Differential Pressure Transducers

Differential pressure transducers, while similar to standard pressure transmitters, focus on measuring the difference in pressure between two points in a fluid or gas system. They don't provide absolute pressure readings but rather the variation between two pressures. Here's a breakdown of their typical specifications:

General Specifications

· Differential Pressure Range: This specifies the range of pressure difference the transducer can measure (e.g., ±100 Pa, -10 to +10 bar).

· Accuracy: Expressed as a percentage of full scale (%FS) similar to standard transmitters. Typical accuracy for good quality models is ±0.5%FS to ±2%FS.

· Output Signal: The most common output signal is a 4-20mA current loop, but 0-5V or 0-10V voltage outputs can also be found.

· Supply Voltage: The voltage required to power the transducer (typically 24VDC).

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Performance Specifications

· Temperature Limits: The operating temperature range the transducer can withstand.

· Static Pressure Rating: The maximum pressure each individual input port can handle without damage (important because differential transducers have two pressure inputs). This can be higher than the differential pressure range.

· Proof Pressure: The maximum overall pressure the transducer can withstand without permanent damage (typically 1.5 to 2 times the upper limit of the differential pressure range).

· Burst Pressure: The pressure that will cause catastrophic failure (typically 4 times the upper limit of the differential pressure range).

· Response Time: The time it takes for the output to respond to a change in pressure difference (usually in milliseconds).

Environmental Specifications

· Ingress Protection (IP rating): Similar to other transmitters, this rating indicates the level of protection against dust and water ingress (e.g., IP65 for dust tight and water jets).

· Material of Construction: The materials used in wetted parts (those coming into contact with the process fluid) are crucial. Common materials include stainless steel, Hastelloy C, and Monel.
 

Additional Features

· Media Compatibility: The type of fluids or gases the transducer is compatible with, considering factors like corrosiveness.

· Communication Protocol (Optional): Some advanced models offer communication protocols like HART for remote configuration and diagnostics.

· Display (Optional): Some transducers may have a built-in display for local pressure difference reading.

· Calibration: Calibration is necessary to ensure accuracy. Some models offer features like zero and span adjustments for easier calibration.

Factors to Consider When Selecting a Differential Pressure Transducer

· Process Connections: The type of fitting used for connecting the transducer to the two pressure points (e.g., NPT, flange).

· Electrical Connections: The type of electrical connector for power and output signal.

· Fluid Compatibility: Ensure the materials and media compatibility specifications match the fluids in your application.

By understanding these differential pressure transducer specifications and additional factors, you can select a suitable model for your specific application that requires measuring pressure differences in liquids or gases.