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Control valve types

Valve types and typical flow parameters

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1. Globe valves
2. Angle valves
3. Butterfly Valves
4. Gate Valves
5. Ball Valves

This page is giving details about the design of the main valve types found in process industries for process control. For sizing the valves, please refer to the following pages :

1. Globe valves

What is a globe valve ?

Globe valves are among the most popular design for control valves as they allow usually a fine regulation that cannot be reached by butterfly valves, ball valves or gate valves. The flow in between the inlet and outlet of the valve is regulated thanks to a plug that can rest on a seat to close the valve or get lifted in order to allow the flow of fluid.

They are named globe valves because of the globular shape of the cavities within the valve body.

Globe valve drawing

Figure 1 : globe valve [Aimonen]

Globe valve drawing

Figure 2 : globe valve [Padleckas]

1. body
2. ports
3. seat
4. stem
5. disc or plug when valve is open
6. handle or handwheel when valve is open
7. bonnet
8. packing
9. gland nut
10. fluid flow when valve is open
11. position of disc if valve were shut
12. position of handle or handwheel if valve were shut


The plug, cage (see below), seat rings and seals are called the trim.

The drawings above represent the most popular type of globe valve. An alternative design exists where the plug is within a cage. Lifting the plug is releasing passageway for the product to flow.

Flow parameters of globe valves

The values below are given by [Emerson] and can be used in basic design to have a rough idea of the size of the valve to select :

Valve size (NPS) Valve plug type Flow characteristic Port diameter (in) Rated travel (in) Cv FL XT FD
1/2 Post-Guided Equal-Percentage 0.38 0.5 2.41 0.9 0.54 0.61
3/4 Post-Guided Equal-Percentage 0.56 0.5 5.92 0.84 0.61 0.61
1 Micro-Form Equal-Percentage 3/8 3/4 3.07 0.89 0.66 0.72
1 Micro-Form Equal-Percentage 1/2 3/4 4.91 0.93 0.8 0.67
1 Micro-Form Equal-Percentage 3/4 3/4 8.84 0.97 0.92 0.62
1 Cage guided Linear 1-5/16 3/4 20.6 0.84 0.64 0.34
1 Cage guided Equal-Percentage 1-5/16 3/4 17.2 0.88 0.67 0.38
1-1/2 Micro-Form Equal-Percentage 3/8 3/4 3.2 0.84 0.65 0.72
1-1/2 Micro-Form Equal-Percentage 1/2 3/4 5.18 0.91 0.71 0.67
1-1/2 Micro-Form Equal-Percentage 3/4 3/4 10.2 0.92 0.8 0.62
1-1/2 Cage guided Linear 1-7/8 3/4 39.2 0.82 0.66 0.34
1-1/2 Cage guided Equal-Percentage 1-7/8 3/4 35.8 0.84 0.68 0.38
2 Cage guided Linear 2-5/16 1-1/8 72.9 0.77 0.64 0.33
2 Cage guided Equal-Percentage 2-5/16 1-1/8 59.7 0.85 0.69 0.31
3 Cage guided Linear 3-7/16 1-1/2 148 0.82 0.62 0.3
3 Cage guided Equal-Percentage 3-7/16 1-1/2 136 0.82 0.68 0.32
4 Cage guided Linear 4-3/8 2 236 0.82 0.69 0.28
4 Cage guided Equal-Percentage 4-3/8 2 224 0.82 0.72 0.28
6 Cage guided Linear 7 2 433 0.84 0.74 0.28
6 Cage guided Equal-Percentage 7 2 394 0.85 0.78 0.26
8 Cage guided Linear 8 3 846 0.87 0.81 0.31
8 Cage guided Equal-Percentage 8 3 818 0.86 0.81 0.26

2. Angle valves

What is an angle valve ?

An angle valve is a special design of globe valve. The inlet and outlet are however at 90°. This can be interesting to self drain the outlet of the valve.

3. Butterfly valves

What is a butterfly valve ?

