key design characteristics - powerflo · key design characteristics multiple-step axial flow high...

KEY DESIGN CHARACTERISTICS

MULTIPLE-STEP AXIAL FLOW HIGH RESISTANCE TRIM

78000 design is based on the principle of multi-step high resistance axial flow. Pressure reduction occurs along the

length of the plug through a series of throttling stages, designed to divide the total drop equally between the trim

elements or steps (assuming incompressible flow throughout), No individual stage is ever exposed to the full pressure

differential and as a result, trim life is greatly extended. In addition, the fluid takes a tortuous path. This adds

resistance and therefore velocity head loss.

LOW PRESSURE RECOVERY

The valve trim is designed to reduce pressure recovery (exhibits high C ); to lessen chances of vaporization at the

orifice; and consequently, eliminates cavitation for liquid service and contributes towards reduction of noise for all

fluids. When the plug is in the wide-open position, the fluid velocity is nearly constant through the trim. The tortuous

flow path adds significantly to the overall pressure losses. In the wide-open position, ideal conditions are approached:

that is, continuous pressure drop and no appreciable recovery. At this point, the C is practically equal to 1. At reduced

lift positions, the throttling mechanism is similar to a piping system with a number of single stage valves in series. Each

stage throttles a portion of the total pressure drop with an increase in velocity and subsequent pressure recovery.

Overall pressure recovery factor varies with the number of stages and please refer page 8 for the total Pressure

Recovery factor (C ) for each size.

TIGHT SHUT-OFF & SEAT PROTECTION

Protection against seat erosion is ensured by provision of ANSI/FCI 70.2 Class V seat shut-off when standard metal seats

are furnished. Pressure reduction is accomplished between the multi-step plug & the liner and not across the seat ring.

Thus in any severe service, seat ring damage due to high pressure drop can be ruled out.

SPECIAL SOFT SEAT DESIGN

Bubble tight leak tightness as per ANSI/FCI 70.2 Class VI can be achieved when optional soft seats are supplied. The

special seat ring with sliding collar shelters the resilient insert from the high-pressure fluid, when the valve opens.

HIGH-PERFORMANCE MATERIAL IS STANDARD

78000 series high pressure valves are manufactured from solid steel forgings to assure material integrity. Castings also

available as option. Without exception, the material specified as standard have been tested and selected to provide

trouble free operation in services with high pressures and erosive fluids. The high performance trim material

employed ensures durability of the valve for any severe application. Special trim material available for NACE and

corrosive application.

HIGH ALLOWABLE PRESSURE DROPS

With balanced trim design for sizes 2” through 6”, a wide range of allowable shut -off pressure drops is available with

conventional spring diaphragm actuators.

VARIETY OF BODY CONFIGURATION OFFERINGS

A standard angle body and optional in-line body styles are offered to accommodate a variety of piping requirements.

SIMPLE TRIM MAINTENANCE

The multiple step trim, made from specially chosen hard material gives maximum service life and the quick change

seat ring design provides ease of trim replacement.

LARGE FLOW AREA

Because of their relatively large flow passages and shearing action provided by the multiple stage plug & cage

designs, these valves are particularly well suited for applications involving fluids with entrained particles.

f

f

f

1

Leakage Class / Temperature Range(3)

Class IV : 0.01% of maximum rated capacity at 50 psig to atmosphereClass V : 5 x 10 ml/min of water per inch of orifice diameter per psi differentialClass VI: Bubble Tight as per ANSI/FCI 70.2

Special Designs available for applications outside the given temperature range, consult MIL

4

(3) :

Valve Size(Inch)

2 through 6

TypeTemperature Range

(Deg.C)

UnbalancedMetal Seat

BalancedMetal Seat

Soft Seat

-29

-29

-29

260

232

204

IV

IV

V

V

VI

Seat Leakage Class(As per ANSI/FCI 70.2)

1 through 6

1 through 6

PRESSURE DROP DIAGRAM OF A CONVENTIONAL VALVEIN CAVITATING SERVICE

(Pressure drops below the vapour pressure at thevena-contracta and then recovers, resulting in cavitation.

