Absolute and Gauge Pressure

Absolute and Gauge Pressure

Absolute and gauge pressure measurement includes continuous pressure transmitters and pressure switches that monitor liquids, gases, and steam either relative to ambient (gauge) or referenced to a perfect vacuum (absolute). The output is typically a standardized signal used for monitoring and control, with instruments selected to balance accuracy, response time, and durability in the installed environment.

Endress+Hauser positions this category around Cerabar pressure sensors and Ceraphant pressure switches, covering general process services and hygienic duties where pressure devices are also used to infer level. The offering spans ceramic or silicon measuring cells as well as diaphragm seal designs, supporting process and hygienic industries and common certification needs, including hygienic approvals plus functional safety (SIL) and explosion protection where required.

A typical transmitter implementation uses a silicon cell: process pressure deflects a process‑isolating diaphragm, a fill fluid transfers that pressure to a resistance bridge, and the resulting bridge output change is measured and evaluated. Pressure switches provide discrete setpoint action by opening or closing a PNP contact at the set pressure, and can also provide a 4–20 mA output for continuous indication.

Benefits come from matching sensing technology to operating extremes and installation constraints. Silicon cell designs are described for process pressures up to 700 bar, small flush-mount process connections, overload resistance, and minimal thermal effects. Diaphragm seals add special materials and process connections and extend usable process temperatures from –70 to +400 °C. Pressure switches support local function checks and on-site information with LEDs and a digital display; operation and visualization are also possible via PC, with stainless steel housing and a lasered nameplate.

Typical applications include pump and compressor protection, header and reactor pressure control, vacuum and inerting/blanketing measurements, steam and utility pressure supervision, and pressure-based level indication in vessels. Hygienic configurations support cleanable installations in food and beverage, while seal systems and material options address corrosive media, high temperatures, and connection limitations in harsh services.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.