16
Sizing & Selection
Linear Actuator Sizing,
Unbalanced Trim
Introduction
An important part of selecting the correct control valve
is the proper sizing of its actuator. In throttling services,
three questions must be answered:
1. Will the actuator handle the throttling differential
pressure?
2. Will the actuator provide sufficient thrust to overcome
application pressures to open or close the valve,
and generate enough seat loading for tight shutoff?
Table 16-I: Guardian Metal Bellows
Effective Area
Model
Number
Body Size
(inches)
Bellows
Effective
psi Rating Bellows Area
1-LP
1
⁄2 , 3 ⁄4 , 1
160
.886
1-HP
1
3
310
.886
1
1 ⁄2 , 2
160
1.916
1
310
1.916
2-LP
2-HP
⁄2 , ⁄4 , 1
1 ⁄2 , 2
3. Will the spring fail the valve in the proper direction?
3-LP
3
160
2.835
With on/off services, only questions 2 and 3 must be
answered.
3-HP
3
310
2.835
4-LP
4
160
3.343
The equations in this section use the following variables:
AL = Lower cylinder area, in2
AU = Upper cylinder area, in2
AS = Area of the seat, in2 (see Table 16-IV or
equation 16.1)
AStem* = Plug stem cross-sectional area, in2 (see
Table 16-IV or equation 16.3)
AR = Area of the seat retainer bore, in2 (see
equation 16.2)
P1 = Pressure on upstream side of the valve,
psig
P2 = Pressure on downstream side of the valve,
psig
PS = Air supply pressure, psig
SE = Spring force with the spring extended to full
stroke, lbs (see Table 16-VI)
SR = Spring force with the spring fully retracted,
lbs (see Table 16-VI)
SFC30 = Spring force at 30 percent of stroke in failclosed actuators, lbs (see Table 16-VI or
equation 16.4)
SFO30 = Spring force at 30 percent of stroke in failopen actuators, lbs (see Table 16-VI or
equation 16.5)
FP = Packing friction, lbs (see Table 16-V)
RSL = Required seat load to achieve desired
shutoff, lbs (see equation 16.6)
4-HP
4
310
3.343
Rev. 4/94
* Use effective bellows area for Guardian valves, see Table 16-I.
For Guardian II valves, see page 16-15.
When an actuator’s stroke length exceeds the longest
stroke length shown for that size actuator on Table 16VI, the actuator will not have a spring. For actuators
without a spring, SE= SR= 0.
The areas of the seat, AS, and the seat retainer bore, AR,
are calculated using the following equations. Note that
the area of the seat retainer bore is not used when sizing
actuators for valves with standard trim or when sizing
actuators for Class 150 through 600 MegaStream valves.
AS =
AR =
πdS2
(16.1)
4
π(dS+0.125)2
4
(16.2)
Where:
dS = The seat orifice diameter, inches (Trim Number)
The plug stem cross-sectional area, Astem, is calculated
using the following equation:
Astem =
πdstem2
4
(16.3)
16-1
Where:
dstem =The plug stem diameter, inches (see Table 16IV)
The spring forces at 30 percent of stroke in fail-closed
and fail-open actuators, SFC30 and SFO30, are calculated
using the following formulas:
SFC30 = SE + RS (0.30) S
(16.4)
SFO30 = SR - RS (0.30) S
(16.5)
Where:
RS = Spring rate, lb/in (from Table 16-VI)
S = Stroke length, inches
The required seat load, RSL, is calculated using the
following equation:
RSL = πdCLS
(16.6)
Where:
LS = Seat load per circumferential inch to
achieve
desired shutoff, lbs/in (from Table 8-II)
dC = The diameter of the seating contact surface,
in (from the following table)
Trim Type
dC=
Standard
MegaStream
Tiger-Tooth
Trim Number
CavControl
ChannelStream
Trim Number +
0.125 inch
Step 1: Determine Actuator’s Maximum
Allowable Throttling Pressure Drop
(Not required for on/off service)
Refer to Table 16-IV to find the standard actuator for the
given body size.
Determine the maximum allowable throttling pressure
drop (∆Pa) that the selected actuator can handle by
using equations (16.7) and (16.8):
Air-to-open, flow-over: or air-to-close, flow-over:
ACJO
∆Pa = ≈≈≈≈≈
AS
(16.7)
Air-to-close, flow-under; or air-to-open, flow-under:
ACJC
∆Pa = ≈≈≈≈≈
AS
16-2
(16.8)
Where:
∆Pa = Maximum allowable throttling pressure drop,
psi
AC = Area of cylinder actuator, square inches (see
Table 16-III; for air-to-open flow, use the
lower cylinder area; for air-to-close flow, use
upper cylinder area)
AS = Area of the seat, square inches
JO = Air supply adjustment factor for flow-over (see
Table 16-II)
JC = Air supply adjustment factor for flow-under
(see Table 16-II)
Table 16-II:
Air Supply Stiffness Factors
Supply Pressure
JC
JO
30
45
60
80
100
150
14.1
28.2
37.6
56.4
75.2
118.0
14.1
20.7
28.2
35.8
42.4
61.2
Compare the maximum allowable throttling pressure
drop to the actual pressure drop. If the actual throttling
drop is less than ∆Pa, the selected actuator is sufficient.
However, if the actual throttling drop is greater than
∆Pa, the next larger actuator size should be chosen and
the above calculation should be repeated.
The maximum allowable throttling pressure drop may
also be selected by referring to the appendix at the end
of this section. To use these tables, follow the procedure below:
A) Select the correct table based on the trim size
used on the valve.
B) Find the correct air supply pressure in the left
column.
C) Looking to the right, find the allowable throttling
drop (∆Pa) for the various actuator sizes and air
actions (air-to-open or air-to-close).
Table 16-III: Actuator Data
Cylinder
Size
Cylinder
Bore Dia.(in.)
Upper Cylinder
Area (sq. in.)
Lower Cylinder
Area (sq. in.)
Stem Dia.
(in.)
Stem Area
(sq. in.)
Max. Vol. Over
Piston (cu.in.)
25
5.50
23.76
22.97
1.00
0.79
100
50+
7.75
47.17
46.39
1.00
0.79
331
50
7.75
47.17
45.67
1.38
1.50
331
100+
11.00
95.03
93.26
1.50
1.77
1031
100
11.00
95.03
91.06
2.25
3.98
1031
200
15.50
188.7
184.7
2.25
3.98
2087
300
19.50
298.6
292.7
2.75
5.94
3733
400*
15.50
371.5
365.5
2.75
5.94
3033
500
25.25
500.7
494.8
2.75
5.94
5519
600*
19.50
590.2
583.1
3.00
7.07
5661
* Tandem, double piston configuration
+ Used as oversized actuators in place of the next smaller actuator
Table 16-IV: Standard Unbalanced Valve/Actuator Data
Valve Size
(inches)
Rating
Class
Full Area
Trim Size
Seat Area
(sq. in.)
Stem
Dia.
Stem Area
(sq. in.)
Std. Act.
Size*
Stroke
(inches)
1
/2
150-600
.50
.196
.562
.248
25
.75
3
/4
150-2500
.72
.405
.562
.248
25
.75
1
1
1
150-600
900-1500
2500
.81
.81
.72
.518
.518
.405
.562
.562
.562
.248
.248
.248
25
25
25
.75
.75
.75
11/2
11/2
11/2
150-600
900-1500
2500
1.25
1.25
1.00
1.23
1.23
.785
.875
.875
.875
.601
.601
.601
25
50
50
1.00
1.00
.75
2
2
2
150-600
900-1500
2500
1.62
1.62
1.25
2.07
2.07
1.23
.875
.875
.875
.601
.601
.601
25
50
50
1.50
1.50
1.00
3
3
3
150-600
900-1500
2500
2.62
2.62
2.00
5.41
5.41
3.14
1.125
1.5
1.125
.99
1.77
.99
50
100
100
2.00
2.00
1.50
4
4
4
150-600
900-1500
2500
3.50
3.50
2.62
9.62
9.62
5.41
1.125
1.5
1.5
.99
1.77
1.77
50
100
100
2.50
2.50
2.00
6
6
6
150
300-1500
2500
5.00
5.00
4.00
19.63
19.63
12.57
1.125
2.0
2.0
.99
3.14
3.14
50
100
100
3.00
3.00
3.00
8
8
8
8
150
300-600
900-1500
2500
6.25
6.25
6.25
5.00
30.68
30.68
30.68
19.63
1.5
2.0
2.5
2.5
1.77
3.14
4.91
4.91
100
100
100
100
4.00
4.00
4.00
3.00
10
10
10
10
150
300-600
900-1500
2500
8.75
8.75
8.00
6.25
60.13
60.13
50.27
30.68
2.0
2.5
3.0
3.0
3.14
4.91
7.07
7.07
100
100
100
100
4.00
4.00
4.00
4.00
12
12
12
150
300-600
900-2500
9.50
9.50
8.00
70.88
70.88
50.27
2.0
3.0
3.0
3.14
7.07
7.07
100
100
100
4.00
4.00
4.00
14
14
150
300-600
11.00
11.00
95.03
95.03
3.0
3.0
7.07
7.07
100
100
4.00
4.00
* Minimum standard actuator size. Oversized actuators may be required for large pressure drops.
