Brochure
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Nonstop High-Cycle Applications | 7
Validated Through Testing
The Emerson PSA testing facility was designed to represent
the PSA process as accurately as possible. A large volume tank
(see ) provides process pressure in high capacity to all of the
control valve assemblies currently being tested. Instrument air
is filtered and dried using desiccant, and is then regulated to
the appropriate pressure for each control valve assembly.
Each control valve assembly being tested is comprised of
standard option parts, including valve seats, packing, actuator
springs, and diaphragms. Each control valve assembly is
controlled with a Fisher FIELDVUE digital valve controller.
During the course of testing, no parts are changed—all data is
gathered with the original seats, springs, and diaphragms as
received from the factory.
Using Emerson’s DeltaV
™
workstation (see ) and switching
solenoids, in conjunction with the Fisher FIELDVUE digital
valve controller, the test valve is subjected to full bi-directional
pressure swings. This combination allows cycles (see ) to
accumulate very quickly—up to 25,000 cycles per week—while
being faithful to the process conditions.
Improve Reliability
The valve plug is pressurized to 350 psi then stroked from
0–100–0% travel, subjecting the valve to a 350 psi pressure
drop as the air vents to atmosphere. Actuator stroke time is
controlled so that the 0–100% and 100–0% strokes occur in
under two seconds. In addition to counting cycles, pressure
taps have been installed allowing for seat leak testing as cycles
accumulate.
Each control valve assembly is inspected several times per
week for general operation. This checklist includes things like
smooth operation, evidence of wear, and any audible changes.
The use of Fisher FIELDVUE digital valve controllers allows
for monitoring of diagnostic and performance data such as
friction, spring rate, and bench set. This information gives a
detailed picture of what is happening inside the valve as cycle
counts reach and exceed 1,000,000.