Dresser Masoneilan SVI II AP, Инструкция по эксплуатации

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SVI II AP Instruction Manual
136
DRAFT 6/
8/10
Dresser Masoneilan
Using ValVue Diagnostics
SVI II AP advanced features are simple to use with ValVue software. The following
examples illustrate some uses.
Continuous Diagnostics
SVI II AP continuously gathers critical information that can be used to predict
maintenance intervals for control valves. These are:
q
Total Travel
q
Number of cycles
q
Time open
q
Time closed
q
Time near closed
Monitoring a Valve Bellows Seal
The SVI II AP automatically stores the accumulated valve stroke reversals, as Number of
cycles. ValVue can be used to periodically retrieve the values and to track the remaining
life of a bellows seal or packing. Total travel can also be used to estimate the remaining
life of packings and seals.
Critical Service, Cavitation Control Trim
The time near closed, of a valve with severe service when near the seat, can be
monitored by ValVue and saved to permanent files to monitor and predict maintenance
needs. You can use ValVue to specify the criterion for time-spent-near-closed (a valve
position such as 4%, for example). See also Tight shutoff- Application to High Pressure
Liquid Letdown Valve Trim.
Table 25 Tight Shutoff Parameters for HIgh Pressure Liquid Letdown Trim
Masoneilan Valve
Type
Valve Trim Type Set Tight Shutoff Positioner
Characteristics
Lincoln Log Any 15% Linear
41000 VRT Type S Partial Stack 6% Linear
41000 VRT Type S Full Stack 3.5% Linear
41000 VRT Type C Cage 6% Linear
28000 Varilog 5% Linear
Any Class V Shutoff 2% Linear