16-3
TABLE 16-V: Typical Stem Packing Friction Forces
Note: All numbers in pounds-force
Plug Stem
Diameter*
(inches)
Teflon
Single V
Teflon
Twin V
Glass and
Carbon-filled
Teflon
0.56
0.88
1.13
1.50
2.00
2.50
3.00
44
49
54
64
82
105
133
49
54
50
60
75
90
105
45
63
78
103
141
184
232
Standard Twin
Grafoil
Grafoil
356
560
712
954
1272
1590
1908
642
842
1001
1239
1557
1875
2193
Braided
PTFE
Braided
AFPI
SafeGuard
SureGuard
Single V
SafeGuard
SureGuard
Twin V
44
49
54
64
82
105
133
271
344
399
486
600
714
829
52
70
85
111
149
192
239
68
89
106
135
177
225
279
TABLE 16-VI: Cylinder Actuator Spring Data
Air-to-open (Air-to-retract)
Cylinder
25
50
100
thru
600
16-4
Stroke
(inches)
Spring
Design
Rate
(lb/in)
SE: Spring
Extended
(lbs)
3
⁄4
1
1 1⁄2
STD
STD
STD
180
180
180
281
236
146
3
⁄4
1
1 1⁄2
1 1⁄2
2
2 1⁄2
3
1 1⁄2
2
2 1⁄2
3
DUAL
DUAL
DUAL
STD
STD
STD
STD
DUAL
DUAL
DUAL
DUAL
447
447
447
164
164
164
164
447
447
447
447
2
2 1⁄2
3
4
2
2 1⁄2
3
4
2
21⁄2
3
4
STD
STD
STD
STD
HEAVY
HEAVY
HEAVY
HEAVY
DUAL
DUAL
DUAL
DUAL
300
300
300
300
535
535
535
535
885
885
885
885
SFC30
(lbs)
Air-to-close (Air-to-extend)
SR: Spring
Retracted
(lbs)
SR: Spring
Retracted
(lbs)
SFO30
(lbs)
SE: Spring
Extended
(lbs)
322
290
227
416
416
416
450
450
450
410
396
369
315
270
180
629
629
405
369
287
205
123
1194
970
747
523
728
762
606
443
385
328
271
1395
1238
1082
925
964
1075
1075
615
615
615
615
1864
1864
1864
1864
656
656
656
656
582
558
533
508
410
328
246
164
1125
975
825
525
2098
1831
1563
1028
3471
3029
2586
1701
1305
1200
1095
885
2419
2232
2045
1670
4002
3693
3383
2763
1725
1725
1725
1725
3168
3168
3168
3168
5241
5241
5241
5241
1725
1725
1725
1725
1545
1500
1455
1365
1125
975
825
525
Step 2: Determine Actuator Size For
Actuation Thrust
Calculate the actuator cylinder areas required by using
the applicable group of equations in the following tables.
Compare the calculated areas to the corresponding
areas for the actuator size selected in Step 1. Actuator
areas are listed in Table 16-III. If the calculated areas
are less than or equal to the corresponding areas for the
selected actuator, the actuator size is adequate. If the
calculated areas are larger, an actuator with cylinder
areas larger than the calculated areas must be selected.
When determining the required actuator size, various
service conditions should be considered. For each
sizing equation, the conditions to be considered for that
equation are listed with the equation. Each equation
should be evaluated for each listed condition that will
actually occur. The condition numbers refer to the
following list.
Service Conditions to be considered:
1. P1 and P2 for flow conditions. If more than one flow
condition will occur, each should be evaluated.
2. P1 and P2 at shutoff. If more than one set of
pressures will occur during shutoff, each set of
pressures should be evaluated. The possibility of
P2 dropping to atmospheric pressure (0 psig) should
be considered. Pressures used to bench test the
valve should also be considered.
3. P1 and P2 equal to the maximum value of P1. This
condition may occur if the pipeline is pressurized
and the pipe downstream from the valve is blocked.
For this condition, set RSL= 0 in the sizing equations.
4. P1 and P2 equal to 0. This condition will occur if the
pipeline is depressurized. This condition will also
occur during bench testing of the valve. For this
condition, set RSL= 0 in the sizing equations.
NOTES:
1. On valves larger than 24-inch, the weight of the plug
may need to be accounted for; contact factory.
2. A negative number calculated for AL or AU indicates
that the smallest available actuator will work for the
condition being evaluated.
3. For valves with a trim number smaller than the plug
stem diameter, AS-AStem will be a negative number.
In this case, the negative sign must be retained
during the sizing calculations.
Table 16-VII: Actuator Sizing - Standard Globe valves with Unbalanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
stroke valve from full open to
30 percent open
Equation
AU >
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-closed
(air-to-open)
AU >
P1Astem - SFC30 + FP
PS
P2 AS - P1(AS - Astem) - SE + FP + RSL
PS
1 ( with RSL = 0 ), 2, 3, 4
lift plug off seat and stroke valve
from closed to 30 percent open
AL >
P1 (AS - Astem) - P2AS + SFC30 + FP
PS
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
Flow-over
stroke valve from full open to 30
percent open
- P1Astem + SR + FP
AL > z
PS
AU >
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-open
(air-to-close)
AU >
1 ( with RSL = 0 ), 2, 3, 4
lift plug off seat
AL >
2, 3, 4
stroke valve from closed to 30
percent open
1, 3, 4
AL >
P1 Astem + SF030 + FP
PS
(16.9)
(16.10)
(16.11)
(16.12)
(16.13)
P2 AS - P1 (AS - Astem) + SR + FP + RSL
(16.14)
PS
P1(AS - Astem) - P2 AS - SR + FP
PS
P1(AS - Astem) - P2 AS - SF030 + FP
PS
(16.15)
(16.16)
16-5
Table 16-VIII: Actuator Sizing - Standard Globe Valves with Unbalanced Trim
(and Class 150 to 600 MegaStream)
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
stroke valve closed and provide
tight shutoff
Equation
AU >
P1AS - P2(AS - Astem) - SE + FP + RSL
PS
1 ( with R SL = 0 ), 2, 3, 4
lift plug off seat and stroke valve
from closed to 30 percent open
Flow-under
Fail-closed
(air-to-open)
AL >
PS
1, 2, 3, 4
stroke valve full open
AL >
1, 3, 4
Fail-open
(air-to-close)
P2 (AS - Astem) - P1AS+ SFC30 + FP
stroke valve closed and provide
tight shutoff
1 ( with R SL = 0 ), 2, 3, 4
AU >
- P2Astem + SR + FP
(16.17)
(16.18)
(16.19)
PS
P1AS - P2(AS - Astem) + SR + FP + RSL
PS
(16.20)
Table 16-IX: Actuator Sizing - ChannelStream and CavControl Valves with Unbalanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
stroke valve closed and provide
tight shutoff
Fail-closed
(air-to-open)
Flow-over
Equation
AU >
PS
1 ( with R SL = 0 ), 2, 3, 4
lift plug off seat and stroke valve full
open
AL >
1, 2, 3, 4
stroke valve closed and provide
tight shutoff
Fail-open
(air-to-close)
P2AR - P1(AR - Astem) - SE + FP + RSL
1 ( with R SL = 0 ), 2, 3, 4
lift plug off seat and stroke valve full
open
1, 2, 3, 4
AU >
AL >
P1 (AR - Astem) - P2AR+ SR + FP
PS
P2AR - P1(AR - Astem) + SR + FP + RSL
PS
P1 (AR - Astem) - P2AR- SE + FP
PS
(16.21)
(16.22)
(16.23)
(16.24)
Table 16-X: Actuator Sizing - Tiger-Tooth and High Pressure MegaStream Valves with Unbalanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
Equation
stroke valve closed
AU >
1, 3, 4
provide tight shutoff
Fail-closed
(air-to-open)
AU >
2, 3, 4
lift plug off seat
AL >
Flow-under
2, 3, 4
stroke valve full open
AL >
1, 3, 4
stroke valve closed
Fail-open
(air-to-close)
1, 3, 4
provide tight shutoff
2, 3, 4
16-6
AU >
AU >
P1AR - P2 (AR - Astem) - SE + FP
PS
P1AS - P2(AS - Astem) - SE + FP + RSL
PS
P2 (AS - Astem) - P1AS + SE + FP
PS
P2 (AR - Astem) - P1AR + SR + FP
PS
P1AR - P2 (AR - Astem) + SR + FP
PS
(16.25)
(16.26)
(16.27)
(16.28)
(16.29)
P1AS - P2 (AS - Astem) + SR + FP + RSL
(16.30)
PS
Step 3: Determine Spring Size
If it will be necessary for the valve to stroke open or
closed upon loss of air supply pressure, the fail-safe
spring must be sized. The required spring force is
calculated by using the applicable equations in the
following tables. Each sizing equation should be evaluated for the listed conditions that will actually occur. The
condition numbers refer to the service conditions listed
in step 2.