P1

P2

PV

78000 PLUG AT FULL OPEN POSITION(Continuous pressure drop & no appreciable recovery)

P1

P2

PV

3

Detail of thePTFE Soft-Seat Ring

PTFEInsert

78000 SERIES UNBALANCED PLUG CONSTRUCTION

Metal Seat

20

18

16

1512

1917

1

13

8

5

4

2

3

6

710

11

9

4

Material of construction(4)

(4): For other material consult MIL: Refer page 6, For sizes 2" through 6" only: Refer page 6, For balanced construction only, sizes 2" through 6"

(5)

(6)

Alloy Steel ASTM A 182 Gr. F11 / F22

St. Steel 17.4 PH ASTM A 564 Gr 630, Cond H 1075

Alloy Steel ASTM A 193 Gr. B7

St. Steel ASTM A 194 Gr. 8

Carbon Steel ASTM A 105

St. Steel ASTM A 479 Ty 304


PTFE


Stainless Steel ASTM A 182 Gr. F316


Alloy Steel ASTM A 194 Gr 2H

SS 304 + Asbestos or Graphite (spiral wound)

ASTM A 276 Ty. 420 (Roll Pin), SS 316 (Plug Pin)

Drawing

Ref. No.

Part Name Standard Material

1

2

3

4

5

6

7

8,18

8BS

8BF

9

10

11

12,13

14

15

16

17

19

20

Valve Plug Stem

Packing Flange Stud

Packing Flange Nut

Packing Flange

Packing Follower

Packing Spacer/Lantern Ring

Gland Packing

Bonnet, Body

Carbon Steel ASTM A 105Bonnet Flange(5)

Carbon Steel ASTM A 106 Gr. BBonnet Spacer(5)

Body Stud

Body Nut

Body Gasket

Roll Pin, Plug Pin

Balancing Seal Set(6)

Plug

Seat Ring

Seat Ring Gasket

<180 C0

GRAPHITE>180 C0

Spring energised Carbon Filled PTFE

Liner St. Steel 17.4 PH ASTM A 564 Gr 630, Cond H 1075

Spacer St. Steel 17.4 PH ASTM A 564 Gr 630, Cond H 1075

St. Steel 440 C ASTM A 276 Ty 440C, Hardened

St. Steel ASTM A 479 Ty 316+ Stellite No. 6 or PTFE


< 232 C0

5

78000 SERIES BALANCED PLUG CONSTRUCTION

18

16

15

12

1917

1

13

8

8BS

8BF

5

4

2

3

6

7

10

14

9

6

Optional Material for Corrosive Service(4)

Inconel X 750 ASTM A 461 (HRC 35 max.)


St. Steel ASTM A 194 Gr. 8






Stainless Steel ASTM A 182 Gr. F316 (HRC 22 max.)


Alloy Steel ASTM A 194 Gr 2H


ASTM A 479 Ty 316

Spring energised Carbon filled PTFE

Drawing

Ref. No.

Part Name Standard Material

1 Valve Plug Stem

Packing Flange Stud

Packing Flange Nut

Packing Flange

Packing Follower

Packing Spacer/Lantern Ring

Bonnet, Body

Bonnet Flange(5)

Carbon Steel ASTM A 106 Gr. BBonnet Spacer(5)

Body Stud

Body Nut

Body Gasket

Roll Pin, Plug Pin

Balancing Seal Set(6)

Liner

Spacer

Plug

Seat Ring

Seat Ring Gasket

PTFE

GRAPHITEGland Packing

Ferralium 255, ASTM A 351 Gr. CD4MCU or

Ferralium 255, ASTM A 351 Gr. CD4MCU or

Inconel X 750 (HRC 35 max.)

Inconel X 750 (HRC 35 max.)

Nitronic 60, ASTM A479 Type S21800 with

HF on seat & guide area (HRC 35 max.)

St. Steel ASTM A 479 Ty 316+ Stellite No. 6 or PTFE


Monel K500 or

Monel K500 or

Nitronic 50, ASTM A479 Type XM19 withHard facing on seat area or

(4): For other material consult MIL, Certification to NACE MR01-75, Latest revision available(5)

(6)

: Refer page 6, For sizes 2" through 6" only: Refer page 6, For balanced construction only, sizes 2" through 6"

2

3

4

5

6

7

8,18

8BS

8BF

9

10

11

12,13

14

15

16

17

19

20

<232 C0

7

0

100

0 100

Flow Coefficients - Rated Cv, Critical Flow Factor - Cf

ValveSize &Rating

Travel(Inch)

MinimumOperable

Cv

Liquid Gas orSteam

OrificeDia

(Inch)

Trim Type

Cf Cf Cf CfCv Cv Cv Cv

A B B+

0.500

1.00

1.875

3.250

3.250

3.250

3.250

0.6 0.9850.992

0.991

0.991

0.988

0.988

0.988

0.9, 1.1 - 0.750.970

3.6, 4.5

12, 15

40, 55, 70*

40, 55, 70*

70, 110

55

0.982 0.970 3.5

13

40

40

60

40

0.970

0.970

0.970

0.970

0.970

0.982

0.978

0.978

0.978

0.978

2.4

8

30

30

30

0.03

0.06

0.12

0.61

0.61

1.5

0.61

0.125 0.998

0.997

0.997

0.997

0.997

- - - -

0.997

0.25

0.50

0.88

0.88

0.88

0.88

0.1, 0.3

1.2

4

15

15

15

1" 2500#<

1.5" 2500#<

2" 2500#<

3" 2500#<

4" 2500#<

6" 600#<

6" 900#>

8

* Cv-70 with cast body upto ANSI Class 600#

Trim Characteristic

78000 series valves have an inherent Mod. Linear characteristic, integrating the clearance flow concept over 10% of the initialvalve travel to avoid high pressure drops in the seating area and throttling at low lifts. The 10 to 100% of the travel ensuresprecise control.

