Methods of On-Line Detection

The On-Line Warning System (OLIWA) has been described [225] it was introduced into the United States in 1986 [226]. Another detailed description is in [227]. 

Off-line measurements differ significantly from on-line techniques. Offline measurements include safety testing in a laboratory, which has the major advantage of providing available time to redesign the process and/or equipment if a risk is identified. Of course, immediate process response is not possible. 

The most important on-line methods are discussed below along with the hazard criteria used by each technique. 

Measuring a single variable and checking against a preselected value— 

The temperature hazard criterion is defined as the point at which the system temperature exceeds a specified value, or  

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