After the required spring force is calculated, it must be
compared to the standard spring force for the actuator
selected in steps 1 and 2. This spring force is listed in
Table 16-VI. If the required spring force is less than the
standard spring force of the selected actuator, a stan-
dard spring will be sufficient. If the required spring
force is greater than that of a standard spring force,
compare the required spring with the dual (or heavyduty) spring force for the same size actuator (see Table
16-VI). If the dual spring force is larger than the required
spring force, the dual spring should be used. If the dual
spring force is not large enough, a volume tank or larger
actuator will be required. Section 19 contains volume
tank sizing information.
If the spring or actuator size selected to provide sufficient spring force is different from that used during step
2, the calculations of step 2 must be verified using the
new spring or actuator information.
Table 16-XI: Spring Sizing - Standard Globe valves with Unbalanced Trim
(and Class 150 to 600 MegaStream)
Valve
Orientation
Fail
Action
Spring to . . .
Service Condition
stroke valve from full open to
30 percent open
Fail-closed
(air-to-open)
Equation
SFC30 > P1Astem + FP
(16.31)
SE > P2 AS - P1 (AS - Astem) + FP + RSL
(16.32)
SR > P1 (AS - Astem) - P2 AS + FP
(16.33)
SFO30 > P1(AS - Astem) - P2 AS + FP
(16.34)
SE > - P1Astem + FP
(16.35)
SFC30 > P2Astem + FP
(16.36)
SE > P1AS - P2 (AS - Astem) + FP + RSL
(16.37)
SFO30 > P2(AS - Astem) - P1AS + FP
(16.38)
SE > - P2Astem + FP
(16.39)
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
1 ( with RSL = 0 ), 2, 3, 4
lift plug off seat
Flow-over
2, 3, 4
Fail-open
(air-to-close)
stroke valve from closed to 30
percent open
1, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
stroke valve from full open to 30
percent open
Fail-closed
(air-to-open)
1, 3, 4
stroke valve closed and provide
tight shutoff
1 ( with RSL = 0 ), 2, 3, 4
Flow-under
lift plug off seat and stroke valve
from closed to 30 percent open
Fail-open
(air-to-close)
1, 2, 3, 4
stroke valve full open
1, 3, 4
16-7
Table 16-XII: Spring Sizing - ChannelStream and CavControl with Unbalanced Trim
Valve
Orientation
Fail
Action
Fail-closed
(air-to-open)
Spring to . . .
Service Condition
stroke valve closed and provide
tight shutoff
Equation
SE > P2 AR - P1 (AR - Astem) + FP + RSL
(16.40)
SR > P1 (AR - Astem) - P2 AR + FP
(16.41)
SE > P1(AR - Astem) - P2 AR + FP
(16.42)
1 ( with RSL = 0 ), 2, 3, 4
lift plug off seat
Flow-over
Fail-open
(air-to-close)
2, 3, 4
stroke valve full open
1, 3, 4
Table 16-XIII: Spring Sizing - Tiger-Tooth and High Pressure MegaStream Valves
with Unbalanced Trim
Valve
Orientation
Fail
Action
Spring to . . .
Service Condition
Equation
stroke valve closed
Fail-closed
(air-to-open)
SE > P1AR - P2 (AR - Astem) + FP
(16.43)
SE > P1AS - P2 (AS - Astem) + FP + RSL
(16.44)
SR > P2 (AS - Astem) - P1AS + FP
(16.45)
SE > P2(AR - Astem) - P1AR + FP
(16.46)
1, 3, 4
provide tight shutoff
2, 3, 4
Flow-under
lift plug off seat
Fail-open
(air-to-close)
2, 3, 4
stroke valve full open
1, 3, 4
16-8
Linear Actuator Sizing,
Pressure-balanced Trim
Introduction
As noted in the procedure for unbalanced trim, in throttling services three questions must be answered:
1. Will the actuator handle the throttling differential
pressure?
2. Will the actuator provide sufficient thrust to overcome application pressures to open or close the
valve, and generate enough seat loading for tight
shutoff with the given air supply pressure?
3. Will the spring fail the valve in the proper direction?
ASl = Sleeve area, in2 (see Table 16-XIV or 16XV)
When an actuator’s stroke length exceeds the longest
stroke length shown for that size actuator in Table 16-VI,
the actuator will not have a spring. For actuators without
a spring, SE= SR= 0.
The areas of the seat, AS, and the seat retainer bore, AR,
are calculated using the following equations. Note that
the area of the seat retainer bore is not used when sizing
actuators for valves with standard trim or when sizing
actuators for Class 150 through 600 MegaStream valves.
With on/off services, only questions 2 and 3 must be
answered.
AS
The equations in this section use the following variables:
AL = Lower cylinder area, in2
AU = Upper cylinder area, in2
AS = Area of the seat, in2 (see Table 16-XIV or
equation 16.47)
Astem = Plug stem cross-sectional area, in2 (see
Table 16-XIV or equation 16.49)
AR = Area of the seat retainer bore, in2 (see
equation 16.48)
obO = Off-balance area tending to open the valve,
in2; obO = ASl - AS (see Table 16-XIV)
obC = Off-balance area tending to close the valve,
in2; obC= ASl - Astem - AS (see Table 16-XIV)
P1 = Pressure on upstream side of the valve, psig
P2 = Pressure on downstream side of the valve,
psig
PS = Air supply pressure, psig
SE = Spring force with the spring extended to full
stroke, lbs (see Table 16-VI)
SR = Spring force with the spring fully retracted,
lbs (see Table 16-VI)
SFC30 = Spring force at 30% of stroke in fail-closed
actuators, lbs (see equation 16.50)
SFO30 = Spring force at 30% of stroke in fail-open
actuators, lbs (see equation 16.51)
FP = Packing friction, lbs (see Table 16-V)
FS = Pressure balance seal friction, lbs (see Table
16-XVI)
RSL = Required seat load to achieve desired
shutoff, lbs (see equation 16.52)
AR =
=
πdS2
4
π(dS + 0.125)2
4
(16.47)
(16.48)
Where:
dS = The seat orifice diameter, in (Trim Number)
dS = T N + 0.125 for ChannelStream and CavControl
The plug stem cross-sectional area, Astem, is calculated
using the following equation:
Astem =
πdstem2
4
(16.49)
Where:
dstem = The plug stem diameter, in (see Table 16XIV)
The spring forces at 30 percent of stroke in fail-closed
and fail-open actuators, SFC30 and SFO30, are calculated
using the following equations:
SFC30 = SE + RS(0.30) S
(16.50)
SFO30 = SR - RS(0.30) S
(16.51)
Where:
RS =Spring rate, lb/in (see Table 16-VI)
S =Stroke length, inches
The required seat load, RSL, is calculated using the
following equation:
RSL = πdCLS
(16.52)
Where:
LS =Seat load per circumferential inch to achieve
16-9
TABLE 16-XIV: Standard Pressure-balanced Valve/Actuator Data (inches)
Valve Rating Full Area Seat
Stem
Stem
Sleeve
Size
Class
Trim
Area
Dia.
Area
Area
(inches)
Size
(sq. in.) (sq. in.) (sq. in.) (sq. in.)
Off-balance Area sq.in. Standard
Flow Under Flow Over
To Close
To Open
Stroke
Actuator (inches)
Size
2
2
2
600
1500
2500
1.62
1.62
1.25
2.07
2.07
1.23
.562
.562
.562
.248
.248
.248
2.58
2.41
1.55
.26
.09
.07
.51
.34
.32
25
25
25
1
1
1
3
3
3
600
1500
2500
2.62
2.62
2.0
5.41
5.41
3.14
.875
.875
.875
.601
.601
.601
6.77
6.49
3.86
.76
.48
.12
1.36
1.08
.72
50
100
100
1.5
2
1.5
4
4
4
600
1500
2500
3.5
3.5
2.62
9.62
9.62
5.41
.875
1.125
1.125
.601
.994
.994
11.41
11.41
6.77
1.19
.80
.37
1.79
1.79
1.36
50
100
100
2
2
2
6
6
6
6
150
600
1500
2500
5.0
5.0
5.0
4.0
19.63
19.63
19.63
12.57
1.125
1.5
1.5
1.5
.994
1.77
1.77
1.77
22.69
23.76
22.69
15.03
2.06
2.36
1.29
.69
3.06
4.13
3.06
2.46
50
100
100
100
2.5
2.5
2.5
2.5
8
8
8
600
1500
2500
6.25
6.25
5.0
30.68
30.68
19.63
1.5
2.0
2.0
1.77
3.14
3.14
35.78
35.78
23.76
3.33
1.96
.99
5.10
5.10
4.13
100
100
100
3
4
4
10
10
10
600
1500
2500
8.0
8.0
6.25
50.27
50.27
30.68
2.0
2.5
2.5
3.14
4.91
4.91
58.36
58.36
37.12
4.95
3.18
1.53
8.09
8.09
6.44
100
100
100
3
4
4
12
12
12
600
1500
2500
9.5
9.5
8.0
70.88
70.88
50.27
2.5
2.5
2.5
4.91
4.91
4.91
78.54
78.54
56.75
2.75
2.75
1.57
7.66
7.66
6.48
100
100
100
4
4
4
14
14
14
150
600
1500
11.0
11.0
11.0
95.03
95.03
95.03
2.5
3.0
3.0
4.91
7.07
7.07
108.43
108.43
103.87
8.49
6.33
1.77
13.40
13.40
8.84
100
100
100
4
4
4
16
16
600
1500
12.75
12.75
127.68
127.68
3.0
3.0
7.07
7.07
140.50
137.89
5.75
3.14
12.82
10.21
100
100
4
4
Trim Type
dC=
Standard
MegaStream
Tiger-Tooth
Trim Number
CavControl
ChannelStream
Trim Number +
0.125 inch
desired shutoff, lbs/in (see Table 8-II)
dC =The diameter of the seating contact surface, in
(see the following table)
Step 1: Determine Actuator’s Maximum
Allowable Throttling Pressure Drop
Refer to Table 16-XIV to find the standard actuator for
the given body size.
