REMOTELY PROOF-TESTING TO IMPROVE SIS PERFORMANCE

摘要

Periodic proof-tests are a necessity for level switches that form part of a safety instrumented system (SIS) and partial proof-tests provide a safe way to optimise the time interval between full tests. Marianne Williams compares different ways of performing partial proof-tests. The remote partial proof-testing - capability of the latest vibrating fork level detectors can enable full proof-test intervals to be safely extended to up to ten years, providing the freedom to schedule tests around planned shutdowns. While solutions using external switching units provide a means of remotely initiating partial proof-tests, this method involves various extra complexities. In contrast, the latest generation of vibrating fork level detectors, with integrated remote proof-testing functionality, are less complex.