Measuring Performance
For shutdown valves used in safety instrumented systems it is essential to know that the valve is capable of providing the required level of safety performance and that the valve will operate on demand. The required level of performance is dicated by the Safety integrity level (SIL). In order to adhere to this level of performance it is necessary to test the valve. There are 2 types of testing methods available being
- Proof test - A manual test that that allows the operator to determine whether the valve is in the "as good as new" condition by testing for all possible failure modes and requires a plant shutdown
- Diagnostic Test - An automated on-line test that will detect a percentage of the possible failure modes of the shudown valve. An example of this for a shutdown valve would be a partial stroke test
Read more about this topic: Shut Down Valve
Famous quotes containing the words measuring and/or performance:
“We recognize caste in dogs because we rank ourselves by the familiar dog system, a ladderlike social arrangement wherein one individual outranks all others, the next outranks all but the first, and so on down the hierarchy. But the cat system is more like a wheel, with a high-ranking cat at the hub and the others arranged around the rim, all reluctantly acknowledging the superiority of the despot but not necessarily measuring themselves against one another.”
—Elizabeth Marshall Thomas. “Strong and Sensitive Cats,” Atlantic Monthly (July 1994)
“The child to be concerned about is the one who is actively unhappy, [in school].... In the long run, a child’s emotional development has a far greater impact on his life than his school performance or the curriculum’s richness, so it is wise to do everything possible to change a situation in which a child is suffering excessively.”
—Dorothy H. Cohen (20th century)