Actuator Selection for 78000 series unbalanced valves

ValveSize

Stroke(inch)

Act.Size

Air to Open (38)

SpringRangePsig

SupplyPress.Psig

Shut off Pressure

Kg/cm2

SpringRangePsig

Shut off Pressure

Kg/cm2

1

1.5

Max.RatingANSI

Air to Close (37)

V VVI VI

250025 210 210 210 21012-16

18-22

14-20

24-30

16-25

23-33

15-25

18-30

15-25

18-30

15-25

18-30

420 420 420 420

210 210 175 175

420 420 316 316

70 70 35 35

140 140 60 60

28 28 17 14

70 63 28 21

28 28 17 14

70 63 28 21

28 28 17 14

70 63 28 21

30

30

50

40

60

30

60

30

60

30

60

2500

2500

2500

2500

2500

0.125

0.25

0.5

0.88

0.88

0.88

13

15

15

18

18

18

6-10

6-10

6-12

6-12

6-16

6-16

3-15

3-15

3-15

3-15

3-15

3-15

Actuator Selection for 78000 series balanced valves

ValveSize

Stroke(inch)

Act.Size

Air to Open (38)

SpringRangePsig

SupplyPress.Psig

Shut off Pressure

Kg/cm2

SpringRangePsig

Shut off Pressure

Kg/cm2

2

3

Max.RatingANSI

Air to Close (37)

V VVI VI

250035 210 210 210 21016-25

23-33

15-25

15-25

15-25

18-29

18-29

18-29

420 420 386 344

210

210

210

210

210

210

140 77

77

77

420

420

420

330

330

330

228

228

228

109

109

109

140

140

45

50

50

50

60

60

60

2500

2500

2500

0.5

0.88

0.88

0.88

15

18

18

18

6-16

6-16

3-15

3-15

3-15

3-15

3-15

3-15

2

3

4

6

4

6

9

Dimensions (mm)

10

VALVEANGLE VALVE INLINE VALVE

BUTT & SOCKET WELDBUTT WELD

A A AB B BH H H

SOCKET WELDSIZE(inch)

1 95

119

165

225

165

220

205

104

119

178

235

178

226

271

179

217

283

375

283

336

376

65

80

100

150

-

-

-

101.5

117

163

216

-

-

-

179

217

283

375

-

-

-

220

300

394

394

430

610

575

58

51

71

71

71

108

91

183

223

259

259

298

417

427

1.5

2

3

4X2

4X3

6X3

B

H

A

50

0(m

in)

B

H

A

50

0(m

in)

A

BH

50

0(m

in)

A

BH

50

0(m

in)

All dimensions in mm

Face to Face dimension tolerance 2mm+

Approximate dimensions of 78000 series Forged Valves, 2500#ANSI

Body

Bonnet

Trim

Type

Type

A(Liquid)

B+(Liquid)

B(Liquid)

Gas or Steam

Special

Yes

Yes

No

No

Type

Type

Type

Plug

Seat Ring

Type

Angle

Rating

Connection

Material

Material

Material

Material

Guiding

Size Refer Page 8

Refer Page 8

Flanged Butt-Weld Socket-Weld

Inline

Refer Page 5,7

Refer Page 5,7

Refer Page 5,7

Refer Page 5,7

Refer Page 2

Refer Page 9

Refer Page 9

Close Open Stayput

Refer Page 5,7

Unbalanced

Clamped

Liner

Balanced

Standard

Lubricator

Packing

Liner&Spacer

Flow Direction Flow to Open

IV V VI

Model Number

Leakage Class(ANSI/FCI 70.2)

Air to Open Air to Close

With Bellow Seal

Hand Wheel

Action

Air Failure

Actuator Size

Actuator

Actuator Spring Range

Accessories & Special Requirements

Pneumatic Spring Diaphragm

Piston Cylinder Manual

Electrical

FLUID PHASE

Required Parameters

LiquidSteam

Flow Rate (Start-up/Min/Nor/Max)

Inlet Press. (Start-up/Min/Nor/Max)

Outlet Press. Start-up/Min/Nor/Max)

Shut-off Pressure

Temperature

Specific Gravity or Density or Mol. Wt.