Determine the maximum allowable throttling pressure
drop (∆Pa) that the selected actuator can handle by
using equations (16.53) and (16.54):
Air-to-open, flow-over or air-to-close, flow-over:
∆Pa =
ACJO
obO
(16.53)
Air-to-open, flow-under or air-to-close, flow-under:
∆Pa =
ACJC
obC
(16.54)
Where:
∆Pa = Maximum allowable throttling pressure drop,
psi
AC = Area of cylinder actuator, square inches
(see Table 16-III; for air-to-open flow use
lower cylinder area; for air-to-close flow use
upper cylinder area))
obC = Off-balance area tending to close the valve,
in2; obC= ASl - Astem - AS (see Table 16-XIV)
obO = Off-balance area (sq.in.) tending to open the
valve obo= ASl - AS (see Table 16-XIV)
JO = Air supply adjustment factor for flow-over
16-10
(see Table 16-II)
JC = Air supply adjustment factor for flow-under
(see Table 16-II)
Compare the maximum allowable throttling pressure
drop to the actual pressure drop. If the ∆Pactual is less
than ∆Pa, the selected actuator is sufficient. However,
if the ∆Pactual is greater than ∆Pa, the next larger actuator
size should be chosen and the above calculation should
be repeated.
Step 2: Determine Actuator Size For
Actuation Thrust
Calculate the actuator cylinder areas required by using
the applicable equations in the following tables. Compare the calculated areas to the corresponding areas
for the actuator size selected for the throttling drop.
These areas are listed in Table 16-III. If the calculated
areas are less than or equal to the corresponding areas
for the selected actuator, the actuator size is adequate.
If the calculated areas are larger, an actuator with lower
and upper cylinder areas larger than the calculated
areas must be selected.
When determining the required actuator size, various
service conditions should be considered. For each
sizing equation, the conditions to be considered for that
equation are listed with the equation. Each equation
should be evaluated for each listed condition that will
actually occur. The condition numbers refer to the
following list.
Service Conditions to be considered:
1. P1 and P2 for flow conditions. If more than one flow
condition will occur, each should be evaluated.
2. P1 and P2 at shutoff. If more than one set of
pressures will occur during shutoff, each set of
pressures should be evaluated. The possibility of
P2 dropping to atmospheric pressure (0 psig) should
be considered.
3. P1 and P2 equal to the maximum value of P1. This
condition may occur if the pipeline is pressurized
and the pipe downstream from the valve is blocked.
4. P1 and P2 equal to 0. This condition will occur if the
pipeline is depressurized. This condition will also
occur during bench testing of the valve.
NOTES:
1. On valves larger than 24-inch, the weight of the plug
may need to be accounted for; contact factory.
2. A negative number calculated for AL or AU indicates
that the smallest available actuator will work for the
condition being evaluated.
Table 16-XV: Pressure-balanced Sleeve Area
ChannelStream
and CavControl
ASI = AR = AS
Valves other than ChannelStream and
CavControl not listed in Table 16-XIV
Pressure Class
ASI
150 - 600
(1.10) AS + Astem
900 - 1500
(1.05) AS + Astem
2500
(1.03) AS + Astem
Table 16-XVI: Seal Friction Forces
Type of Seal
Seal Friction, FS, (lbs)
Teflon
FS = 58(TN) + 12
O-Ring and Spring
Energized Elastomer
FS = 14(TN) + 0.029(P1 - P2)
Muskegon Piston Rings
FS = 0.00613(TN)(P1 - P2)
NiResist Piston Rings
FS = 0.0613(TN)(P1 - P2)HS
Where:
TN = Trim Number
HS = Seal height
= 0.13 for TN = 1.00 to TN = 2.25
= 0.19 for TN = 2.62 to TN = 5.00
= 0.25 for TN = 5.50 to TN = 9.50
= 0.38 for TN = 11.00 to TN = 22.00
16-11
Table 16-XVII: Actuator Sizing - Standard Globe Valves with Pressure-balanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
stroke valve from full open to
30 percent open
Equation
AU >
P1Astem - S FC30 + FP + FS
PS
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-closed
(air-to-open)
1 (with RSL = 0), 2, 3, 4
lift plug off seat and stroke valve
from closed to 30 percent open
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
Flow-over
stroke valve from full open to 30
percent open
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-open
(air-to-close)
1 (with RSL = 0), 2, 3, 4
lift plug off seat and open valve
from closed to 30 percent open
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
AU >
AL >
AL >
AU >
AU >
AL >
AL >
(16.55)
P1(obO) - P2(obC) - SE + FP + F S + R SL
(16.56)
PS
P2(obC) - P 1(obO) + SFC30 + FP + FS
PS
- P1Astem + SR + FP + F S
PS
P1 Astem + SFO30 + FP + FS
PS
(16.57)
(16.58)
(16.59)
P1(obO) - P 2(obC) + SR + FP + FS + RSL
(16.60)
PS
P2(obC) - P1(obO) - SFO30 + FP + FS
PS
- P1Astem - SE + FP + F S
PS
(16.61)
(16.62)
Table 16-XVIII: Actuator Sizing - Standard Globe Valves (and Class 150 to 600
MegaStream)
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
stroke valve from full open to
30 percent open
Equation
AU >
P2Astem - S FC30 + FP + FS
PS
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-closed
(air-to-open)
1 (with RSL = 0), 2, 3, 4
lift plug off seat and stroke valve
from closed to 30 percent open
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
Flow-under
stroke valve from full open to 30
percent open
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
Fail-open
(air-to-close)
1 (with RSL = 0), 2, 3, 4
lift plug off seat and open valve
from closed to 30 percent open
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
16-12
AU >
AL >
AL >
AU >
AU >
AL >
AL >
(16.63)
P2(obO) - P1(obC) - SE + FP + F S + R SL
(16.64)
PS
P1(obC) - P 2(obO) + SFC30 + FP + FS
PS
- P2Astem + SR + FP + F S
PS
P2Astem + SFO30 + FP + FS
PS
(16.65)
(16.66)
(16.67)
P2(obO) - P 1(obC) + SR + FP + FS + RSL
(16.68)
PS
P1(obC) - P2(obO) - SFO30 + FP + FS
PS
- P2Astem - SE + FP + F S
PS
(16.69)
(16.70)
Table 16-XIX: Actuator Sizing - ChannelStream and CavControl Valves
with Pressure-balanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
Equation
stroke valve closed and provide
tight shutoff
Fail-closed
(air-to-open)
AU >
lift plug off seat and stroke valve full
open
stroke valve closed and provide
tight shutoff
Fail-open
(air-to-close)
PS
1 (with RSL = 0), 2, 3, 4
1, 2, 3, 4
Flow-over
P2Astem - S E + FP + FS + RSL
AU >
1 (with RSL = 0), 2, 3, 4
lift plug off seat and stroke valve full
open
1, 2, 3, 4
AL >
AL >
- P2Astem + SR + FP + F S
PS
P2Astem + SR + FP + FS + RSL
PS
- P2Astem - SE + FP + FS
PS
(16.71)
(16.72)
(16.73)
(16.74)
Table 16-XX: Actuator Sizing - Tiger-Tooth and High Pressure MegaStream Valves
with Pressure-balanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Service Condition
Equation
stroke valve closed
AU >
1, 3, 4
provide tight shutoff
Fail-closed
(air-to-open)
AU >
2, 3, 4
lift plug off seat
2, 3, 4
AL >
stroke valve full open
AL >
1, 3, 4
Flow-under
stroke valve closed
AU >
1, 3, 4
provide tight shutoff
Fail-open
(air-to-close)
2, 3, 4
AU >
lift plug off seat
2, 3, 4
AL >
stroke valve full open
1, 3, 4
AL >
P2(ASl - AR) - P1(ASl - AR - Astem) - SE + FP + FS
PS
(16.75)
P2(ASl - AS) - P1(ASl - AS - Astem) - SE + FP + FS + RSL
(16.76)
PS
P1(ASl - AS - Astem) - P2(ASl - AS) + SE + FP + FS
PS
P1(ASl - AR - Astem) - P2(ASl - AR) + SR + FP + FS
PS
P2(ASl - AR) - P1(ASl - AR - Astem) + SR + FP + FS
PS
(16.77)
(16.78)
(16.79)
P2(ASl - AS) - P1(ASl - AS - Astem) + SR + FP + FS + RSL
(16.80)
PS
P1(ASl - AS - Astem) - P2(ASl - AS) - SR + FP + FS
PS
P1(ASl - AR - Astem) - P2(ASl - AR) - SE + FP + FS
PS
(16.81)
(16.82)
16-13
Step 3: Determine Spring Size
If the valve is required to stroke open or closed upon
loss of air supply pressure, the actuator fail-safe spring
must be sized. The required spring force is calculated
by using the applicable equations in the following tables.
