Useful Lifetime; Support For Sil-Approved Devices - Siemens SITRANS F Additional Operating Instructions

SITRANS FX330

5.6 Useful lifetime

The established failure rates of electronic components apply within the useful lifetime according
to IEC 61508-2, section 7.4.9.5 note 3.
The useful lifetime can only be extended under responsibility of the plant operator regarding
special operation conditions and the employment of suitable intervals for testing and
maintenance.
As a consequence for the safety function, the total failure rate, and consequently λ
be assumed as constant at the end of the life time. The following table provides an overview
about the downgrade of lifetime, depending on electronic temperature which is the most lifetime
reducing factor.
Non-Ex/Ex i [IS]
Profile
1
2
3
Ex d/Ex t/Ex nA [XP/DIP/NI]
Profile
1
2
3
1 The expected lifetime is defined here as time interval wherein less than 15% of all devices
failed.
2 For low demand applications for a tolerated residual failure probability of 0.0003 per demand.

5.7 Support for SIL-approved devices

All instruments which are unlocked for the use in a SIL mode are registered by the
manufacturer.
In case that modifications at the supplied flowmeter will be necessary which are relevant to the
safety function of the device, the manufacturer will inform the customer immediately.
10/2017 - A5E40875009-AB EN
λ
Temperature
DU
[°C / °F]
[/h]
40 / 104
4.64 * 10
60 / 140
9.79 * 10
80 / 176
2.13 * 10
λ
Temperature
DU
[°C / °F]
[/h]
40 / 104
4.72 * 10
60 / 140
9.98 * 10
80 / 176
2.17 * 10
Reduction of
Reliability to
[%]
-8
-8 47
22
-7
Reduction of
Reliability to
[%]
-8
47
-8
22
-7
www.siemens.com/flow
TECHNICAL DATA
DU
Exp. Lifetime 1 Recommended
[years] Proof Test
Interval 2
[years]
11.5 12
6 6
3 2
Exp. Lifetime 1 Recommended
[years] Proof Test
Interval 2
[years]
11.5 12
6 6
3 2
5
must not
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