Master Flo Choke Valve Design

Flow Trim (External Sliding Sleeve and Internal Cage):

The choke valve system is based on a fixed radially ported internal nozzle (flow nozzle) with an external sliding sleeve (flow ring). The sleeve overlaps the nozzle ports to vary the flow.

Shutoff is accomplished by an independent seating area upstream and remote from the throttling area. The choke incorporates a dead band area to isolate the seating from the flow area. This isolates the seat from the throttling surface.

Wear Performance:

The external sleeve choke configuration has proven to provide superior wear control over other choke trim styles.

The Master Flo choke controls high velocity flow jets during throttling by directing the flow upwards into the flow ring thereby containing the erosive energy within the flow trim. This phenomenon is due to the external flow ring internal nozzle design. This system is unique in protecting the valve body from high velocity fluid impingement.

The potential wear is contained to the replaceable flow trim components, and this in turn reduces the need for an outlet blast wear sleeve as commonly seen with other trim configurations.

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Flow Control:

The staged ports within the flow nozzle are positioned radially and orthogonal (one pair to the other) to prevent failure of flow nozzle due to erosive linking of throttling ports and to provide precise flow control.

The use of only two sets of ports in the flow nozzle provides a long stem travel thus ensuring precise flow control throughout the range.

The staged port system provides control from a Cv below 0.1 up to the valve's maximum. This high turn-down ratio and control eliminates the necessity of multiple trim sizes.

Micrometer Indicator Head:

Master Flo manually operated chokes are supplied with an indicator head having a micrometer calibration scale* that provides positive, repeatable valve position indication to 1/10 of a turn increments.  This, together with the inherent controllability of the Master Flo trim design, results in excellent throttling control. Micrometer Indicator Head

The indicator head has a square cross-section with a different calibration scale on each face.  This ensures that the valve position can be monitored in the desired units including Cv, bean size, millimeters, or the micrometer scale.

For P2 and larger chokes, the indicator head is supplied with a grease fitting to allow lubrication of the upper stem area.

*Micrometer scale is standard on P5 and smaller, and optional on P6 and larger.

Stem Lock Assembly:

Master Flo's optional stem lock for manually operated chokes allows the stem to be locked in 10 positions per turn of the handwheel.  This provides a large number of fixed valve positions between the closed and full open position.

Valve Model Locking Positions

P2
P25
P3
P35
P4

110
120
170
160
200

Seat Leakage:

Master Flo choke valves attain Class V or, optionally, Class VI shutoff per ANSI B16.104 1976 (FCI 70-2).  Seating integrity is maintained throughout the service life of the flow trim.

Flow Trim Construction/Retention:

Flow trim components are available in solid 17-4 PH stainless steel, or in Stellite, or Tungsten Carbide held in stainless steel carriers with interference fits.  No epoxies, brazing, or threaded fasteners are used to retain components in their carriers.

The flow nozzle and seat are retained in the valve body by use of a retaining sleeve that is compressed against the seat by the valve bonnet.  The retaining sleeve also protects the valve body cavity against erosion.  No special tooling is required for maintenance or service.

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Master Flo Sizing/Flow Test Data:

The choke sizing data is based on ISA S75.01 and verified by actual flow tests conducted on an in-house flow test loop per ISA S75.02.

Quality Assurance/Certification:

Master Flo Valve Inc. maintains an accredited quality program in accordance to ISO 9001-94 and API Q1.  Master Flo Valve Canada is registered for the manufacture of choke valves and is approved to manufacture products under license to API-6A and API-17D.

Master Flo Valve (UK) operates under Quality Management System to BS 5750 Part II / ISO 9002 accredited by Bureau Veritas.


Valve Sizes

Valve Model

Std. End Connection Sizes

Standard Trim

Maximum Pressure Rating

Maximum Turning Torque at 3,000 PSI

# Turns Close to Open

Cv Bean Size

PSI

kPa

ft-lb

Nm

P05

1", 2"

2.5

24

10,000

69 000

10

15

6

P1

1", 2"

10

48

6,000

41 000

35

46

6

P2

2", 3"

20

72

10,000

69 000

60

83

11

P25

2",2-1/2",3"

33

93

5,000

34 000

60

83

12

15,000 103 000 70 92 9
20,000 138 000 70 92 9

P3

3", 4"

50

116

6,000 41 000 45 62 17
10,000 69 000 45 62 17
15,000 103 000 70 92 13

P35

4", 6"

100

160

6,000

41 000

70

92

16

15,000 103 000

P4

4", 6"

160

198

6,000

41 000

96

130

20

10,000 69 000

P5

5", 6", 8"

250

240

6,000

41 000

81

110

22-1/2

10,000 69 000

P6

6", 8"

335

280

6,000

41 000

81

110

27

P8

8", 10"

700

450

6,000

41 000

96

130

33-1/2

Other sizes and pressure ratings are available upon approval by Master Flo's engineering department.

Master Flo sizing is available upon request to ensure accurate valve selection to meet your specific needs.



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