For each sizing equation, the conditions to be considered for that equation are listed. Each equation should
be evaluated for the listed conditions that will actually
occur. The condition numbers refer to the service
conditions listed in Step 2.
After the required spring force is calculated, it must be
compared to the standard spring force for the actuator
selected in steps 1 and 2. This spring force is listed in
Table 16-VI. If the required spring force is less than the
standard spring force for the selected actuator, a standard spring will be sufficient. If the required spring force
is greater than that of a standard spring, compare the
required spring force with the dual (or heavy-duty)
spring force for the same size actuator (see Table 16VI). If the dual spring force is larger than the required
spring force, the dual spring should be used. If the dual
spring force is not large enough, a volume tank or larger
actuator will
be required. Section 19 contains
volume tank sizing information.
If the spring or actuator size selected to provide sufficient spring force is different from that used during step
2, the calculations of step 2 must be verified using the
new spring or actuator information.
Table 16-XXI: Spring Sizing - Standard Globe valves with Pressure-balanced Trim
(and Class 150 to 600 MegaStream)
Valve
Orientation
Fail
Action
Spring to . . .
Service Condition
stroke valve from full open to
30 percent open
Fail-closed
(air-to-open)
1, 3, 4
stroke valve closed from 30 percent
open and provide tight shutoff
1 ( with RSL = 0 ), 2, 3, 4
Flow-under
lift plug off seat and stroke valve
from closed to 30 percent open
Fail-open
(air-to-close)
1, 2, 3, 4
stroke valve from 30 percent open
to full open
1, 3, 4
stroke valve from full open to 30
percent open
Fail-closed
(air-to-open)
1, 3, 4
stroke valve closed and provide
tight shutoff
1 ( with RSL = 0 ), 2, 3, 4
Flow-over
lift plug off seat and stroke valve
from closed to 30 percent open
Fail-open
(air-to-close)
1, 2, 3, 4
Equation
SFC30 > P2Astem + FP+ FS
(16.83)
SE > P2(obO) - P1(obC) + F P + FS + R SL
(16.84)
SFO30 > P1(obC) - P2(obO) + FP + FS
(16.85)
SE > - P2Astem + FP + F S
(16.86)
SFC30 > P1Astem + FP + F S
(16.87)
SE > P1(obO) - P2(obC) + F P + FS + R SL
(16.88)
SFO30 > P2(obC) - P1(obO) + FP + FS
(16.89)
SE > - P1Astem + FP + F S
(16.90)
stroke valve full open
1, 2, 3, 4
Table 16-XXII: Spring Sizing - ChannelStream and CavControl with Pressure-balanced Trim
Valve
Orientation
Fail
Action
Fail-closed
(air-to-open)
Flow-over
16-14
Fail-open
(air-to-close)
Spring to . . .
Service Condition
stroke valve closed and provide
tight shutoff
Equation
SE > P2 Astem + FP + FS+ RSL
(16.91)
SE > - P2 Astem + FP + FS
(16.92)
1 ( with RSL = 0 ), 2, 3, 4
lift plug off seat and stroke valve full
open
1, 2, 3, 4
Table 16-XXIII: Spring Sizing - Tiger-Tooth and High Pressure MegaStream Valves
with Pressure-balanced Trim
Valve
Orientation
Fail
Action
Actuator to . . .
Equation
Service Condition
stroke valve closed
Fail-closed
(air-to-open)
SE > P2(ASl - AR) - P1(ASl - AR - Astem) + FP + FS
(16.93)
SE > P2(ASl - AS) - P1(ASl - AS - Astem) + FP + FS + RSL
(16.94)
SR > P1(ASl - AS - Astem) - P2(ASl - AS) + FP + FS
(16.95)
SE > P1(ASl - AR - Astem) - P2(ASl - AR) + FP + FS
(16.96)
1, 3, 4
provide tight shutoff
2, 3, 4
Flow-under
lift plug off seat
Fail-open
(air-to-close)
2, 3, 4
stroke valve full open
1, 3, 4
Linear Actuator Sizing,
Guardian II Metal Bellows Seal
Introduction
The following data must be used when sizing actuators
for Guardian II metal bellows valves. This information
along with the previous equations listed in Sizing and
Selection section 16 will be combined for accurate
sizing. See Table XXIV for the initial sizing information
needed. While sizing, the actuator pressure limits in
Table XXV must not be exceeded. For valve and
actuator combinations not listed, the actuator pressure
limit is 150 psig.
Table 16-XXIV: Guardian II Bellows Valve
Actuator Sizing Information
Max. Effective Relaxed Bellows
Valve
ANSI
Stroke
Bellows Position Spring
Size Pressure
Length
Area (in. from Rate
(inches) Class
(inches) (sq. in.)
seat)
(lb/in)
1
⁄2, 3⁄4, 1 150, 300
11⁄2, 2 150, 300
3
150, 300
4, 6
150
4, 6
300
8
150
8
300
0.5
1.0
1.5
2.5
2.5
3.0
3.0
0.75
1.35
1.35
2.38
2.18
4.53
4.75
0
0
0.25
0
0
0
0
36
26
26
15
42
20
112
To determine actuator spring forces, the stroke length
of a valve must be known. Many Guardian II stroke
lengths are given in Table XXVI. For the trims not listed
in Table
Table 16-XXV
Guardian II Actuator Pressure Limits
Valve
Size
(inches)
ANSI
Pressure
Class
Actuator
Size
(sq. in.)
Max. Actuator
Pressure
(psig)
6
6
8
8
8
8
300
300
150
150
300
300
200
300
200
300
200
300
100
60
100
60
100
60
XXVI, the stroke length is determined by comparing the
maximum stroke length listed in Table XXIV to the
stroke length of a standard Mark One valve that is the
same size and has the same trim. The actual stroke
length of the valve with a Guardian II bellows seal will be
the shorter of these two stroke lengths.
Fluid pressure inside the valve acts on the effective
bellows area. This area is listed in Table XXIV and
should be substituted for the actuator stem area in the
actuator sizing equations.
The relaxed position of the bellows is the distance from
the seat where the bellows is not in tension or
16-15
compression. The metal bellows acts as a spring that
is compressed or stretched as the plug is moved from
the relaxed position. To account for the spring force of
the bellows, it is necessary to add a term to the sizing
equations of Section 16 of the Sizing & Selection
manual. The term is added to the numerator on the right
side of the equations for actuator area and is added to
the right side of equations for spring force. This additional
term is designated SB. For equations used to determine
the actuator or spring size required to close the valve,
SB is calculated by using Equation 1.
SB = RB(PR-PA)
Table 16-XXVI:
Cv Data (=% Trim, Flow Over)
Valve Size
(inches)
1
⁄2
3
⁄4
(Equation 1)
1
For equations used to determine the actuator or spring
size required to open the valve, SB is calculated by
using Equation 2.
11⁄2
SB = RB(PA-PR)
(Equation 2)
Where:
SB = Spring force of the metal bellows, lbs.
PA = Actual position of the plug, in. (If the
equation
from Sizing & Selection section
16 determines the force required to
move the plug
through
a
range of stroke values, use the
position that gives the largest value for SB).
2
3
4
PR = Relaxed position of the plug, in.
(See Table XXIV).
6
RB = Spring rate of the metal bellows, lb/in.
(See Table XXIV).
8
Trim
Number
Stroke
(inches)
Full
Cv
.50
.31
.72
.50
.31
.81
.50
.31
1.25
1.00
.81
1.62
1.25
1.00
.81
2.62
1.62
3.50
2.25
5.00
3.50
6.25
5.00
.50
.50
.50
.50
.50
.50
.50
.50
1.00
.75
.75
1.00
1.00
.75
.75
1.50
1.50
2.50
2.00
2.50
2.50
3.00
3.00
4.2
2.3
7.5
5.4
2.6
11.0
5.7
2.6
30
22
18
44
33
23
19
107
49
206
113
405
236
698
474
Table 16-XXVII: Examples of Modifications to Actuator Sizing Equations
Equation
16.9
16.10
16.11
16.12
Modified Equation
AU >
AU >
AL >
AL >
P1Abellows - SFC30 + FP + SB
SB Equation
SB Evaluation Position (PA)
1
30 percent open
(0.3 X Stroke Length)
1
On seat
(0.0 inches)
2
30 percent open
(0.3 X Stroke Length)
2
Full open
(Stroke Length)
PS
P2 AS - P1(AS - Abellows) - SE + FP + RSL + SB
PS
P1 (AS - Abellows) - P2AS + SFC30 + FP +SB
PS
- P1Abellows + SR + FP + SB
PS
16.31
SFC30 > P1Abellows + FP +SB
1
30 percent open
(0.3 X Stroke Length)
16.32
SE > P2 AS - P1 (AS - Abellows) + FP + RSL + SB
1
On seat
(0.0 inches)
16-16
Rotary Actuator Sizing,
Valdisk and Valdisk 150
Introduction
To select an actuator for a Valdisk or Valdisk 150 high
performance butterfly valve, five sequential steps are
necessary:
1. Determine the shaft orientation and actuator stiffness requirements.
2. Calculate the seating and breakout torque.
3. Calculate the dynamic torque.
4. Select an actuator capable of providing sufficient
torque to overcome the seating/breakout torque
and dynamic torque based on available air supply.
