PCB Piezotronics IMI SENSORS HT622B01 Installation And Operating Manual page 23

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Name
Safe Detected failure rate
Safe Undetected failure rate
Dangerous Detected failure rate
Dangerous Undetected failure rate
Average frequency of a dangerous
failure on demand
Result
?.SDX
10 6
0.021
Xsux10 6 0.014
XDDXIO 6
0.029
?.ux10 6
0.018
PFHx 10 6
0.018
Type B components: 62X Series
The safety relevant parameter PFD avg is in compliance with the corresponding requirements for SIL 2
according to IEC 615081. If this sensor Is fully defined as type B, then the SIL capability is SIL 1 because the
SFF is 78.18 %. However, If this sensor is fully defined as type A, then the SIL capability is SIL 2. According to
IEC 61508-2 section 7.4,4.2.3 if the sensor has both type A and type B, then SFF may fall below 90% with
HFT of "0" and can be considered to have SIL 2 capability. Even though PFDavg has the range of SIL 4, the
hardware fault tolerance limits the capability to SIL 2. The user should consider, that the hardware fault
tolerance of all inspected devices is zero and that a single fault can lead to a dangerous failure.
Senior Consultant,
4-7' - - -
Ashton Hainge, lntertek
Certified Functional Safety Professional (CFSP)
1
The assessment results described in this report only refer to the safety-related parameters PFD avg, HFT, and SFF
according to IEC 61508.
This report does not make any statements, that the manufacturer meets all other requirements of the above cited
standards for hardware, software, documentation, management of functional safety, verification, and validation.
This report does not Imply that the examined pressure sensors have been certified for functional safety by the assessor
according to IEC 61508 or any other standards.
The sensors are only one part of a complete safety function. It is at the responsibility of the end-user to prepare and to
apply an extensive reliability model, that brings out the complete safety function and that meets all requirements of
the claimed SIL level according to IEC 61508.
PCB SIL Sensor Rating
Report No: 103685042CS11002
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