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Safety Manual
00809-0200-5100, Rev GB
Installation and Configuration
February 2017
Installation and Configuration
4.2.4 Setting the SIL High Alarm Limit
The desired SIL High Alarm Limit needs to be adjusted for the expected product level rate.
“Margin to add” in Ta bl e 4 -8 is a safety margin to add to the desired SIL High Alarm Limit. This
ensures that the reaction time of the 5900 for different level rates is taken into account when
specifying the desired SIL High Alarm Limit.
Table 4-8. Margin to add to the desired SIL High Alarm Limit for various level rates
The “Minimum value for SIL High Alarm Limit” specifies how close to the SIL Reference Point that
the High Alarm Limit may be set. Different figures apply depending on the level rate that may
occur in the tank, see Tabl e 4- 9.
Table 4-9. Minimum value for SIL High Alarm Limit
SIL Holdoff Distance Adjustment should be added to the figures in Ta bl e 4 -9 , see Figure
4-7 on page 20
If a LPG/LNG verification pin is installed in the Still-pipe, it must be placed > 500 mm
above the SIL High Alarm Limit
See an example of how to configure the SIL High Alarm Limit in “Example” on page 28.
Margin to add (mm)
Level Rate
< 2 mm/s < 20 mm/s < 50 mm/s
120 380 980
Antenna Minimum value for SIL High Alarm Limit (mm)
Level Rate
< 2 mm/s < 20 mm/s < 50 mm/s
Horn 625 880 1480
Parabolic 625 680 1280
Array 5 inch 1125 1380 1980
Array 6 inch 1125 1380 1980
Array 8 inch 1425 1680 2280
Array 10 inch 1225 1480 2080
Array 12 inch 1525 1780 2380
LPG/LNG 725 980 1580
Cone 4 inch 425 680 1280
Cone 6 inch 525 780 1380
Cone 8 inch 625 880 1480
Cone Pipe 1” and 2” 225 460 1080
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