Safety-related characteristics – KROHNE TT 51 SERIES EN User Manual

Page 18

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7

SAFETY-RELATED CHARACTERISTICS

18

TT 51 SERIES

www.krohne.com

09/2010 - 4000869801 - AD TT 51 SIL R01 en

Single TC + Single RTD 2/3w

Single TC + Single RTD 4w

Failure category

SFF PFD

avg

at T

proof

=

PFH

SIL AC

λ

SD

λ

SU

λ

DD

λ

DU

[FIT]

[%]

1 year

2 years

5 years

10 years

Close

coupled low

stress

0

146 535

41

94.3

2.09E-04

3.86E-04

9.20E-04

1.81E-03

4.10E-08

SIL 2

Close

coupled high

stress

0

146 3334

54

98.4

3.38E-04

5.72E-04

1.27E-03

2.45E-03

5.40E-08

SIL 2

Extension

wires low

stress

0

146 1853

50

97.5

2.83E-04

5.00E-04

1.15E-04

2.23E-03

5.00E-08

SIL 2

Extension

wires high

stress

0

146 29693

235

99.2

1.83E-03

2.85E-03

5.93E-03

1.10E-02

2.35E-07

(SIL 1)

The boxes marked in light grey in the following tables mean that the calculated PFD

avg

and/or

PFH values are within the allowed range for SIL 2 according to table 2 / 3 of IEC 61508-1 but do not
fulfill the requirement to not claim more than 35% of this range, i.e. to be better than or equal to
3.50E-03 respectively 3.50E-07 1/h.
The boxes marked in medium grey mean that the calculated PFD

avg

and PFH values are within the

allowed range for SIL 2 according to table 2 / 3 of IEC 61508-1 and do fulfill the requirement to not
claim more than 35% of this range, i.e. to be better than or equal to 3.50E-03 respectively
3.50E-07 1/h.
The boxes marked in dark grey indicate that the PFD

avg

respectively the PFH values do not fulfill

the requirements for SIL 2 of table 2 / 3 of IEC 61508-1.

Failure category

SFF PFD

avg

at T

proof

=

PFH

SIL AC

λ

SD

λ

SU

λ

DD

λ

DU

[FIT]

[%]

1 year

2 years

5 years

10 years

Close

coupled low

stress

0

146 538

40

94.4

2.04E-04

3.77E-04

8.98E-04

1.76E-03

4.00E-08

SIL 2

Close

coupled high

stress

0

146 3381

48

98.6

3.10E-04

5.18E-04

1.14E-03

2.18E-03

4.80E-08

SIL 2

Extension

wires low

stress

0

146 1883

45

97.8

2.60E-04

4.55E-04

1.04E-03

2.02E-03

4.50E-08

SIL 2

Extension

wires high

stress

0

146 30283

145

99.5

1.42E-03

2.05E-03

3.93E-03

7.08E-03

1.45E-07

(SIL 2)

.book Page 18 Thursday, September 9, 2010 4:19 PM

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