Diaphragm seal, capillary, filling fluid and temperature |
|
Electronic DP level measurement in a pressurized tank |
FMD71/FMD72 |
Two-sensor architecture and application suitability |
|
Replacement of an existing instrument |
Candidate selected from the exact existing instrument type |
Order code, connection, electrical properties and certifications |
This table is intended for preliminary screening, not as a final model recommendation. Final selection must be based on process data and the manufacturer's technical documentation for the relevant configuration.
Correct instrument selection alone does not guarantee accurate measurement. During installation and commissioning, check the following:
High- and low-pressure sides: Confirm that the pressure connections are correctly assigned.
Impulse lines: Assess leaks, blockages, gas or liquid pockets and freezing risks.
Static pressure: Verify that the common line pressure remains within the instrument's permitted limits.
Measurement range: Confirm that the calibrated range matches the actual process conditions.
Zero and scaling: Check calculation and scaling settings for level and flow applications.
Installation and temperature: Verify that diaphragm seals, capillaries and transmitter placement comply with the technical documentation.
Electrical and communication connections: Check power supply, wiring, protocol and control-system compatibility.
Certifications: Verify hazardous-area and functional-safety requirements against the ordered variant.
Before performing maintenance or changing connections on pressurized equipment, follow the plant's isolation, depressurization and safety procedures.
|
Symptom |
Possible causes |
Initial checks |
|
Measurement remains constant |
Blocked impulse line, closed valve or no process change |
Check valve position, impulse lines and process conditions using safe procedures |
|
Zero-point shift |
Incorrect zero setting, installation effects or reversed pressure connections |
Verify pressure connections, measurement range and installation conditions |
|
Fluctuating measurement |
Process pulsation, vibration or gas/liquid pockets in impulse lines |
Examine process dynamics and impulse lines |
|
Incorrect level calculation |
Density variation, tank headspace pressure or incorrect scaling |
Reassess level calculation, density and measurement points |
|
Incorrect flow value |
Incorrect primary-element data or square-root/scaling settings |
Verify primary-element calculations and transmitter output configuration |
|
Communication failure |
Incorrect protocol, wiring, power supply or instrument configuration |
Compare the complete order code, communication version and automation settings |
|
Diagnostic message |
Instrument status, configuration issue or process limits exceeded |
Follow the diagnostic instructions in the relevant model's operating manual |
This table is a general initial troubleshooting guide, not a definitive fault diagnosis. Diagnostic messages, the instrument manual and field conditions should be evaluated together.
When requesting a quotation or assessing a replacement for an Endress+Hauser Deltabar, the complete order code is essential for identifying the instrument configuration.
The following parameters should be compared:
Model and complete order code
Measuring cell and calibrated measurement range
Static line pressure and overpressure limits
Process connection and flange standard
Diaphragm and wetted-part materials
Process and ambient temperature
Output signal and communication protocol
Power supply, electrical connection and housing option
Diaphragm seals, capillaries and accessories
Hazardous-area, hygienic-process and safety approvals
A similar model name does not establish technical equivalence. When replacing an older instrument with a newer model, process connections, pressure capability, measurement range, communication and certification requirements must be compared individually.
For Deltabar products, providing technical information together with commercial requirements helps support an accurate quotation process.
Where possible, include the following information in the RFQ (Request for Quotation):
Requested model and complete order code, if available
Instrument nameplate or photograph
Datasheet and technical specification
Measurement range, process pressure and temperature
Fluid information and material requirements
Process connection and installation arrangement
Output signal and communication requirements
Required certifications and safety approvals
Quantity and project delivery requirements
Yeşil Grup Enerji can support industrial sourcing processes through order-code verification, technical configuration review, datasheet assessment, alternative-product research and project-specific quotation support. Product suitability, availability and delivery time are assessed according to the requested configuration and supplier confirmation.
Deltabar measures the pressure difference between two points. With a suitable instrument, installation and calculation method, the differential pressure can also be used for level or flow measurement.
PMD50 is designed for standard differential pressure, level and flow applications. PMD63B is particularly relevant for low differential pressure measurement under high static pressure and more advanced process requirements. Final selection depends on measurement range, communication, connections and process conditions.
The manufacturer's product page specifies accuracy up to 0.05% for the standard option and up to 0.035% for the Platinum option. These values must be interpreted in the context of the selected configuration and the manufacturer's specified reference conditions.
With a suitable diaphragm-seal configuration, the manufacturer specifies process temperatures up to 400 °C. This limit does not automatically apply to every connection and configuration; the complete order code and technical documentation must be verified.
Yes. Flow can be calculated from the differential pressure generated by a suitable primary element, such as an orifice plate. Accurate measurement also requires appropriate primary-element design, fluid data and signal scaling.
A replacement may be possible, but direct compatibility should not be assumed. The complete order code, measurement range, static pressure, process connections, materials, electrical properties and certifications must be compared.
The model or complete order code, instrument nameplate, datasheet, process conditions, connection details, communication requirements and required certifications help determine the appropriate product configuration.
Selecting the right Endress+Hauser Deltabar model requires a combined assessment of differential pressure range, static line pressure, temperature, materials, connections, communication and application requirements.
PMD50 can be considered for standard applications. PMD63B is relevant to low DP measurement under high static pressure and advanced process integration. PMD75B offers options for higher measurement performance and diagnostic functions, while PMD78B provides high-temperature solutions with suitable diaphragm-seal configurations. FMD71/FMD72 use a different system architecture for level measurement using electronic differential pressure.
Before purchasing or replacing an instrument, verify the current manufacturer documentation and the complete order code. This helps reduce the risk of incorrect configuration, connection incompatibility and operation outside permitted process limits.
Yeşil Grup Enerji is not an official distributor or authorized representative of Endress+Hauser. As an independent, brand-independent industrial supplier, we can support global sourcing research, complete order-code verification, technical configuration review, datasheet assessment, alternative-product research and project-specific quotation requests for Deltabar products.
When submitting a quotation request, please provide the existing instrument's nameplate, complete order code, technical documentation and process requirements. Technical suitability and commercial terms are evaluated according to the requested configuration and supplier confirmation.
Contact Information
Email: [email protected]
Phone: +90 505 696 61 00
Website: https://www.yesilgrupenerji.com/
Target markets: Project-based sourcing requests can be evaluated from Türkiye and the Middle East, Europe, the CIS and Central Asia, Africa, Asia and the Americas.