October 1999 Bulletin 51.

2:CAV4

Design CAV4 Control Valve

The Design CAV4 control valve (figure 1) with Features
Cavitrol! IV trim is designed specifically for liquid ap-
plications, such as boiler feedwater recirculation, where # Cavitation Eliminated—A properly sized Design
pressure drops are above 207 bar (3000 psi) and cavi- CAV4 valve with Cavitrol IV trim will eliminate cavita-
tation is a serious problem. The Design CAV4 valve is tion and its resultant damage and noise.
available in a broad range of valve body sizes and
styles, including 2- through 6-inch angle, globe, and # Longer Trim Life—Patented pressure-staging
offset globe. design and separation of shutoff and throttling loca-
tions prevent clearance-flow erosion. Hardened trim
The Design CAV4 valve’s various valve plug construc- materials result in excellent wear resistance.
tions (figure 2) provide temperature capabilities
through 417"C (800"F). The seal ring construction is # Tight Shutoff—Soft metal-to-metal seat provides
used where temperatures are equal to or lower than tight shutoff without the need for periodic lapping. The
232"C (600"F) (see figure 6), and both the stem-bal- anti-extrusion ring provides an enhanced valve plug
anced and the piston ring constructions are used with seal.
temperatures up to 417"C (800"F). In addition, the
Design CAV4 valve is offered with either a separable # TSO (Tight Shutoff) Trim—Valves with TSO trim
seat ring for low-temperature (up to 232"C [450"F]) (figure 2) are factory tested to a more stringent Fisher
applications or with an integral seat cage for high-tem- Controls test requirement of no leakage at time of
perature (up to 417"C [800"F]) applications. The shipment using ANSI/FCI Class V procedures.
3-inch size is available only with a clamped-in lower
cage and replaceable seat ring. (continued on page 3)

TYPE 657
ACTUATOR

SEPARABLE
SEAT RING
CAGE
RETAINER
DESIGN CAV4 LOWER CAGE
VALVE BODY ASSEMBLY

UPPER
CAGE

W3667-1 / IL W5601 / IL
W2700-1 / IL VALVE PLUG AND
STEM ASSEMBLY
ANGLE OFFSET GLOBE

Figure 1. Type 657-CAV4 Control Valve Assembly with Cavitrol IV Trim

D101497X012
Bulletin 51.2:CAV4
Specifications
Available Configurations and Valve Body Sizes Flow Direction
Common Characteristics: Design CAV4 angle, In through the side connection and out the bottom
globe, or offset globe valve with four-stage Cavitrol connection
IV trim including soft metal-to-metal seat. Valve plug
action is push-down-to-close Noise Levels
Seal Ring Construction: $ 2, $ 3, $ 4, or $ 6 in.
valve body with pressure-balanced valve plug and Because of cavitation elimination, noise is not a
spring-loaded PTFE seal ring. For use in low-tem- problem with Cavitrol IV trim. For virtually all ap-
perature applications plications, noise levels will be below 90 dBA. If more
Stem-Balanced Construction: $ 2 or $ 4 in. stringent noise specifications must be met, contact
valve body with stem-balanced valve plug (valve your Fisher Controls sales office or sales represen-
stem diameter—for that portion of stem that passes tative
through bonnet—is equal to nominal port diameter).
For use in high-temperature applications Construction Materials
Piston Ring Construction: 6 in. valve body with
See table 1
pressure-balanced valve plug and five graphite pis-
ton rings. For use in high-temperature applications
Flow Characteristic
End Connection Style(1) Linear
Buttwelding Ends: All buttwelding end schedules
per ASME B16.25 that are compatible with ASME Maximum Flow Coefficients (CV)
B16.34 valve body rating
Linear: $ 2 in. valve, 8.25; $ 3 in. valve, 14.6; $ 4
Raised-Face or Ring-Type Joint Flanged Ends:
in. valve, 21.9: $ 6 in. valve, 55.6
Inlet connection is ANSI Class 2500 flange per
Characterized:$ 2 in. valve, 11.3; $ 3 in. valve,
B16.5. Outlet connection mates with ANSI Class
24; $ 4 in. valve, 38.2; $ 6 in. valve, 89.1; also see
2500 flange and has tapped bolt holes with line
Fisher Controls Catalog 12
flange studs

