Pressure sensors can be used in a wide range of applications. Itís imperative that theyíre suited for use in hazardous situations and are fully compliant with one of several protection standards.
The most common solution uses a pressure sensor bearing "Exd" protection, which is commonly referred to as being explosion-proof or flameproof. These transmitters are meant for use within hazardous areas classified as Zone 1(21) or 2(22) according to the ATEX classification and can be used in Class I, II, or III areas in accordance with the North American classification.
An Exd pressure sensor must be enclosed in an explosion-proof casing, so that all of the transmitterís electronic components are housed inside a case that, should any explosion occur inside of it, is designed to prevent any flames from leaving the enclosed space. This ensures that the flames are contained and canít spread to other parts of the system.
An integral part of the design of explosion-proof Exd enclosures is the inclusion of flame paths, which are long, narrow escapes in which burnt gases can cool down upon exiting. This ensures that they are unable to ignite the external, potentially volatile, fuel-air atmosphere. Flame paths must be planned meticulously to ensure that gases are cooled enough before they exit.
Another essential design feature is the casingís depth. The enclosure must be designed such that, should an explosion occur, heat wonít be transferred from within. If the outer casingís temperature is raised, it could reach a level whereby it could ignite any external combustible environment. Therefore, itís vital that the walls are thick enough to prevent this from happening.
With all of these important considerations, I recommend that you source an explosion-proof pressure sensor from a reliable and experienced manufacturer with a history of quality, well-engineered products that will meet all relevant safety standards.
Nick Murden is a keen writer who helps businesses put thoughts into words. He is currently writing for a number of engineering firms around the UK, including TC Fluid Control.