5. If a fail-open or fail-close action is required, select
an actuator capable of providing sufficient torque to
overcome the seating/breakout torque and dynamic torque based on available spring torque.
Step 1: Determine the Shaft Orientation
Because the disc in a Valdisk or Valdisk 150 is double
offset, when the shaft is oriented upstream the dynamic
torque created by the process fluid will force the disc
into the seat. A disc with the shaft oriented downstream
will move toward the open position when near the seat.
As a general rule, a valve that is required to fail-close on
loss of instrument air supply usually has the shaft
upstream. A valve which is required to fail open has the
shaft downstream.
The above rule applies to all applications where the
flowing fluid is a gas. On liquid applications with the
shaft upstream, the actuator must be adequately stiff to
prevent the disc from closing too rapidly, thus eliminating any potential pressure surge condition which would
result in water hammer. To determine if the actuator
has sufficient stiffness, calculate the following:
∆P (max)
Actuator Stiffness (required) =
(16.97)
Sup. Press.
Compare the required actuator stiffness with the maximum actuator stiffness values found in Table 16-XXVIII
(according to valve size). Shaft upstream on a failclosed liquid service can be used, provided the required
stiffness does not exceed the actuator stiffness (max)
for the actuator size selected. Note that in all cases the
standard actuator size for a given valve size is indicated
first in the chart. A larger actuator size may be required
to ensure adequate stiffness. If the required stiffness
exceeds all those indicated for the actuator sizes available for a given valve size, shaft downstream orientation is required.
Step 2: Find the Seating and Breakout
Torque
Using table 16-XXX and the following equations, calculate the seating and breakout torque.
Table 16-XXVIII: Actuator Stiffness (max.) for Shaft Upstream, Liquid Applications
Valve Size
(inches)
2
3
4
6
8
10
12
14
16
18
20
24
Actuator Size
Standard
25
3.1
3.1
1.7
0.81
Standard
50
8.8
4.3
2.4
1.3
Standard
100
Standard
200
Toggle-link
100
Toggle-link
200
6.9
6.0
3.4
2.4
1.4
0.98
0.84
0.53
0.39
15.9
13.8
7.8
5.5
3.2
2.2
1.9
1.2
0.87
13.2
7.5
5.3
3.1
2.16
1.85
1.17
.86
30.4
17.2
12.1
7.0
4.8
4.2
2.6
1.9
16-17
Table 16-XXIX: Dynamic Torque Factors vs. Disc Position
Valve
Size
(in.)
Dynamic Torque Factor vs. Disc Position (Degrees Open)
10o
20o
30o
2
A
0
B
0
A
0
B
0
A
0
3
0
0
0
0
0
4
6
0
0
0
0
0
0
0
1
0
1
40o
B
50o
A
0
B
0
A
0
0
1
0
1
0
1
0
60o
B
70o
0
A
0
B
0
2
0
2
0
3
0
2
1
4
1
4
80o
A
0
B
0
0
0
0
0
2
9
1
6
4
17
0
0
6
23
-4
-19
4
19
0
A
90o
B
A
B
8
0
0
0
1
1
2
2
4
3
7
4
12
1
19
-8
28
-23
23
10
12
0
1
1
2
1
2
2
7
2
5
6
13
5
10
9
20
7
16
17
38
8
18
28
61
4
8
46
101
-18
-40
65
144
-55
-121
55
121
14
16
1
2
3
4
3
4
10
12
6
8
18
23
15
19
28
36
22
27
54
67
25
32
85
106
12
15
142
177
-56
-69
201
250
-168
-211
168
211
18
5
10
10
29
19
54
44
83
64
156
73
247
34
411
-161
582
-489
489
20
24
5
7
10
14
10
14
31
42
21
28
58
78
47
64
89
121
68
92
168
227
78
106
264
358
6
50
440
596
-173
-234
623
845
-524
-710
524
710
30
24
49
49
146
97
268
219
414
316
779
365
1230
170
2046
-804
2899
-2436
2436
A = Shaft Downstream
B = Shaft Upstream
NOTE: When degrees of opening are not known, use highest value of Cd for valve size.
Shaft downstream: (Torque required to close valve)
Tst = - TP - TS - ∆PMAX(CBT + COT) - TH
(16.98)
Shaft downstream: (Torque required to open valve)
Tbo = TP + TS + ∆PMAX(CBT - COT) + TH
(16.99)
70 to 80 degrees open, which could result in some
controllability problems. To avoid this, change the shaft
orientation to shaft upstream or limit the disc rotation to
70 degrees.
For gas applications use Table 16-XXX and the following equations to find the required dynamic torque:
Shaft upstream: (Torque required to close valve)
Tst = - TP - TS - ∆PMAX(CBT - COT) - TH
(16.100)
Shaft upstream: (Torque required to open valve)
Tbo = TP + TS + ∆PMAX(CBT + COT) + TH
(16.101)
Where: Tst = Seating torque
Tbo = Breakout required
TP = Packing torque
TS = Seat torque
∆PMAX = Maximum pressure drop at shutoff
CBT = Bearing torque factor
COT = Off-balance torque factor
TH = Handwheel torque. TH = O without
handwheel (See Table 16 - XXXII)
NOTE: Negative values calculated for Tc, Tbo, Tst,
indicate the disc will tend to resist closing. Positive
values indicate the disc will tend to resist opening.
Step 3: Calculate the Dynamic Torque
Since the net torque output of rotary actuators varies as
disc position changes, it may be necessary to find the
dynamic torque on the shaft at various degrees of
opening. This is generally required only when a relatively high actual pressure drop is expected through
part or all of the disc rotation. With the shaft oriented
downstream a torque reversal occurs at approximately
16-18
To close the disc:
TD = - TP - ∆Peff(CBT)
(16.102)
To open the disc:
TD = TP + ∆Peff(CBT)
(16.103)
For liquid applications use Tables 16-XXIX, 16-XXX
and the following equations to find the required dynamic
torque:
To close the disc
TD = -TP - ∆Peff(CBT - Cd)
(16.104)
To open the disc
TD = TP + ∆Peff(CBT - Cd)
(16.105)
Where:
TD = Dynamic torque: (-)values indicate the
disc will resist closing. (+) values indicate
the disc will resist opening.
Cd = Dynamic torque factor from Table 16XXIX for appropriate shaft orientation and
degrees of opening. Use highest Cd value
if degrees of opening are unknown.
∆Peff = ∆P(actual) at the flowing condition at the
operating degrees of opening limited to
∆P (choked)
TP = Packing torque factor, from Table 16-XXX
Table 16-XXX: Static Breakout Torque = Sizing
Valve
Size
(inches)
ANSI
Pressure
Class
2
3
4
6
8
10
12
14
16
18
20
24
30
150,300,600
150,300*
150*
TP = Packing Torque
(in-lb)
(1)
(2)
(3)
(4)
(5)
TS = Seat
Torque
(in-lb)
50
50
57
64
79
79
104
104
122
122
141
141
182
280 477
280 477
333 533
385 590
490 702
490 702
648 870
648 870
753 983
753 983
858 1095
858 1095
1068 1319
350
350
399
448
543
543
691
691
789
789
886
886
1081
63
63
71
81
104
104
151
151
190
190
234
234
342
74
154
270
596
980
1612
2102
4338
5853
6639
9378
11829
19521
(1) TFE or filled TFE V-ring packing
(2) Grafoil packing
(3) Twin Grafoil Packing
(4) Asbestos free packing
CBT = Bearing
Torque Factor
(6)
(7)
COT = Off
Balance
Torque Factor
0.09
0.20
0.48
1.27
2.73
4.46
8.60
11.98
16.61
21.99
35.50
44.78
110.83
0.13
0.30
0.72
1.90
4.10
6.69
12.90
17.97
24.92
32.99
53.25
67.17
166.25
0.20
0.40
0.71
1.66
2.58
4.25
5.55
25.65
34.62
39.27
55.42
65.40
38.49
(5) Braided PTFE packing
(6) Filament wound glass/TFE bearing
(7) 316 stainless steel/solid film lubricant coated bearing and stellite bearings
* For higher pressure class data, consult factory
Table 16-XXXI: Valve/Actuator Compatibility - Valdisk/Valdisk 150
Actuator
Size
(sq.in.)
Spring
Size
STD. 25
STD.
STD. 25
H.D.
STD. 50
STD.
Valves Size (inches)
2
STD. 50
H.D.
STD. 100
STD.
STD. 100
H.D.
STD. 200
STD.
STD. 200
H.D.
