For pressures sensors, if they can’t stand the boiling heat, the freezing cold, corrosive substances, being submerged in salt water, constant exposure to the outside world, they might not be fit for the job.
In other applications, corrosive pressure media can present a threat to sensor components such as the diaphragm, or to the integrity of the sensor as a whole. Commonly encountered media include industrial acids, alkalis, salt water in a marine environment, or even fresh water if the sensor is to be used outdoors or underwater.
Wherever the environment or pressure media are particularly challenging, the chemical compatibility and temperature capability of the sensor are important selection criteria.
- PHYSICAL SEPARATION FROM HAZARDOUS MEDIA
A suitable liquid must be chosen that will not mix with the pressure media, or present risk of contamination to the process being monitored. Heavy industrial oil is often used.
- ISOLATION DIAPHRAGMS FOR HARSH ENVIRONMENTS
Similar principles to the above are applied to create upgraded pressure sensors, capable of withstanding exposure to extreme conditions. An isolation diaphragm can be designed to extend chemical compatibility by using a material such as titanium, tantalum, stainless steel, or another alloy, and filled with a dielectric oil to transfer pressure to the more sensitive diaphragm of the standard sensor. The isolation diaphragm can be an effective barrier to corrosive media or media at a higher temperature than the sensor is able to withstand.
- WITHSTANDING EXTREME TEMPERATURES
- Pressure sensing at extreme temperatures is required in numerous industrial sectors, such as in the petrochemical industry where vast networks of pipelines must be monitored accurately.
- Pipeline pressures must be monitored at locations throughout an entire refining and distribution network that can span extreme climates from near-arctic conditions to desert heat.
- Sensors can be built to operate in various ambient-temperature ranges, with the peak temperature rating of ruggedly designed sensors extending to more than 200°C.