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Local regulations may restrict the use of this product to below the conditions quoted.In the interests of development and improvement of the product, we reserve the right to change the specification.

ISO 9001

Cert. No. LRQ 0963008

TI-GCH-27CH Issue 3

Superheated SteamSizing Chart

IntroductionTI-GCH-03 covers the sizing of steam control valve Kv values foruse with saturated steam. However, should the steam supply havea degree of superheat, allowance must be made for the associatedincrease in specific volume that occurs. The effect of an increasingdegree of superheat increases the desired Kv value.The chart shown overleaf applies a superheat correction factorwhen determining the required Kv of steam control valves.

How to use the chart

Example 1How to find the Kv value for a critical flow application:-

Steam demand 700 kg/h

Steam supply pressure upstream 2 bar gaugeof the valve 3 bar absolute

Steam condition 50C superheat

Pressure drop across valve Critical pressure drop

Refer to the selection chart opposite1. Follow the 700 kg/h steam flow line until it intersects with the

vertical 50C superheat line. At this intersection draw ahorizontal line.

2. Draw a horizontal line from 3 bar absolute to the critical pressuredrop line. At this point of intersection drop a vertical line.

3. At the crossing point of these 2 lines read off the Kv valuerequired, i.e. Kv is between 16 and 25.

4. Select the valve size required from the appropriate valve typeTechnical Information Sheet.

Example 2How to find the Kv value required for a non-critical flowapplication:-

Steam demand 100 kg/h

Steam supply pressure upstream 1 bar gaugeof the valve 2 bar absolute

Steam condition 150C superheat

Downstream steam supply pressure 0.6 bar gauge

required 1.6 bar absolutePressure drop across valve

2 bar a - 1.6 bar a 0.4 bar

Refer to the selection chart opposite1. Follow the 100 kg/h steam flow line until it intersects with the

vertical 150C superheat line. At this intersection draw ahorizontal line.

2. Draw a horizontal line from 2 bar absolute inlet pressure. At thepoint of intersection with 0.4 bar pressure drop, draw a verticalline downwards.

3. At the crossing point with the 100 kg/h horizontal line read offthe Kv value required, i.e. Kv = 6.3

4. Select the valve size required from the appropriate valve typeTechnical Information Sheet.

Note: This chart is for Examples 1 and 2 only.

A complete chart for sizing is shown overleaf.

0.8

1

2

3

4

5

8

10

20

30

40

50

80

10

20

30

40

50

80

100

200

300

400

500

800

1000

2 000

3 000

4 000

5 000

8 000

10 000

20 000

30 000

40 000

50 000

80 000

Inletpressurebara(absolute)

200 150 100 50 0

Criticalpressuredropline

0.1

0.2

0.3

0.5

0.4

1.6

2.5

4.0

6.3

25

16

63Kv=100

160

250

400

40

1.0Kv=

Kv=10

0.4

Pressured

ropbar

Example 1

Example 2

Steamflowkg/h(3600=kg/s)

Superheat C

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0.8

1

2

3

4

5

8

10

20

30

40

50

80

10

20

30

40

50

80

100

200

300

400

500

800

1000

2 000

3 000

4 000

5 000

8 000

10 000

20 000

30 00040 000

50 000

80 000

Inletpressurebara(absolute)

200 150 100 50 0

Criticalpressuredropline

0.10.2

0.30.5

1 2 3 5

10

20 30

Pressuredropbar

0.4

1.6

2.5

4.0

6.3

25

1.0

Kv=

Kv=10

16

63Kv=100160

250

400

40

Superheated Steam Sizing Chart TI-GCH-27CH Issue 3

Superheated steam sizing chartThe sizing chart is empirical and should not be used for critical applications

Stea

mflowkg/h(3600=kg/s)

Superheat C