Page 466 - Offshore Electrical Engineering Manual

Safeguards 453

PFD (SV)

+

87600
0 1 2 3 4
78840

70080

61320

52560 2.63·10 −2 . 2oo4, 2-out-of-4; FWP, fire-water pump; HFT, hardware fault tolerance; MTTR, mean time to repair; SIL, safety integ-

43800 Interval between Proof Tests (h) Comments: The PFD for ventilation dampers and associated solenoid valves were taken from the SIL Verification Report and accepted as adequate

35040 26280 for the modelling. These were then added together as one block modelling the fire damper. PFD of block was then found to be PFD (FD)
PFD according to proof test interval (h): 17520 8760 0 rity level; PFD, probability of failure on demand; SFF, safe failure fraction. ORBIT SIL Printouts courtesy of Dr Luiz Fernando Oliveira, DNV-GL Brazil.

1x10 +0
1x10 -1
1x10 -2
1x10 -4
1x10 -3
1x10 -5
PFD
=
4.3·10 −3
+
2.2·10 −2

=