Butterfly Valve
Figure 3 : Butterfly valve

Butterfly valves, compared to globe valves present the advantage to have a very low resistance to the fluid flow when opened, which means they can reach high Cv for relatively small sizes.

They however offer a less fine control of the flow during regulation.

Butterfly valves can be available without gasket, the sealing is then done metal / metal which means there is a leakage. The leakage is reduced or avoided when using a polymer gasket. The material for the gasket must be chosen according to the service of the valve.

Note that a it is possible to have the disc that is offset from the shaft centerline which allows to reduce friction and wear when moving the valve. Such design is called an eccentric butterfly valve or a high performance butterfly valve.

Butterfly valve

Figure 4 : eccentric butterfly valve

Flow parameters of butterfly valves

The values below are given by [Emerson] and can be used in basic design to have a rough idea of the size of the valve to select :

Valve size (NPS) Degree of opening Cv FL XT FD
2 60 58.9 0.76 0.5 0.49
2 90 80.2 0.71 0.44 0.7
3 60 115 0.81 0.46 0.49
3 90 237 0.64 0.28 0.7
4 60 270 0.69 0.32 0.49
4 90 499 0.53 0.19 0.7
6 60 664 0.66 0.33 0.49
6 90 1260 0.55 0.2 0.7
8 60 1160 0.66 0.31 0.49
8 90 2180 0.48 0.19 0.7
10 60 1670 0.66 0.38 0.49
10 90 3600 0.48 0.17 0.7
12 60 2500 '- '- 0.49
12 90 5400 '- '- 0.7
16 60 3870 0.69 0.4 '-
16 90 8600 0.52 0.23 '-

Alternatively, [Midoux] is giving the following general relations :

Cv/Dv2 = 5.10-2*f2
f=(90-θ)/90

and FL ~ 0.675

With

Dv = nominal diameter of the valve (m)
θ = degree of opening (degrees) - 90 degrees is closed
Cv is given in m3/s (possible to convert in gpm by multiplying this value by 1.32*106)

Example : 4 inch valve at 90 degrees opening.

f=1
Cv=5.10-2*(0.1016)2=5.16*10-4 m3/s
Cv=681 gpm
Fl = 0.675

This is quite in accordance with the table above (Cv = 499, FL=0.53)

4. Gate valves

What is a gate valve ?

Gate Valve

5. Ball valves

What is a ball valve ?

The name ball valve comes from the fact that the closing element has the shape of a ball. This ball has actually a hole that allows to let the fluid pass when open. When closed, the plain side of the ball faces the fluid and allows a rather tight seal.

Segmented ball valves or V-notch ball valves also exist.

Flow parameters of ball valves

The values below are given by [Emerson] for V-notch ball valves and can be used in basic design to have a rough idea of the size of the valve to select :


Valve size (NPS) Degree of opening Cv FL XT FD
1 60 15.6 0.86 0.53 '-
1 90 34 0.86 0.42 '-
1-1/2 60 28.5 0.85 0.5 '-
1-1/2 90 77.3 0.74 0.27 '-
2 60 59.2 0.81 0.53 '-
2 90 132 0.77 0.41 '-
3 60 120 0.8 0.5 0.92
3 90 321 0.74 0.3 0.99
4 60 195 0.8 0.52 0.92
4 90 596 0.62 0.22 0.99
6 60 340 0.8 0.52 0.91
6 90 1100 0.58 0.2 0.99
8 60 518 0.82 0.54 0.91
8 90 1820 0.54 0.18 0.99
10 60 1000 0.8 0.47 0.91
10 90 3000 0.56 0.19 0.99
12 60 1530 0.78 0.49 0.92
12 90 3980 0.63 0.25 0.99
16 60 2380 0.8 0.45 0.92
16 90 8270 0.37 0.13 1


Source


[Aimonen] Globe valve drawing on Wikipedia
[Padleckas] Globe valve drawing on Wikimedia Commons
[Emerson] Control Valve Handbook 5th edition, Emerson Fisher
[Midoux] Mecanique et Rheologie des Fluides, page 392, Midoux, Lavoisier