| Warning patterns |
Consider
the example of a tank used for some chemical processing, with sensors for
temperature, pressure and PH. The result of hazard analysis may indicate that
leakage from one of the valves should raise the temperature and pressure and
lower the PH. If the save valve is stuck closed, the temperature should raise
and the pressure and PH should get lower values. Similar data, with different
results, may be obtained about other valves. If the tank leaks, the temperature
and pressure may decrease and the PH would remain unchanged. What we get is a
map of trends in sensor data due to hazards. We can use this map at run time to
direct the operator to the source of warning messages. |