Woodward Large Electric Sonic Valve II, Инструкция по установке и эксплуатации, Страница: 55 / 66

Manual 35076 LESV II
Woodward 53
Chapter 7.
Safety Management – Position Feedback
Light-Off Function Flow Sensor
Product Variations Certified
The SIL rated LESV (also known as LESV–Flow Sensor) is designed and certified to the functional safety
standards according to IEC61508, Parts 1 through 7. Reference the product
FMEDA: WOO 17/07-039 R002 and Certificate: WOO 1707039 C002.
The functional safety requirements in this chapter apply to all LESVs that have a SIL-rated position
sensor installed (see table below).
The LESV II – Flow Sensor is intended for use in applications at a SIL2 system level according to
IEC61508, and is capable of SIL3 when implemented with appropriate system redundancies.
The LESV–Flow Sensor is designed and verified to withstand the worst-case (or greater) expected
environmental conditions as listed in other sections of this manual.
Covered LESV Versions
The table below identifies the LESVs that are SIL certified for the light-off function.
Table 7-1. SIL Certified LESVs
Valve Part
Number
Flow
Function
SIL Level
Valve Shut-
off Function
SIL Level*
Valve Cg
Flange
Rating
(pounds)
Valve
Size
(inches)
9904-3440 Yes Yes 2500 600 3
9904-3441 Yes Yes 3655 600 4
9904-3442 Yes Yes 6600 600 6
9904-3463 Yes Yes 2500 600 3
9904-3464 Yes Yes 3655 600 4
9904-3465 Yes Yes 6600 600 6
*Note: For more detail in the shutoff SIF, see chapter 6
The LESV II – Flow Sensor is only one part of a sensor subsystem that supports the entire Light-Off SIF.
The LESV II – Flow Sensor provides mechanical position feedback of the valve plug position. An accurate
feedback device such as the MTS Temposonics position sensor must be used in order to produce the
position signal. Accurate valve position feedback can be used as one of the inputs to calculate the flow
through the LESV II.
SFF
=
λ
DU
/
λ
TOTAL
Where
λ
TOTAL
=
λ
SD
+
λ
SU
+
λ
DD
+
λ
DU
The failure rates listed below, for only the LESV–Flow Sensor, do not include failures due to wear-out of
any components. They reflect random failures and include failures due to external events such as
unexpected use. Reference the FMEDA: WOO 17/07-039 R002 for detailed information concerning the
SFF and PDF.
The failure rates listed below apply to the LESV II – Flow Sensor mechanical positioning aspect of the
system, and do not include the failure rates of the MTS Temposonics position sensor. Refer to MTS
safety manual 551504 for failure rates of the position sensor.
Released