34
Reference Manual
00809-0100-4530, Rev DD
May 2016
3.2.11
Installation and configuration considerations for ESD
systems
shows a common example of an Emergency Shutdown (ESD) system in a
separator. High-high and low-low transmitters act as redundant safeguards. They will
trigger emergency shutdowns or redirect flow of the application. In addition, there are one
or several process control units that continuously measure and report the actual level in the
tank to the host system and operators.
The high-high unit will always be empty during normal operation, and will indicate empty in
the host system. The low-low unit will always be full during normal operation, and will
indicate full in the host system as well.
Figure 3-18. ESD System in a Separator
High-high unit
The alarm levels must be located near the bottom inlet with considerable margin to the
Blind Zones to ensure robust and accurate readings. See
for
further information.
Figure 3-19. High-High Unit
High-high unit
Low-low unit
20 mA
4 mA
Warning
Shutdown
