Masoneilan SVI II AP Installation and Maintenance ... - GE Energy

Advanced Usage
E
Technology to Maximize Savings and Process Performance
This section shows examples of techniques for achieving superior process results by using
ValVue with SVI II AP to simplify maintenance and to achieve the benefits of SVI II AP’s
advanced diagnostics capabilities. It is assumed that you are using HART communications
with a modem and ValVue. Refer to the ValVue Instruction Manual for complete instructions
on these and other procedures.
Tight Shutoff Application to Protect from Seat Erosion
The Tight shutoff feature can be programmed to prevent valve seat erosion using the full
actuator force to eliminate damaging leakage. At a position setpoint of 2%, for example, this
function allows full thrust to occur when the input signal is less than 2%. This solves a
common cause of valve repair. Do not use tight shutoff if it is necessary to throttle the valve
at very small flows.
Tight Shutoff Application to High Pressure Liquid Letdown Valve Trim
When staged trim is used in High Pressure Liquid Letdown Valves, Tight Shutoff can be
adjusted to move the valve from the seat to begin throttling at the minimum operable CV
level. Using the tight shut-off feature in SVI II AP prevents valve seat damage that can occur
when throttling at clearance flows. See recommended Tight Shutoff settings in the following
table. Tight shutoff can be adjusted with pushbuttons or with ValVue or a HART
communicator.
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