Application Limits; Environmental Limits - Fisher Fieldvue DLC3100 Safety Manual

DLC3100 SIS Digital Level Controller
April 2018
Table 7. Failure Rates for Fisher 249 Displacer Sensors with DLC3100 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
SFF

Application Limits

D Safety Instrumented Function design verification must be done for the entire collection of equipment used in the
Safety Instrumented Function including the DLC3100 SIS digital level controller. The SIS must fulfill the
requirements according to the Safety Integrity Level, especially the limitation of average Probability of Failure on
Demand (PFDavg).
D The DLC3100 SIS digital level controller can only be used for Level or Interface applications.
D The system response time is dependent on the entire final element subsystem. The user must verify the system
response time is less than the process safety time for each final element. The DLC3100 SIS digital level controller
safety function has a fault reaction time upon fault detection of < 1 second plus the mean time to repair.
D Measurement signal used by logic solver must be the analog 4-20 mA signal proportional to the fluid level.
D The logic solver must recognize both high/low alarms. If the logic solver loop uses IS barriers, caution must be
taken to ensure the loop continues to operate properly under the low alarm condition.
D Safe failure in which 4-20 mA current is driven out of range (<3.6 mA or > 21 mA).
D Device Response Time: less than 1 second
D When using the DLC3100 SIS in redundant applications, the owner-operator of the facility should institute
common causes training and more detailed maintenance procedures specifically oriented toward common
cause defense.

Environmental Limits

D Operating ambient temperature: -40_C to 80_C (-40_F to 176_F)
D Humidity: tested per IEC61298-3 Section 6
D Electromagnetic Compatibility: tested per IEC61326-3-2
D Vibration: tested per ISA 75.13 and FTEP 3B1
8
SU
DD
DU
Instruction Manual Supplement
High Trip
Failure Rate (FIT) Failure Rate (FIT)
38
10
570
342
77
151
61
205
34
91.0%
D104215X012
Low Trip
39
8
568
340
77
151
63
205
34
90.7%