Fisher ET - Manual (Page 5)

ED, ET, EZ, HP, HPA Valves w/ 657/667 Actuator
SIL Safety Manual
July 2010
5
user or diverse technology redundancy in the
design.
Random Integrity
The ED, ET, EZ, HP, or HPA valves are classified as
Type A devices according to IEC 61508, having a
hardware fault tolerance of 0. The complete final
element subsystem, with a Fisher valve as the final
control element, will need to be evaluated to
determine the Safe Failure Fraction of the
subsystem. If the SFF for the entire final element
subsystem is between 60% and 90%, a design can
meet SIL 2 @ HFT=0.
Safety Parameters
For detailed failure rate information refer to the
Failure Modes, Effects and Diagnostic Analysis
Report for the ED, ET, EZ, HP, or HPA valve.
Connection of the Fisher ED, ET, EZ,
HP, or HPA Valve to the SIS
Logic
-solver
The final element subsystem (consisting of a
positioner, actuator, and ED, ET, EZ, HP, or HPA
valve) is connected to the safety rated logic solver
which is actively performing the Safety Function as
well as any automatic diagnostics designed to
diagnose potentially dangerous failures within the
ED, ET, EZ, HP, or HPA valve , actuator and any
other final element components, (i.e. Partial Valve
Stroke Test).
General Requirements
The system’s response time shall be less than
process safety time. The final control element
subsystem needs to be sized properly to assure that
the response time is less than the required process
safety time. The ED, ET, EZ, HP, or HPA valve will
move to its safe state in less than the required SIF’s
safety time under the specified conditions.
All SIS components including the ED, ET, EZ, HP, or
HPA valve must be operational before process
start-up.
The user shall verify that the ED, ET, EZ, HP, or
HPA valve is suitable for use in safety applications.
Personnel performing maintenance and testing on
the ED, ET, EZ, HP, or HPA valve shall be
competent to do so.
Results from the proof tests shall be recorded and
reviewed periodically.
The useful life of the ED, ET, EZ, HP, or HPA valve
is discussed in the Failure Modes, Effects and
Diagnostic Analysis Report for the Fisher ED, ET,
EZ, HP, or HPA valve.
Installation and Commissioning
Installation
The Fisher ED, ET, EZ, HP, or HPA valve must be
installed per standard practices outlined in the
appropriate instruction manual.
The environment must be checked to verify that
environmental conditions do not exceed the ratings.
The ED, ET, EZ, HP, or HPA valve must be
accessible for physical inspection.
Table 1. Recommended Full Stroke Proof Test
Step Action
1 Bypass the safety function and take appropriate action to avoid a false trip.
2 Interrupt or change the signal/supply to the actuator to force the actuator and valve to perform a full stroke to the Fail-Safe state and
confirm that the Safe State was achieved and within the correct time.
3 Restore the supply/signal to the actuator and confirm that the normal operating state was achieved.
4 Inspect the ED, ET, EZ, HP, or HPA valve and the other final control element components for any leaks, visible damage or
contamination.
5 Record the test results and any failures in your company’s SIF inspection database.
6 Remove the bypass and restore normal operation.