Absolute and Gauge Pressure

Absolute and Gauge Pressure

Absolute and gauge pressure measurement covers continuous indication and switching of process pressure referenced either to atmosphere (gauge) or to a sealed vacuum reference (absolute). It supports equipment protection, control stability, and derived indications such as hydrostatic head-based level. Endress+Hauser positions Cerabar pressure transmitters and Ceraphant pressure switches as fit‑for‑purpose options spanning hygienic and general process services.

Measurement performance is largely defined by the sensing cell and the process isolation concept. Silicon‑cell designs use a process‑isolating diaphragm and fill fluid to transfer pressure to a resistance bridge, converting diaphragm deflection into an electrical signal. Ceramic, oil‑free capacitive cells add strong media compatibility, while diaphragm seals extend pressure measurement to challenging connections, aggressive chemistry, or extreme temperatures.

Key benefits show up as stability and survivability in demanding conditions. Silicon cells support very high process pressures with overload resistance and minimal thermal effects, helping preserve accuracy through temperature swings and transients. Diaphragm seal variants broaden wetted‑material and process‑connection choices and allow operation from roughly −70 to +400 °C, expanding where pressure can be measured directly without compromising the sensor.

Pressure switches complement transmitters when a discrete action is required at a setpoint. A switch can open or close an electrical PNP contact when the set pressure is reached, and variants may also provide a 4–20 mA output for trending. Local LEDs and a digital display support functional checks and on‑site status confirmation, with additional configuration and visualization possible via a PC.

Typical applications include pump and compressor suction/discharge monitoring, header and line pressure control, reactor and vessel pressure tracking, and utility services such as instrument air, steam, and inert gas distribution. In sanitary processes, hygienic approvals support use where cleanable wetted parts are required. When mounted at a defined elevation, the same devices are routinely used to infer level from hydrostatic head for tanks, sumps, and packaged skids.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.