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5.4 Nominal size selection
5.4.1 Nominal size selection chart
Determination of nominal size when the inlet pressure is in a range 2.5 kPa to
200 kPa (fluid: air, at 20 ℃ )
E xample
《
》
Select the nominal size of a pressure reducing valve to be operated with the inlet pressure
10 kPa and reduced pressure 3 kPa at a flow rate 15 m
point (A) on the chart where the inlet pressure 10 kPa line and reduced pressure 3 kPa line
intercross. Draw a line from the intersection straight down to the point (B) where it meets the
line representing flow rate 15 m
size 20 A and 25 A. It is selected to use 25 A (larger one) as the desired nominal size.
Table 1 Determination of nominal size when inlet pressure in
the range 200 to 400 kPa
Nominal
size
15A
20A
25A
3
/h (normal condition). The point (B) locates between nominal
Inlet pressure （ k Pa ）
200-400 incl.
200-300 excl.
300-400 incl.
200-300 excl.
300-400 excl.
400
5
3
/h (normal condition): First locate the
Rated flow rate (Nm
Reduced pressure （ k Pa ）
0.5-4 excl.
4-20 incl.
60
60
90
90
90
120
120
120
120
150
120
190
3
/h)
■ E P D T - 1 7 9 c ■
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