An FMEDA Report by Exida has
shown the Netherlocks Partial Stroke
System to meet SIL 3. The report
showed the FAITH (Fail Action
Integrity Test Handling) system to be
very reliable, with 0 Fail Safe
Detected, Fail Safe Undetected and
Fail Dangerous Detected conditions
recorded from the tests. For most
cases, the FAITH is suitable for use in
SIL3 applications.

The FAITH system makes it
possible to carry out a manuallyinitiated
partial stroke test on ESD
(Emergency Shut Down) valves
during normal operation, without
interrupting process flow. It limits,
with mechanical stops, the angle of
the stroke of the valve-actuator
combination to a set percentage –
ensuring the ESD valve ‘works’,
without actually shutting down the
operation.