In brief
A pressure sensor, also called a pressure transmitter, detects the pressure of gases or liquids and converts it into an electrical measuring signal.
Contents
What is Pressure sensor?
Pressure sensors measure pressure in hydraulic and pneumatic systems, pipelines, vessels or pump installations. A sensing element, such as a diaphragm with strain gauges, a piezoresistive chip or a ceramic measuring cell, deforms under pressure; the electronics convert this change into a signal. A pressure transmitter delivers a standardised signal such as 4–20 mA, while a pressure switch switches at a set value. It often replaces or supplements a pressure gauge when the reading needs to be sent to a control system.
A distinction is made between gauge, absolute and differential pressure measurement. Key ratings are measuring range, overload and burst pressure, accuracy, output signal, process connection (thread or flange), materials of wetted parts, media and ambient temperature, electrical connection and degree of protection. For potentially explosive atmospheres there are versions with ATEX marking, and for food applications there are hygienic connections.
Failures are frequently caused by pressure peaks, cavitation, aggressive media, vibration or moisture in the electronics. A replacement unit must match the measuring range, signal and process connection exactly. Pressure peaks can be reduced with restrictors or damping elements in the connection. For safety-relevant or quality-critical measuring points, regular calibration is part of maintenance.
In practice: maintenance and procurement
For an enquiry, the manufacturer part number, measuring range, pressure type, output signal, process connection, medium, temperature range and electrical connection are needed. In hazardous areas, the ignition protection marking must also match.
Synonyms and abbreviations: pressure transmitter · pressure transducer · pressure measuring transducer · pressure sensing element
Frequently asked questions
What is the difference between a pressure sensor and a pressure transmitter?
In everyday usage, the two terms are often used interchangeably. Strictly speaking, the pressure sensor is the sensing element that converts pressure into an electrical quantity. The pressure transmitter also contains the electronics that turn this into a standardised, interference-resistant signal such as 4–20 mA and transmit it to the control system.
What do gauge pressure, absolute pressure and differential pressure mean?
Gauge pressure is measured relative to the current ambient air pressure and is the most common in plants. Absolute pressure uses vacuum as its zero point. Differential pressure is the difference between two measuring points, for example upstream and downstream of a filter, to monitor how clogged it is.
What information is needed to replace a pressure sensor?
The manufacturer part number, measuring range, pressure type, output signal, supply voltage, process connection with thread type, material of wetted parts, medium, temperature range, electrical connection and degree of protection are needed. For measurements in potentially explosive atmospheres, the Ex marking is mandatory; for food applications, details of the hygienic process connection are also required.