Vapour Pressure

Critical Pressure

Viscosity

Compressibility Factor

Specific Heat Ratio

Inlet & Outlet Pipe Size/Schedule

GasTwo-Phase

Liquid Gas Steam

Specification Data

Checklist below contains the necessary data to specify the basic 78000 series control valve. The pagereference will guide you to the appropriate sections when a selection is to be made. For accessoriesand special options, consult your MIL representative

Application Data

Checklist below provides a convenient means for listing all the process data required to properly size your 78000series control valve.

11

Working Temp

0F

100 38 20

ANSI 150#

WC9 WC9 WC9 WC9 WC9 WC9CF8M CF8M CF8M CF8M CF8M CF8M

ANSI 300# ANSI 600# ANSI 900# ANSI 1500# ANSI 2500#

19 53 51 105 101 158 152 264 253 440 422

363440

328427

301414

280390

264354

260345

255333

250312

248297

286 245

263 243

221 226

153

102

205

201

264 218

256 197

248 181

234 168

213 159

207 156

200 153

187 150

179 148

171 147

158 146

133 136

92

62

123

121

158 131

154 118

149 108

140 101

128 95

124 94

120 92

112 90

107 89

103 88

95 88

79 82

55

37

74

72

105 87

102 79

99 72

94 67

85 63

83 63

80 61

75 60

71 59

69 59

63 58

53 55

37

25

49

48

53 44

51 39

50 36

47 34

43 32

41 31

40 30

37 30

36 30

3034

2932

2726

18

12

25

24

18 17

16 15

14 14

12 12

10 10

9 9

8 8

7 7

6 6

5 5

4 4

2 2

1

1

1

1

93

149

204

260

316

343

371

399

427

454

482

510

537

565

200

300

400

500

600

650

700

750

800

850

900

950

1000

1050

0C

Max. Working Pressure in Kg./ cm2

Working Temp

0F

100 38 20

ANSI 150#

WCC WCC WCC WCC WCC WCCWC6 WC6 WC6 WC6 WC6 WC6

ANSI 300# ANSI 600# ANSI 900# ANSI 1500# ANSI 2500#

20 53 53 105 105 158 158 264 264 440 440

440 440

427 427

414 414

390 390

354 354

345 345

333 333

295 312

241 297

157 263

101 187

60 127

30 30

264 264

256 254

248 244

234 234

213 213

207 207

200 200

177 187

145 179

94 171

60 158

36 112

18 76

158 158

154 152

149 146

140 140

128 128

124 124

120 120

106 112

87 107

57 103

36 95

22 67

11 46

105 105

102 102

99 97

94 94

85 85

83 83

80 80

71 75

58 71

38 69

24 63

14 45

7 30

53 53

51 51

50 49

47 47

43 43

41 41

40 40

36 37

29 36

19 34

12 32

7 23

4 15

18 18

16 16

14 14

12 12

10 10

9 9

8 8

7 7

6 6

5 5

4 4

2 2

1 1

93

149

204

260

316

343

371

399

427

454

482

510

537

200

300

400

500

600

650

700

750

800

850

900

950

1000

0C

Max. Working Pressure in Kg. /cm2

Other useful information

Maximum working pressure for standard material (as per ASME B 16.34 - 1996)

FUNDAMENTAL DEFINITIONS

FLOW COEFFICIENT (Cv): Cv, which is universally accepted as a yardstick of control valve capacity is defined as thenumber of US gallons per minute of water at 60F that will pass through a given flow restriction with a pressure drop of1 psi. For example, a control valve, which has a maximum Cv of 16, has an effective full port area which allows flow of16 gallons per minute of water with 1 psi pressure drop.

CRITICAL FLOW FACTOR (Cf): Cf is a dimensionless expression of the pressurerecovery ratio in a control valve. As the fluid flows through a valve orifice, there isa marked increase in velocity. Increase in velocity is accompanied by a decrease inpressure. Velocity reaches a maximum and pressure it's minimum at the smallestcross-sectional flow stream area downstream of the orifice (vena contracta).Downstream to the vena contracta, the fluid decelerates and consequently thepressure recovers, hence the term pressure recovery.

P1: Valve Upstream PressureCf= P1- P2 P2: Downstream Pressure

P1-Pvc Pvc: Vena Contracta Pressure

PRESSURE

VELOCITY

VE

LO

CIT

Y&

PR

ESSU

RE

P2P1

VENA CONTRACTA

12

key design characteristics - powerflo · key design characteristics multiple-step axial flow high...

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