Maximum Inlet Pressure and Temperatures(1)(2) Valve Recovery and Cavitation Coefficients
Consistent with applicable Class 2500 pressure Recovery Coefficient
temperature ratings per ASME B16.34 unless limit- Linear: Km = 0.99. Characterized: Km = 0.98. This
ed by individual pressure drop limits shown in figure value defines the maximum allowable pressure drop
6 or temperature limits in table 1 that is effective in producing flow as shown in the
following equation:
Maximum Pressure Drop(2)
!Pallowable = Km (P1 (flowing) --rcPv)
See figure 6
Cavitation Coefficient
Material Temperature Capabilities(2) Linear and Characterized: Kc = 1.0. This value
Seal Ring Construction: 18 to 232"C (0 to 450"F) predicts the beginning of cavitation-related damage
Stem-Balanced and Piston Ring Constructions: as shown in the following equation:
Up to 427"C (800"F) unless limited by selection of !PCavitation = Kc (P1 (flowing)Pv)
other parts (table 1)
where,
Shutoff Classification !Pallowable = maximum allowable pressure drop that
TSO (Tight Shutoff) Trim: Valves with TSO trim is effective in producing flow, bar (psi)
are factory tested to a more stringent Fisher P1 (flowing) = flowing inlet pressure, bar, absolute
Controls test requirement of no leakage at time of (psia)
shipment using ANSI/ISA Class V procedures.
rc = critical pressure ratio from Catalog 12
Piston Ring Construction: Class IV per
ANSI/FCI 70-2 Pv = vapor pressure of liquid at inlet temperature,
All Others: Class VI per ANSI/FCI 70-2 bar, absolute (psia)
- Continued -

2
 Bulletin 51.2:CAV4
Specifications (Continued)
Port Diameters and Unbalance Area Yoke Boss and Valve Stem Diameters

See table 2 See table 2

Approximate Weight
Minimum Seat Load Force See table 2
First refer to figure 7 to determine minimum seat
load per inch of port circumference; then multiply Options
that value by the port circumference from table 2 $ Flushing trim, two plates used in place of Cavitrol
IV trim, to protect valve body surfaces and Cavitrol
IV trim from damage during pipeline flushing:
Valve Plug Travel $ characterized cage; and $ driver for installation
and removal of cage retainer $ ENVIRO-SEAL!
See table 2 packing is available
1. DIN (or other) ratings and end connections can usually be supplied: contact your Fisher Controls sales office or sales representative.
2. The pressure/temperature limits in this bulletin and any applicable linear limitation should not be exceeded.

Table 1. Construction Materials and Temperature Capabilities

TEMPERATURE
PART MATERIALS CAPABILITIES
"C "F
Standard WCB carbon steel casting
Valve Body and Bonnet See figure 6 See figure 6
Optional C5 or WC9 alloy steel casting
Valve Plug S44004 (440C stainless steel heat-treated) --29 to 427 --20 to 800
3/4 inch stem in 4 inch body, S31600/S17400 (316/17-4PH) stainless steel --101 to 427 --150 to 800
Valve Stem
All other stems, 316 stainless steel --254 to 427 --425 to 800
Seat Ring 17-4/316 SST stainless steel --29 to 232 --20 to 450
Upper Cage, Cage Retainer, and 17-4/316 SST stainless steel (cages)
--29 to 427 --20 to 800
Lower Cage Assembly and H1075 electrolized (retainer)
Valve Plug Seal Ring(1) Spring-loaded PTFE seal --18 to 232 0 to 450
Valve Plug Backup Ring(1) S41600 (416 stainless steel) --29 to 427 --20 to 800
Seal Ring Retainer(1) S30200 (302 stainless steel) --254 to 593 --425 to 1100
Piston Ring(2) Graphite (FMS 17F27) --254 to 427 --425 to 800
Bonnet Gasket Silver-plated N04400 (Monel) nickel alloy --254 to 593 --425 to 1100
Cage Gasket 316 stainless steel/graphite --18 to 232 0 to 450
Metal Packing Box Parts 316 stainless steel --254 to 593 --425 to 1100
Body-to-Bonnet Bolting Studs, steel SA193-B7; nuts, steel SA194-2H --29 to 427 --20 to 800
Standard Spring-loaded PTFE V-ring --46 to 232 --50 to 450
Packing PTFE-impregnated composition --73 to 232 --100 to 450
Optional
Laminated graphite/filament --18 to 427 0 to 800
1. For only seal ring construction.
2. For only 6 inch piston ring construction.

