Some pressure sensors are specifically designed to work with corrosive, aggressive or highly contaminated liquids and gases, collectively known as “corrosive media”. These corrosive substances will destroy or damage other substances that they come into contact with, including metals and organic compounds. This makes them difficult and dangerous to work with and raises unique challenges for the design of pressure sensors with corrosive media compatibility.
Pressure sensors for corrosive media are used in applications such as industrial measurement and control, industrial boilers, monitoring the levels of chemical storage tanks, waste management, medical devices, instrumentation and analytical devices.
They also find applications in energy technologies such as those using natural gas, biogas, landfill gas and CHP (combined heat and power).
Pressure sensors for corrosive media usually measure pressure in one of two ways: absolute or gauge. Absolute pressure is measured relative to a particular value, such as zero or atmospheric pressure at sea level. With this method, the reading is always the same, regardless of where the unit is located. Gauge pressure sensor is measured relative to the surrounding atmosphere, meaning that readings can vary based on location and altitude.
Pressure sensors for corrosive media are transducers, generating an electrical signal in proportion to the pressure they measure. This allows pressure to be monitored by various devices with a suitable interface. Most pressure sensors for use with corrosive media use the principle of piezoresistance. The sensor is based around a diaphragm made from a ceramic material that’s elastic but resistant to corrosion and abrasion.
Options and Specifications
Pressure sensors for use with corrosive media often feature housings made from stainless steel or plastics such as PVDF or PVC. The sensor elements themselves are typically ceramic, although some sensors use a stainless steel diaphragm backed by silicon oil that transfers pressure to the sensing element.
The pressure sensors will usually specify a suitable pressure range. Certain sensors may be able to measure both absolute and gauge pressure (see above), with a pressure range specified for each. Some sensors can be configured to measure negative pressure as well as positive.