Spurious Trip Level - STL Determination

STL Determination

The spurious trip level represents asset loss due to an internal failure of the safety function. The more financial damage the safety function can cause due to a spurious trip the higher the STL level of the safety function should be. Each company needs to decide for themselves which level of financial loss they can or are willing to take. This actually depends on many different factors, like the financial situation of the company, the insurance policy, the cost of process shutdown and startup, and so on. All these factors are unique to each company. The table below shows an example of how a company can calibrate its spurious trip levels.