Features (continued) # Characterization—Special characterized cages

are available to provide excellent rangeability for spe-
# Efficient Operation—Expanding flow area de- cific system requirements.
sign takes advantage of the ability of the liquid to un-
# Easy Maintenance—Design reduces mainte-
dergo a greater pressure drop in initial stages without
nance downtime by permitting quick disassembly with
cavitating. This results in a much lower inlet pressure
easy access to valve trim and valve plug seat. Separa-
to the final stage.
ble seat ring for low temperature applications (at or
below 232"C [450"F]) makes maintenance easier.

3
Bulletin 51.2:CAV4
Table 2. Additional Valve Body Specifications
VALVE STEM YOKE BOSS PORT PORT UNBALANCE APPROXIMATE
VALVE TRAVEL
DIAMETER DIAMETER DIAMETER CIRCUMFERENCE AREA(1) WEIGHT
SIZE, INCH
mm Inch mm Inch mm Inch mm Inch mm Inch cm2 Inch2 Kg Lb
19.0 3/4 91 3-9/16 167 369
2 38 1-1/2 38.1 1-1/2 119.6 4.71 4.3 0.17
38.1 1-1/2(2) 127 5 182 401
3 19.0 3/4 91 3-9/16 51 2 55.6 2-3/16 174.5 6.87 6.6 0.26 301 664
19.0 3/4 91 3-9/16 532 1172
4 25.4 1 127 5 64 2-1/2 69.9 2-3/4 219.4 8.64 8.1 0.32 532 1172
69.8 2-3/4(2) 178 7 554 1222
6 31.7 1-1/4 127 5 & 5H 102 4 111.1 4-3/8 349.2 13.75 12.9 0.51 1512 3334
1. For seal ring and piston ring constructions. For stem-balanced construction, use port area of 11.4 cm2 (1.77 inch2) for 2-inch valve and 38.3 cm2 (5.94 inch2) for 4-inch valve.
2. Stem-balanced construction has 1-1/4 inch valve stem connection.
3. Stem-balanced construction has 2-inch valve stem connection.

Table 3. Additional Valve Body Specifications for TSO (Tight Shutoff) Trim
MAXIMUM YOKE BOSS PORT DIAMETER PORT CV
VALVE SIZE, TRAVEL SIZE(1) CIRCUMFERENCE REDUCTION
TRIM Nominal Actual TSO
INCH AT 100%
mm Inch mm Inch mm Inch mm Inch mm Inch TRAVEL(2)
91 3-9/16
2 Class 2500 38 1-1/2 38.1 1-1/2 38.1 1-1/2 119.6 4.71 0%
127 5
3 Class 2500 50.8 2 91 3-9/16 55.6 2-3/16 55.6 2-3/16 174.8 6.88 0%
91 3-9/16
4 Class 2500 64 2-1/2 69.9 2-3/4 69.9 2-3/4 219.4 8.64 0%
127 5
1. Consult the factory for larger yoke boss sizes.
2. This column lists the percent reduction of published maximum CV of the trim listed in the TRIM column.

VALVE
PLUG
SEAL
RING

SOFT
METAL-TO-
METAL
SEATING
SURFACES

W3670-1 / IL
STEM-BALANCED W7006-1 / IL

VALVE PLUG CLAMPED-IN LOWER CAGE

THROTTLING FOR 2 & 4 INCH VALVES FOR 3-INCH VALVE
LOCATION
SEPARABLE
SEAT RING
OPTION

CAGE
VALVE PLUG

SEAL RING
CONSTRUCTION
W3668-2 / IL

W7005-1 / IL W3669-1 / IL

TSO (TIGHT SHUTOFF) TRIM PISTON RING

VALVE PLUG FOR 6-INCH VALVE

Figure 2. Sectional View of Design CAV4 Valve Body with Cavitrol IV Trim

4
 Bulletin 51.2:CAV4

NO
SIGNIFICANT
PRESSURE
DROP

MORE THAN
A2148-1 / IL 90% OF THE
PRESSURE
DROP
Figure 3. Standard Cage-Style Anticavitation Trim

Principle of Operation VERY LOW

INLET
PRESSURE
The advantage of the Design CAV4 valve with Cavitrol TO FINAL
IV trim is a result of the following three technological STAGE
advancements not found in any other anticavitation
control valve. W3671-2 / IL