3
4
6
8 10 12 14 16 18 20 24 30
NOTE: For Valdisk valve compatibility with Toggle-link actuators, contact factory.
Table 16-XXXII:
Declutchable Handwheel Torque (TH)
Actuator Size
(sq.in.)
Handwheel Torque
(in-lbs)
25
150
50
250
100 - 200
375
16-19
CBT = Bearing torque factor, from Table 16-XXX
∆P(choked) is shown as:
∆P(choked) = FL2 (P1 - FfPV)
(16.106)
Step 5: Select Actuator Based on
Available Spring Torque
Where:
FL = Valves recovery coefficient
P1 = Upstream pressure, psia
Ff = Liquid critical pressure ratio
PV = Vapor pressure of the liquid, psia
If the spring must move the disc to a desired failure
position upon air supply loss, select an actuator from
table 16-XXXIII according to the following criteria.
(Available actuator sizes are indicated in Table 16XXXI.)
Step 4: Determine Actuator Size Based
on
Air Supply
Select an actuator from Table 16-XXXIII with sufficient
net torque to overcome the calculated seating/breakout
and dynamic torque through the full stroke rotation of
the valve based on the available air supply.
After the actuator size has been selected, all gas and
liquid applications with shaft downstream should be
checked for sufficient actuator stiffness. Using the
following equation, calculate corrected air supply:
SC = 0.867Sa - 12.3
Where:
(16.107)
SC = Corrected supply pressure
Sa = Actual supply pressure
Using SC, consult Table 16-XXXIII and confirm that the
actuator size selected has sufficient torque to overcome
the dynamic torque values (calculated from step 3).
Choose a larger actuator size if the torque available
throughout the full stroke rotation is less than the
dynamic torque calculated.
16-20
Finally, check the valve/actuator interface compatibility
in Table 16-XXXI for the actuator chosen.
For fail-closed valves, which do not require tight shutoff
on air failure, the spring must provide sufficient torque
to overcome the calculated dynamic torque through the
full stroke rotation of the valve. For valves requiring tight
shutoff, the spring must also provide sufficient torque at
the 0 degree (closed) position to overcome the required
seating torque.
For fail-open valves, the spring must deliver sufficient
torque at the 90 degrees (closed) position to overcome
the calculated breakout torque. It must also have
sufficient torque to overcome the dynamic torque
throughout the full stroke rotation of the valve.
Should the required torque be greater than the available
springs can provide, a volume tank can be used to
ensure failure on loss of air supply.
For liquid applications with the shaft oriented upstream,
the selected actuator should have adequate stiffness. It
should also provide sufficient torque to overcome the
seating/breakout torque and dynamic torque through
the fall stroke rotation of the valve with the available air
supply and available spring torque, if a failure mode is
required.
Table 16-XXXIII: Net Torque Output of Standard Actuators at Various Supply Pressures (inNOTE: For air-to-open/fail-closed actuators the 0 degreelb)
position shown corresponds to the disc or ball being seated.
For air-to-close/fail-open actuators the 90 degree position shown corresponds to the disc or ball being seated.
Degrees from Fail Position on Air Supply Loss
Actuaor
Size
Supply
Pressure
0
10
20
30
40
50
60
70
80
90
STD 25 with
STD Spring
150
140
120
100
80
60
40
Spring Torque
3013
2755
2397
1986
1574
1163
751
54
3399
3165
2695
2228
1759
1290
821
86
3700
3444
2928
2412
1896
1381
864
125
3907
3631
3080
2530
1979
1428
876
169
4000
3714
3145
2573
2002
1430
858
213
3970
3685
3110
2535
1961
1386
811
254
3811
3531
2972
2414
1856
1298
738
284
3514
3253
2731
2211
1688
1167
645
299
3084
2854
2390
1928
1463
1001
537
293
2532
2339
1962
1577
1191
806
420
262
STD 25 with
HD Spring
150
140
120
100
80
60
Spring Torque
2647
2441
2030
1618
1206
795
440
2973
2738
2270
1802
1333
865
542
3223
2964
2450
1934
1418
902
647
3386
3110
2558
2009
1457
907
749
3448
3162
2590
2020
1448
877
839
3403
3115
2542
1967
1392
818
908
3246
2966
2409
1850
1292
733
945
2976
2716
2195
1673
1151
630
937
2600
2368
1905
1441
978
515
878
2124
1931
1552
1167
781
396
758
STD 50 with
STD Spring
150
140
120
100
80
60
40
Spring Torque
10701
9970
8516
7059
5602
4147
2690
222
11981
11157
9513
7873
6227
4586
2942
343
13015
12114
10318
8515
6716
4913
3111
489
13751
12798
10874
8953
7033
5114
3192
651
14134
13136
11141
9153
7156
5166
3171
816
14089
13083
11075
9073
7062
5058
3049
966
13575
12596
10649
8693
6736
4784
2829
1081
12568
11653
9826
7999
6174
4347
2519
1134
11043
10232
8615
6995
5372
3755
2134
1107
9035
8365
7053
5712
4373
3034
1693
983
STD 50 with
HD Spring
150
140
120
100
80
60
Spring Torque
9774
9044
7591
6133
4678
3223
1148
10898
10074
8430
6790
5148
3505
1428
11781
10880
9083
7281
5481
3681
1726
12380
11425
9502
7585
5660
3741
2026
12651
11652
9657
7668
5671
3680
2304
12533
11527
9519
7516
5508
3501
2529
12000
11021
9073
7117
5163
3209
2662
11036
10122
8300
6473
4646
2821
2667
9648
8837
7216
5597
3974
2356
2511
7850
7183
5865
4527
3186
1846
2167
STD 100 with
STD Spring
150
140
120
100
80
60
40
Spring Torque
26194
24385
20805
17226
13640
10055
6469
704
29415
27397
23329
19271
15200
11139
7077
1049
32022
29784
25330
20859
16399
11929
7472
1461
33847
31459
26685
21914
17153
12391
7624
1913
34730
32253
27303
22368
17413
12472
7526
2370
34559
32069
27104
22119
17133
12159
7181
2783
33234
30831
25983
21134
16296
11447
6605
3088
30711
28446
23921
19394
14878
10350
5829
3225
26943
26936
20932
16920
12915
8901
4893
3135
22035
20378
17119
13808
10485
7167
3851
2775
STD 100 with
HD Spring
150
140
120
100
80
60
Spring Torque
24678
22881
19304
15713
12130
8545
2217
27231
25195
21127
17070
12999
8939
3256
29008
26771
22317
17847
13385
8921
4485
29925
27539
22784
18012
13248
8483
5831
29917
27459
22507
17567
12612
7673
7185
28969
26475
21490
16518
11538
6558
8405
27058
24632
19782
14946
10101
5257
9299
24266
22001
17472
12956
8432
3910
9691
20699
18691
14680
10674
6662
2662
9407
16483
14832
11563
8245
4927
1611
8316
STD 200 with
STD Spring
80
70
60
50
40
30
Spring Torque
27695
24156
20595
17051
13501
9951
704
31132
27119
23091
19072
15043
11022
1049
33903
29480
25069
20643
16227
11808
1461
35838
31134
26406
21696
16969
12253
1913
36820
31916
27014
22126
17223
12328
2370
36663
31730
26813
21876
16952
12015
2783
35280
30501
25699
20897
16109
11307
3088
32620
28139
24656
19173
14703
10219
3225
28633
25670
20697
16724
12760
8785
3135
23416
20206
16926
13646
10357
7071
2775
STD 200 with
HD Spring
80
70
60
50
40
30
Spring Torque
26192
22636
19094
15538
11991
8441
2217
28930
24918
20889
16872
12842
8821
3256
30894
26467
22056
17629
13212
8792
4485
31940
27214
22505
17779
13064
8345
5831
32005
27122
22217
17326
12421
7530
7185
31052
26136
21198
16275
11346
6414
8405
29104
24302
19499
14709
9914
5116
9299
26177
21693
17208
12735
8257
3778
9691
22393
18420
14445
10478
6507
2536
9407
17887
14650
11370
8083
4799
1514
8316
(continued)
16-21
Table 16-XXXIII: (continued)
Net Torque Output of Toggle-link Actuators at Various Supply Press. (in-lb)
NOTE: For air-to-open/fail-closed actuators the 0 degree position shown corresponds to the disc or ball being seated.
For air-to-close/fail-open actuators the 90 degree position shown corresponds to the disc or ball being seated.
