MEDC PBE Manuel Technique page 9

ssessment of Functional Safety
The BG Call Point is intended for use in a safety system conforming to the requirements of IEC61508.
Sira Test & certification Ltd has conducted a Failure Modes Effect and Diagnostic nalysis (FMED ) of
the BG Break Glass unit against the requirements of IEC61508-2 using a proof test interval of 8760hrs.
The Call Point is classed as a Type
Architectural constraints:
Random hardware failures:
Probability of failure on demand:
Probability of Dangerous failure on
safety function:
Hardware safety integrity compliance
Systematic safety integrity compliance
Systematic Capability
Overall SIL-capability achieved
11/13
device.
BG BREAKGLASS UNIT
Safety Function of BG Break Glass Unit:
'To raise the alarm upon breaking the glass'
Type A
HFT=0
SFF= 97%
= 0
DD
= 5.72E-07
DU
PFD =2.51E-03
AVG
(Low Demand Mode)
PFH = 5.72E-07
(High Demand Mode)
[1]
Proof Test Interval
=8760Hrs
MTTR = 8 Hrs
= 0
SD
= 2.04E-05
SU
SIL2
SIL2
Route 1
H
Route 1
S
SC2
SIL 2 (Low Demand)
SIL 2 (High Demand)
SIL3
© MEDC 2013