1. All clearance flow subjected to staged pressure drop Figure 4. Cavitrol IV Trim Operation

2. Separation of shutoff and throttling locations

3. An expanding flow area design

The Design CAV4 valve with Cavitrol IV trim solves
Although linear cage-style anticavitation trims can suc- this clearance flow problem by not taking any signifi-
cessfully handle pressure drops to about 207 bar cant pressure drop until the fluid is downstream of the
(3000 psi), they are not effective above 207 bar (3000 seating surfaces (figure 4). As the flow then passes
psi) especially when the valve plug is off the seat and from stage to stage, even the clearance flow is sub-
throttling. As shown in figure 3, the linear cage open- jected to a staged pressure drop. Therefore, unlike the
ings below the valve plug seating surface are open to linear cage-style anticavitation trims, there are no flow-
fluid flow and are staging the pressure drop from P1 to ing conditions where pressure can go directly from P1
P2 as designed. However, the cage openings above to P2.
the valve plug seating surface are nearly blocked by
the valve plug. Even though a small clearance pas-
sage between the cage and the valve plug does exist, In the Cavitrol IV trim design, trim life is lengthened by
the fluid flow rate through this small clearance pas- the separation of the shutoff and throttling locations.
sage is so small that the cage is ineffective in staging Just as all significant pressure drop is taken down-
the pressure drop. Consequently, the clearance flow stream of the shutoff seating surfaces, all significant
pressure drop from P1 to P2 occurs between the valve throttling action occurs as the liquid passes through
plug surface blocking the cage opening and the seat- the four sets of holes downstream of the shutoff seat-
ing surface of the valve plug. The resultant cavitation ing surfaces. As a result, the seating surfaces are not
and erosive flow across the seat damages the valve worn away by throttling control action (unless throttling
plug seating surface. Even with valve plug/cage dia- at very nearly closed for a long time). Also, the throt-
metrical clearances as small as 0.20 mm (0.008 inch), tling areas are not required to have the superior sur-
this clearance flow damage still occurs and becomes face condition otherwise needed by seating surfaces
worse with higher pressure drops. for tight shutoff.

5
Bulletin 51.2:CAV4
the pressure drops were all equivalent to that of the
last stage in Cavitrol IV trim, 11 stages would be re-
quired in the equal-drop trim.

Selection Guidelines
To determine if the Design CAV4 valve with Cavitrol IV
trim should be used, first calculate the application ra-
tio, Ar, and then apply one of the three conditions be-
low:

!!# $%&'"
!" !
!# # " # ("

where,
!PFlow = differential between flowing inlet and
flowing outlet pressure, bar, absolute
(psia)
P1 = inlet pressure, bar, absolute (psia)
Pv = vapor pressure of process liquid at
inlet temperature, bar, absolute (psia)

A2149-1 / IL
1. If the application ratio is less than 1.0 and the maxi-
mum pressure drop is greater than 206 bar (3000 psi),
service is potentially cavitating and a Design CAV4
Figure 5. Staged Pressure Drop Patterns valve with Cavitrol IV trim should be selected.

2. If the application ratio is equal to or greater than 1.0

and the maximum pressure drop is less than or equal
In conventional staged-trim designs, cavitation usually to 206 bar (3000 psi), service is flashing and the De-
does not exist until the final stage. Figure 5 illustrates sign CAV4 body with Cavitrol IV trim should be se-
why this happens. As shown, the greater the pressure lected.
drop through the final stage, the lower the vena con-
tracta pressure (Pvc). If Pvc is less than or equal to Pv, 3. If the application ratio is less than 1.0 and the maxi-
and P2 is greater than Pv, then cavitation will result. mum pressure drop is less than 206 bar (3000 psi),
then refer to other anticavitation products.

The Design CAV4 valve avoids this problem by means Refer to table 1 and figure 6 for trim material selection.
of its unique expanding flow area design. Each of the
four Cavitrol IV trim stages has a successively larger
flow area. The result is very efficient operation be-
cause more than 90 percent of the overall pressure
drop is taken in the first three stages where there is
little danger of bubble formation. Consequently, a rela- Installation
tively low inlet pressure to the final stage is achieved.
Figure 5 also compares the pressure drop pattern The Design CAV4 valve with Cavitrol IV trim must be
through the four stages in the expanding area Cavitrol installed with the actuator mounted vertically above the
IV design with a pattern representing a six-stage trim valve body. Nonvertical positions may cause uneven
design with each stage taking an equal portion of the trim wear and, thus, decrease trim life. Flow through
total pressure drop. As can be seen, the inlet pressure the valve body must be in the direction indicated by
to the last stage of Cavitrol IV trim is always less than the flow arrow on the valve. For long service life and
the inlet pressure to the sixth stage of an equal-drop effective operation, the flowing media should be clean.
cage. Therefore the Pvc of the Cavitrol IV cage re-
mains higher than the Pvc of an equal-drop cage. If Dimensions are shown in figure 8.

