Absolute and Gauge Pressure

Absolute and Gauge Pressure

Absolute and gauge pressure measurement includes field instruments that translate process pressure into a usable signal for indication, control, alarms, and protective logic. Gauge measurement is referenced to ambient pressure; absolute measurement is referenced to a sealed vacuum. Typical devices span pressure transmitters for continuous measurement and pressure switches for discrete setpoints in liquids, gases, and vapors.

A broad portfolio combines silicon and ceramic measuring cells with diaphragm seals that isolate the sensor from corrosive, abrasive, viscous, or hygienic media while enabling many process connection styles. In a silicon-cell design, a process isolating diaphragm deflects with pressure and a fill fluid transfers the force to a resistance bridge for evaluation. Pressure switches open or close an electrical PNP contact at a defined set pressure and may also provide a 4–20 mA output.

Application fit drives the benefits. Silicon-cell instruments support very high pressures with strong overload resistance and low thermal influence, while diaphragm seals expand wetted-material choices and extend operating temperatures into severe service. Switch designs add local LEDs/displays and functional checks for clear status, repeatable setup, and faster fault isolation. Hygienic approvals plus SIL and explosion protection options support standardized deployment in regulated and hazardous environments.

Typical applications include pressure monitoring and control on pumps, compressors, steam and utility systems, reactors, and process headers; vacuum/absolute pressure measurement in drying and evaporation; and pressure-based level or volume inference where hydrostatic head is the controlled variable. Hygienic installations often use flush or cleanable connections for CIP/SIP circuits, filling, and storage.

Successful implementation aligns reference selection (absolute vs. gauge) and range with realistic operating and upset conditions, then optimizes installation details that govern signal quality. Impulse line routing, vibration control, and the choice of diaphragm seals or capillaries can dominate long-term stability. Standard analog and digital interfaces plus built-in diagnostics support integration into PLC/DCS environments and asset management practices.

At Eastern Controls, We are proud to be the exclusive authorized sales and service representative for Endress+Hauser.