In 1681, the first pressure relief valve was designed by Denis Pepin to keep his experimental steam chamber from exploding. The idea was simple, rather than using an external system, use the process’ power as the safety operator.
In 1931, when the modern rupture disc was invented using the tensile strength of various materials to provide both barrier and relief if things went wrong. That same year, United Electric Controls connected metal bellows to the snap-action electric switch they had just invented and the modern pressure switch was born. Like the pressure relief valve and the rupture disc, it is simple; pressure converted to mechanical motion that then becomes an electrical output. It is the most basic combination of a sensor and logic solver, and one that does not require external power to operate or software to run.
Since their invention, these various types of technology are continually incorporated into most pressurized vessels throughout the world. Why?
This is because even when we design the most accurate and reliable control and safety systems known to man, things can still go wrong. Power outages, design flaws, failed battery back-ups, or human error – all are potential causes for an unwanted event. Your last line of defense? The mechanical device! Because the trust in these simple technologies is widespread – we hardly notice that they are even there, but they are always ready to act.
One issue that is bringing these technologies back to the forefront of people’s minds these days is cybersecurity. The consensus seems to be there are no methods that can fully protect a software-based system. Ease of use and the promise of interconnected devices and systems delivering more data has also increased the potential to allow a bad actor to breach software security. Those threats can come from a single dissatisfied person, or a nation-state looking to cause infrastructure disruption.
Recognizing the potential for equipment and processes to be tricked into an unsafe state, there has been an increased focus on robust systems protected with layers of defense. Smart designers are remembering Occam’s Razor, that the simple solution is most likely the best. And reliable mechanical devices are right there, waiting to be called upon.
About the Author:
Ken Kirkwood, Vice President of Sales
Ken has more than 35 years of experience working with industrial instrumentation, focused on keeping people and processes safe.