Rockwell Automation 1732DS-IB8 User Manual page 118

114 Probability of Failure on Demand (PFD), Probability of Failure per Hour (PFH), and Mean Time Between (MTBF) Data
Publication 1791DS-UM001H-EN-P - April 2009
Calculated Values for Probability of Failure per Hour (PFH) -
1791DS-IB12, 1791DS-IB8XOB8, 1791DS-IB4XOW4
Proof Test Interval 1791DS-IB12
Year Hour
0.25 2190 2.009E-10
0.5 4380 1.999E-10
1 8760 1.994E-10
2 17,520 1.991E-10
Calculated Values for Mean Time Between Failure (MTBF) -
1791DS-IB12, 1791DS-IB8XOB8, 1791DS-IB4XOW4
Model
1791DS-IB12
1791DS-IB8XOB8
1791DS-IB4XOW4
Calculated Values for Probability of Failure on Demand (PFD), Probability of Failure
per Hour (PFH), and Mean Time Between Failure (MTBF) - SIL 3 -
1791DS-IB8XOBV4, 1732DS-IB8XOBV4, 1791DS-IB16
Model Proof Test Interval
Year Hour
1791DS- 1 8760
IB8XOBV4
2 17,520
5 43,800
10 87,600
1732DS- 1 8760
IB8XOBV4
2 17,520
5 43,800
10 87,600
1791DS-IB16 1 8760
2 17520
5 43800
10 87600
1791DS-IB8XOB8 1791DS-IB4XOW4
2.019E-10 4.201E-09
2.004E-10 4.200E-09
1.996E-10 4.199E-09
1.992E-10 4.199E-09
MTBF (hour)
4.02E+05
2.64+05
1.44E+05
PFD PFH
(1/hour)
8.73E-07 2.00E-10
1.75E-06
4.37E-06
8.74E-06
8.73E-07 2.00E-10
1.75E-06
4.37E-06
8.74E-06
8.49E-07 1.94E-10
1.70E-06
4.25E-06
8.50E-06
MTBF
(hour)
2.36E+06
2.36E+06
2.42E+06