6
 Bulletin 51.2:CAV4

6000

PRESSURE, (psig)
5000

4000

3000

OXIDIZING
2000 SERVICE NON-
OXIDIZING
SERVICE

450 500 600

TEMPERATURE, "F

EXTENDED PRESSURE/TEMPERATURE UNITS

FOR SEAL RING CONSTRUCTION WITH
PEEK ANTI-EXTRUSION RINGS

B1605 / IL

Figure 6. Pressure Drop/Temperature Capabilities

7
Bulletin 51.2:CAV4
5. Range of flowing inlet pressures

6. Maximum outlet pressure

7. Pressure drops

a. Range of flowing pressure drops

b. Maximum at shutoff

8. Flow rates

a. Minimum controlled flow

b. Normal flow

c. Maximum flow

A2922-1 / IL
9. Required Cv

10. Line size and schedule

Figure 7. Recommended Seat Load Force for All Constructions
11. Angle, globe or offset globe valve body

Valve Information
Ordering Information To determine what information is needed for ordering
When ordering, specify: the valve and trim, refer to the specifications on
page 2. Review the description at the right of each
specification or in the referenced tables, figures, and
Application Information bulletins, and indicate the desired choice wherever
there is a selection to be made.
1. Process liquid—State particle size and type of en-
trained impurities, if any
Actuator and Accessory Information
2. Specific gravity of liquid
Select the specific actuator and accessories from the
3. Temperature and vapor pressure of liquid appropriate bulletins. Piston or diaphragm actuators
may be used. Specify any additional ordering informa-
4. Critical pressure tion as required from actuator or accessory bulletins.

8
 Bulletin 51.2:CAV4

D
VALVE END A G YOKE BOSS DIAMETER, mm (INCH) M
SIZE, CONNECTION
90 (3-9/16) 127 (5) 127 (5H) 178 (7)
INCH STYLE(1)
mm Inch mm Inch mm Inch mm Inch mm Inch mm Inch mm Inch
BWE 249 9.81 406 16.00 324 12.75 360 14.19 --- --- --- --- --- ---
2 RF 249 9.81 406 16.00 324 12.75 360 14.19 --- --- --- --- 95.3 3.75
RTJ 251 9.87 408 16.06 324 12.75 360 14.19 --- --- --- --- 93.7 3.69
3 BWE 256 10.06 552 21.75 324 12.75 --- --- --- --- --- --- --- ---
BWE 344 13.56 618 24.31 430 16.94 454 17.88 --- --- 454 17.88 --- ---
4 RF 344 13.56 618 24.31 430 16.94 454 17.88 --- --- 454 17.88 133.4 5.25
RTJ 349 13.75 622 24.50 430 16.94 454 17.88 --- --- 454 17.88 128.5 5.06
BWE 457 18.00 1038 40.88 --- --- 432 17.00 432 17.00 --- --- --- ---
6 RF 457 18.00 1038 40.88 --- --- 432 17.00 432 17.00 --- --- 177.8 7.00
RTJ 464 18.25 1045 41.13 --- --- 432 17.00 432 17.00 --- --- 184.2 7.25
1. BWE—buttweld end; RF—raised flange; RTJ—ring type joint.

25.4 25.4 25.4

(1.00) (1.00) (1.00)

NOTE:
FOR DIMENSIONS OF VALVES WITH DIN (OR OTHER) END CONNECTIONS.
CONSULT YOUR FISHER CONTROLS SALES OFFICE OR
SALES REPRESENTATIVE.

mm
B1607-1 / IL (INCH)

Figure 8. Dimensions

9
Bulletin 51.2:CAV4

Cavitrol, ENVIRO-SEAL, Fisher, Fisher-Rosemount, and Managing The Process Better are marks owned by Fisher Controls International, Inc. or Fisher-Rosemount Systems, Inc.
All other marks are the property of their respective owners.
This product may be covered by one or more of the following patents: 5,129,625; 5,131,666; 5,056,757; 5,230,498; and 5,299,812 or under pending patents.
%Fisher Controls International, Inc. 1982, 1999; All Rights Reserved
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be construed as warranties or guarantees, express
or implied, regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specifications of such products at any time without notice.

For information, contact Fisher Controls:

Marshalltown, Iowa 50158 USA
Cernay 68700 France
Sao Paulo 05424 Brazil
Singapore 128461

10
Printed in U.S.A.