isher Cavitrol III One-, Two-, and Three-Stage Trims0 pages

Product Bulletin

Cavitrol III Trims

80.2:030
March 2012

D100196X012

Fisherr Cavitrol™ III One-, Two-, and
Three-Stage Trims
Cavitrol III trims (figures 1, 2, and 3) are used for
cavitating liquid applications in various globe and
angle valve bodies (see tables 1, 2, and 3). (Contact
your Emerson Process Management sales office for
angle valve information.) One-stage trims are normally
used where the pressure drop is below 99 bar (1440
psi); two- and three-stage trims are normally used
where the pressure drop is between 99 and 207 bar
(1440 and 3000 psi). The Cavitrol III trims are
frequently used in pump recirculation and startup
systems in the power, process, oil production,
chemical refining, and other industries.

W3708-1

CAVITROL III ONE-STAGE TRIM PARTS

Unless otherwise noted, all NACE references are to
NACE MR0175-2002.

Features

Controls or Helps to Eliminate Cavitation
Damage–Cavitrol III trim can lengthen valve service
life and reduce maintenance downtime. The shape
and spacing of holes in the cage wall circumference
helps prevent cavitation in a properly sized valve,
effectively controlling or helping to eliminate
(depending upon service conditions) cavitation
damage and resulting valve failure.

Rangeability–Many special characterizations are
available in Cavitrol III cages to match rangeability
requirements of specific systems.

Resistance to Erosion Damage–Standard hardened
trim materials provide excellent wear resistance,
resulting in long trim life. The contoured valve plug
seat reduces fluid separation, helps direct fluid away
from trim, and helps protect against erosion
damage.

Versatility–Available in NPS 1 to 24 globe or angle
valves with weld-end or flanged-end connections.

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W3559

CAVITROL III TWO- OR THREE-STAGE TRIM PARTS

Easy Maintenance–Cage-type trim allows removal
and inspection of parts without taking the valve
body out of the pipeline. Fine particles very seldom
cause the accumulation problem associated with
labyrinth-type trim.

Efficient Operation–A low inlet pressure to the final
stage is maintained by the flow-down configuration
and the successively larger flow area of each stage.
At the third stage inlet (see figure 6), about 85% of
the total pressure drop has already occurred and the
vena contracta pressure remains above the liquid
vapor pressure. This helps to prevent cavitation in a
properly-sized valve.

Trim Interchangeability–Cavitrol III one-stage trim
is interchangeable with standard trims. Quick trim
changes can be made with no additional parts, such
as spacers, longer bolts, and special gaskets for
valve sizes greater than NPS 1.