Designing An Sif Using An Svi Ii Esd; Svi Ii Esd Device Description; Safety Function - Baker Hughes Masoneilan SVI II ESD Quick Start Manual

SVI II ESD Device Description

An ESD valve is a valve that is operated to ensure that the process is brought to its safe state.
During normal operation, these ESD valves are typically energized to stay open. In case of an un-
safe situation, the ESD valve is de-energized by the Safety System. The SVI II ESD device performs
this shutdown function for Safety Instrumented Functions (SIF) that require field devices to be
certified for safety related applications according to IEC61508 and is certified by TUV for use up
to SIL3 with a HFT of 0 in low demand applications. It is important to note that the built-in micro-
processor is used for valve diagnostics only. The microprocessor has no direct role in performing
the designated safety function therefore the SVI II ESD is considered a Type A device.
The SVI II ESD is a valve controller that mounts on a pneumatically actuated valve assembly. Its
role is to position an emergency shutdown valve to 0% or 100% with a PFDavg in accordance
with IEC61508 for SIL3 application.
Because of its capability of monitoring data from its embedded sensors, the SVI II ESD is capable
of validating the health of its integral components. Also, with the ability of partially stroking the
ESD valve while in normal operations (energized to stay open); it becomes possible to validate
the health of the valve and actuator assembly. Periodic testing of the ESD valve reduces the PF-
Davg by detecting dangerous failures.

Designing an SIF Using an SVI II ESD

The following must be taken into consideration when designing a SIF (Safety Instrumented Func-
tion) using the SVI II ESD:

Safety Function

When de-energized, the SVI II ESD moves to its fail-safe position. For a single-acting PST control-
ler the safe state is when the port Actuator 1 is exhausted to a pressure that is less than 1 PSIG
(0.069 bar, 6.9 kPa). The valve actuation means must be of a type that automatically moves the
valve to the safe state when the digital valve controller is in its safe state.
The SVI II ESD is intended to be part of final element subsystem as defined per IEC 61508 and the
achieved SIL level of the designed function must be verified by the designer.
14 | =BHGE
"Safety Function" on page 14
"Environmental Limits" on page 15
"Design Verification" on page 15
"SIL Capability" on page 15
"Connecting the SVI II ESD to the SIS Logic Solver" on page 16
"General Requirements" on page 17
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