Degrees from Fail Position on Air Supply Loss
Actuaor
Size
Supply
Pressure
0
10
20
30
40
50
60
70
80
90
STD 100 with
No Spring
150
140
120
100
80
70
60
55253
51566
44200
36835
29465
25783
22100
50511
47141
40407
33674
26937
23570
20203
48414
45183
38730
32276
25818
22591
19364
47688
44506
38149
31792
25431
22252
19074
47565
44390
38050
31709
25365
22195
19024
47596
44417
38072
31728
25380
22208
19035
47231
44077
37781
31486
25185
22038
18889
46243
43155
36991
30827
24659
21577
18494
44044
41094
35224
29357
23482
20548
17611
40216
37629
32255
26891
21504
18821
16126
STD 100 with
STD 20" Spring
150
140
120
100
80
70
60
Spring Torque
46475
42763
35341
27996
20640
16973
13303
8764
41517
38174
31457
24741
18023
14671
11309
8854
39053
35847
29418
22967
16531
13318
10103
9234
37762
34581
28256
21923
15583
12409
9244
9802
37004
33832
27519
21185
14860
11702
8536
10469
36347
33173
26856
20532
14190
11029
7866
11161
35492
32336
26033
19745
13447
10295
7149
11775
34086
30996
24847
18676
12513
9427
6348
12185
31885
28927
23070
17192
11320
8381
5447
12209
28585
25968
20597
15219
9842
7156
4469
11625
STD 100 with
HD 28" Spring
150
140
120
100
80
70
60
Spring Torque
42482
38800
31452
24099
16745
13077
9405
12677
37897
34552
27836
21123
14404
11049
7687
12491
35540
32330
25881
19447
13009
9794
6576
12773
34250
31070
24741
18393
12063
8889
5722
13330
33432
30261
23946
17627
11299
8139
4976
14038
32745
29572
23233
16909
10577
7414
4249
14783
31840
28686
22399
16095
9798
6652
3506
15436
30466
27398
21227
15068
8900
5815
2735
15804
28395
25457
19580
13712
7836
4900
1962
15699
25370
22747
17376
11997
6620
3930
1242
14847
STD 200 with
No Spring
120
100
80
70
60
50
40
90138
75117
60092
52580
45067
37558
30046
82403
68671
54935
48067
41199
34335
27467
78982
65820
52655
46072
39489
32910
26327
77799
64834
51865
45381
38897
32416
25932
77597
64666
51731
45263
38796
32332
25864
77646
64705
51761
45291
38819
32352
25880
77052
64210
51365
44944
38521
32104
25682
75440
62867
50291
44004
37716
31433
25144
71847
59870
47891
41906
35915
29934
23944
65573
54840
43857
38384
32887
27419
21928
STD 200 with
STD 20" Spring
120
100
80
70
60
50
40
Spring Torque
81372
66376
51346
43764
36215
28722
21221
8764
73545
59778
45950
39076
32250
25402
18554
8854
69667
56415
43301
36736
30176
23601
17039
9234
67776
54835
41931
35455
29000
22546
16083
9802
66960
54063
41139
34705
28245
21806
15359
10469
66341
53409
40508
34045
27602
21140
14689
11161
65317
52467
39606
33203
26775
20364
13944
11775
63265
50725
38139
31846
25573
19282
12999
12185
59683
47718
35730
29737
23761
17770
11784
12209
53947
43167
32194
26720
21229
15758
10272
11625
STD 200 with
HD 28" Spring
120
100
80
70
60
50
40
Spring Torque
77455
62436
47376
39792
32321
24823
17326
12677
69905
56083
42304
35474
28628
21783
14934
12491
66066
52894
39777
33196
26640
20081
13517
12773
64242
51326
38398
31945
25488
19016
12555
13330
63370
50491
37592
31133
24692
18249
11798
14038
62710
49816
36886
30444
23979
17532
11077
14783
61663
48813
35982
29554
23141
16714
10294
15436
59644
47105
34519
28247
21953
15675
9380
15804
56196
44228
32240
26266
20271
14290
8299
15699
50755
39946
28972
23481
18007
12525
7043
14847
STD 200 with
HD 34" Spring
120
100
80
70
60
50
40
Spring Torque
74734
59697
44588
37026
29543
22050
14567
15446
67370
53551
39793
32944
26095
19252
12404
15021
63658
50490
37353
30791
24212
17655
11099
15198
61889
48931
36033
29558
23099
16641
10175
15718
60983
46106
35208
28770
22310
15866
9416
16422
60326
47431
34501
28059
21609
15148
8698
17180
59298
46441
33610
27182
20769
14353
7929
17808
57364
44783
32197
25926
19632
13353
7065
18127
53986
42018
30030
24055
18059
12078
6087
17921
48740
37928
26953
21462
15977
10505
5019
16866
16-22
Rotary Actuator Sizing,
ShearStream
Where:
Tbo = Seating/breakout torque (in-lb) is the torque
required to close and open the valve.
Introduction
To select an actuator for a ShearStream high performance ball valve, three steps are necessary:
1. Determine seating/breakout torques. (Also determine the dynamic torque in liquid applications.)
TP = Packing torque (in-lb) is the torque required to
overcome the friction of the packing on the
shaft. Packing torque varies with packing
material. (See Table 16-XXXVI)
2. Select an actuator capable of providing sufficient
torque to overcome the seating/breakout torque
and dynamic torque based on available air supply.
TS = Seat torque (in-lb) is the torque required to
overcome the friction of the seat on the ball.
(See Table 16-XXXVI)
3. If a failure action is required, select an actuator
capable of providing sufficient torque to overcome
the seating/breakout torque and dynamic torque
based on available spring torque.
Step 1: Determine Seating/Breakout
Torques.
Normally, ShearStream valves are installed with the
shaft downstream. However, in an erosive service the
valve should be installed with the shaft upstream. With
the shaft upstream, erosive action will occur in the
retainer and not the ball surface or the valve body. To
determine the seating/breakout torque, use equation
(16.108) or (16.109), according to the application.
For shaft downstream, seating/breakout torque is
shown as:
Tbo = TP + TS + ∆Pmax (CB + Cs) + TH
(16.108)
For shaft upstream, seating/breakout torque is shown
as:
∆Pmax = Pressure drop (lb/in2) across the valve when
valve is in the closed position.
TD = Dynamic torque (in-lb) is the torque required
to overcome the torque on the closure member caused by the fluid-dynamic forces on the
ball.
∆Peff = Actual pressure drop (lb/in2) across the valve
at the flowing condition which occurs when
the valve is in an open position. ∆Peff is less
than or equal to ∆P(choked).
∆Pchoked = FL2(P1 - FfPV)
(16.111)
Where: FL = Valve recovery coefficient
(See Table 16-XXXIV)
P1 = Upstream pressure, psia
Ff = Liquid critical pressure ratio
Pv = Vapor pressure of liquid, psia
CB = Bearing torque factor (in3). As the pressure
across the valve increases, the force on the
bearings increases proportionally.
CB(∆P) = bearing torque (in-lb).
(See Table 16-XXXVI)
Tbo = TP + TS + ∆Pmax (CB) + A + TH
(16.109)
NOTE: A = (TS - ∆P(CS). If A is less than zero, enter zero
for A.
In liquid service applications, the dynamic torque must
also be determined. Actuator sizing is based on the
seating/breakout torque and dynamic torque. To determine dynamic torque, use the following equation:
TD = TP + ∆Peff(CD + CB)
(16.110)
CS = Seat torque factor (in3). As the pressure
across the valve increases, the force at which
the seat pushes into the ball increases (shaft
downstream) or decreases (shaft upstream).
(See Table 16-XXXVI)
CD = Dynamic torque factor. (See Table 16XXXVI)
TH = Handwheel torque. TH = 0 without handwheel
(See Table 16-XXXII)
16-23
Table 16-XXXIV:
Approximate FL
Percent of
Rated CV
Approximate
FL
10
20
30
40
50
60
70
80
90
100
.90
.85
.82
.78
.73
.68
.65
.63
.62
.60
Table 16 - XXXV:
Valve/Actuator Compatibility - ShearStream
Actuator
Size
(in2)
Spring
Size
Valve/Actuator
Compatibility
Valve Size (inches)
1
STD. 25
STD.
STD. 25
STD. 50
H.D.
STD.
STD. 50
STD. 100
H.D.
STD.
STD. 100
STD. 200
H.D.
STD.
STD. 200
H.D.
1.5
2
3
4
6
8
10
12
Table 16-XXXVI: ShearStream Static Torques - Sizing
Valve
Size
TP=Packing Torque
(in-lb)
TS=Seat
Torque
CB=Bearing
Torque Factor
(in.)
(1)
(2)
(3)
(4)
(5)
(in-lb)
(6)
(7)
1
11/2
2
3
4
6
8
10
12
43
50
50
57
57
71
71
104
104
228
280
280
333
333
438
438
648
648
421
477
477
533
533
646
646
870
870
301
350
350
399
399
496
496
691
691
57
63
63
71
71
92
92
151
151
20
40
60
150
360
540
670
1100
1300
0.06
0.06
0.06
0.19
0.38
0.97
1.58
4.38
5.61
0.09
0.09
0.09
0.28
0.58
1.45
2.37
6.57
8.41
(1) TFE or filled TFE V-ring packing
(2) Grafoil
(3) Twin Grafoil
(4) Asbestos-free packing (AFP)
16-24
(5) Braided PTFE
(6) TFE lined bearings
(7) Metal bearings
CS=Seat
CD = Dynamic
Torque Factor Torque Factor
60O
0.1
0.1
0.15
0.42
0.82
1.64
2.62
4.55
6.05
90O
0.25
0.6
0.5
1.0
1.0
2.1
4.5
8.0
10.0
17.0
19.5
30.5
52.0
75.5
108.0 165.5
191.0 218.5