Woodward Large Electric Sonic Valve II, Инструкция по установке и эксплуатации, Страница: 56 / 66

Manual 35076 LESV II
Woodward 54
Table 7-2. Failure Rates according to IEC61508 in FIT
Device
λ
SD
λ
SU
²
λ
DD
λ
DU
LESV–Flow Sensor 0 294 0 306
The SFF for the LESV–Flow Sensor supports architectural constraints up through a SIL 2 through the 2
H
Route. The Complete sensor subsystem, of which the LESV–Flow Sensor is a part, will need to be
evaluated to determine the SFF for the subsystem.
When evaluating the sensor subsystem SFF, it should be noted that high temperature fuel flow through
the LESV II may elevate the temperature of the position sensor mounting interface as much as 5°C higher
than the ambient environment of the LESV II. This increase in the position sensor temperature
environment should be considered in the evaluation of the subsystem.
Response Time Data
The LESV, through the SIL rated Position Sensor, provides position information to the safety controller.
There is not a definable, detectable response time for the actuator.
Limitations
When proper installation, maintenance, proof testing, and environmental limitations are observed, the
useful life of the LESV II – Flow Sensor is 48,000 hours of operation. The LESV II can be refurbished and
a product life of 20 years can be achieved.
Management of Functional Safety
The LESV–Flow Sensor is intended for use according to the requirements of a safety lifecycle
management process such as IEC61508 or IEC61511. The safety performance numbers in this chapter
can be used for the evaluation of the overall safety lifecycle.
Restrictions
The user must complete a full functional check of the LESV–Flow Sensor after initial installation, and after
any modification of the overall safety system. No modification shall be made to the LESV–Flow Sensor
unless directed by Woodward. This functional check should include as much of the safety system as
possible, such as sensors, transmitters, actuators, and trip blocks. The results of any functional check
shall be recorded for future review.
The LESV–Flow Sensor must be used within the published specification in this manual.
Competence of Personnel
All personnel involved in the installation and maintenance of the LESV–Flow Sensor must have
appropriate training. Training and guidance materials are included in this manual.
These personnel shall report back to Woodward any failures detected during operation that may impact
functional safety.
Operation and Maintenance Practice
A periodic proof (functional) test of the LESV–Flow Sensor is required to verify that any dangerous faults
not detected by safety controller internal run-time diagnostics are detected. More information is in the
“Proof Test” section below. The frequency of the proof test is determined by the overall safety system
design, of which the LESV–Flow Sensor is part of the safety system. The safety numbers are given in the
following sections to help the system integrator determine the appropriate test interval.
Released