Sil Capability; Safety Function; Failure Rates - Fisher Fieldvue DLC3100 Safety Manual

Instruction Manual Supplement
D104215X012

SIL Capability

D Systematic Integrity
SIL 2 Capable – The DLC3100 SIS digital level controller has met manufacturer design process requirements of
IEC61508 Safety Integrity Level 2.
D Random Integrity
The DLC3100 SIS digital level controller is classified as a Type B device according to IEC61508. The complete
element subsystem will need to be evaluated to determine the SFF. If the SFF of the subsystem is > 90% and
the PFD < 10
avg
and the PFD
avg

Safety Function

The safety function of DLC3100 SIS digital level controller is to measure level or interface of fluids and transmit a
4-20 mA analog signal within the safety accuracy (measurement accuracy ±2%). It includes the whole hardware and
software measurement chain from the displacer through the torque tube and the electronic board to the primary
analog output signal.
Table 5. Normal and Alarm States for FIELDVUE DLC3100 SIS Digital Level Controller
Output Function
4-20 mA
Level transmitter
1. Configurable high or low. Values are per NAMUR NE43.

Failure Rates

The failure rate data listed in table 6 and 7 is valid for the 15-year useful lifetime of the DLC3100 SIS digital level
controller. Its useful lifetime is highly dependent on the subsystem itself and its operating conditions. The failure rate
will increase after this time period. Reliability calculations based on the data listed in the FMEDA report for mission
times beyond the useful lifetime may yield results that are too optimistic.
Table 6. Failure Rates for FIELDVUE DLC3100 SIS Digital Level Controller
Failure Category
Fail Safe Detected, λ
SD
Fail Safe Undetected, λ
Fail Dangerous Detected, λ
Fail Detected (detected by internal diagnostics)
Fail High (detected by logic solver)
Fail Low (detected by logic solver)
Fail Dangerous Undetected, λ
No Effect
Annunciation Detected
Annunciation Undetected
SFF
-2
, the design can meet SIL2 @ HFT = 0. If the SFF of the subsystem is between 60% and 90%,
-1
< 10 , the design can meet SIL1 @ HFT = 0.
Normal State Safety Accuracy
Actual fluid level
SU
DD
DU
±2% >21.0 mA or <3.6 mA
Failure Rate (FIT)
0
0
463
230
83
150
39
186
33
14
92.2%
DLC3100 SIS Digital Level Controller
(1)
Alarm State
April 2018
7