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2. Nominal size selection
The appropriate nominal size can be calculated by obtaining the Cv value for the
operating conditions in question, as shown below.
【In case of steam application】
P
＞
1
P
2
2
Cv
Δ
138
：Inlet press.(MPa･A)
P
1
：Reduced press.(MPa･A)
P
2
k：1+0.0013×｛Super-heated temp. (℃)－ Saturated heat temp. (℃)｝
Cv：Cv value depend on each size
【In case of air application】
P
＞
1
P
2
2
Q
Cv
2940
：Inlet press.(MPa･A)
P
1
：Reduced press.(MPa･A)
P
2
ΔP：P1－P2(MPa)
Cv：Cv value depend on each size
【In case of liquid】
V：Max. liquid flow rate (m
ΔP：P1－P2(MPa)
Cv：Cv value depend on each size
Rated Cv value
Size
Rated Cv value
Caution
When selecting pipe size, please take piping condition and application into consideration
and secure a safety rate of 80 %
Wk
P
P (
P
)
1
2
(
273
) t
G
Δ
P
P (
P
)
1
2
Cv
15A
20A
6
9
P
Cv
W：Max. steam flow rate(kg/h)
－Ｐ
ΔP：Ｐ
1
P
Cv
Q：Max gas flow rate (m
condition)
t： Gas temperature(℃)
G：Specific gravity ( it is against air)
. 0
365
V
G
Δ
P
3
/h)
G:Specific gravity (It is against
water)
25A
32A
40A
14
25
33
-2-
P
≦
1
2
2
Wk
120
P
1
(MPa)
2
P
1
≦
2
2
Q
(
273
) t
G
2550
P
1
3
/h nominal
50A
65A
80A
50
85
106
■ EPDT-318a ■
100A
175
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