Indicator October 2017

Few things are as ubiquitous in the process control industry as the need to measure the level of a process material in a container. Whether that material is water, waste water, petroleum, sugar, or any other form of liquid or solid, level measurement accuracy can be a determining factor in both profit margins and safety. On December 11th 2005, malfunctioning level gauges were partially responsible for a massive explosion at the Hertfordshire Oil Storage Terminal in Hertfordshire, England. According to the Health and Safety Executive that investigated the blast, "the tank was full, but gauges and safety devices did not work."¹ A high level switch that should have detected the petrol level and cut off flow to the tank failed to operate and workers didn't notice that the tank was overflowing.² This resulted in a 32-hour inferno which injured 43 people and left many families homeless.