Pressure Transducers
Pressure Transducers for Industrial Process Measurement
Pressure transducers convert a process pressure into a continuous analog output signal proportional to the measured value, feeding controllers, PLCs, and data acquisition systems within Galco's broader transducers category. The first selection decision is measurement reference type, which defines what the transducer is actually measuring. Gauge pressure transducers measure pressure relative to local atmosphere and are the standard choice for most industrial process applications including hydraulics, pneumatics, and pump monitoring. Absolute pressure transducers measure relative to a perfect vacuum and are required where atmospheric pressure variations would affect accuracy, such as altitude-sensitive applications or vacuum monitoring. Differential transducers have two process ports and measure the difference between them, used for filter monitoring, flow measurement across an orifice, and level measurement in pressurized tanks.
Pressure range must be selected carefully. The transducer's full-scale range should cover the maximum process pressure including surge conditions, but overly wide ranges reduce resolution across the normal operating band - the same accuracy class applied to a wider span produces a larger absolute error at any given reading. Output signal must match the receiving instrument: 4-20mA is standard for most industrial PLC and DCS inputs due to its noise immunity and loop-powered two-wire option; 0-10V is common for shorter runs and some controllers. Process connection type and wetted material selection depend on the media being measured - stainless steel construction suits most liquid and gas applications, but aggressive media, high-purity processes, or sanitary applications may require specific alloys, coatings, or diaphragm materials confirmed against a chemical compatibility reference.
For force measurement applications requiring a transducer rather than a pressure device, see Galco's force transducers. For signal conversion and conditioning between transducer outputs and control system inputs, signal transducers cover isolation, scaling, and protocol conversion requirements.
Frequently Asked Questions
What is the difference between gauge and absolute pressure, and how do I know which I need?
Gauge pressure is measured relative to current atmospheric pressure - a gauge transducer reads zero at atmospheric conditions regardless of altitude or barometric variation. Absolute pressure is measured relative to a perfect vacuum, so atmospheric pressure reads approximately 14.7 PSIA at sea level. Most industrial process applications use gauge measurement. Absolute is required when atmospheric pressure variation would affect the measurement, or when monitoring vacuum levels where gauge measurement would produce negative values the transducer isn't designed to handle.
Why does overpressure rating matter separately from the measurement range?
A transducer's measurement range defines where it produces an accurate, linear output. Its overpressure rating defines how far above that range the sensing element can be pressurized without permanent damage or calibration shift. Process systems with pressure spikes, surge events, or valve slam can momentarily exceed the measurement range significantly. Selecting a transducer whose overpressure rating does not cover realistic surge conditions risks permanent sensor damage even if the normal operating pressure is well within range.
Can I use a pressure transducer to measure viscous or slurry media?
Standard pressure transducers with direct process port connections can foul or clog when measuring viscous fluids, slurries, or media with suspended solids, which block the port and prevent accurate pressure transmission to the sensing element. Flush diaphragm or remote seal configurations eliminate the recessed port, placing a flat diaphragm flush with the process connection so media contacts only the diaphragm face rather than entering a cavity. Confirming media compatibility with both the diaphragm material and any wetted components is required regardless of port configuration.