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6.2 Calculation formula for Cv value
<For liquid>
. 0
365
V
Cv
=
P
∆
<For steam>
P
P
When
>
2
2
Cv
=
138
P
P
≤
When
2
Wk
Cv =
120
Cv: Cv value of each nominal size
W: Max. steam flow rate [kg/h]
Q: Max. gas flow rate [m
V: Max. liquid flow rate [m
P
: Inlet pressure [MPa∙A]
1
P
: Outlet pressure [MPa∙A]
2
Cv value
7.1 Precaution for installation
Electric wiring work must be performed by a professional.
1. When there is a risk of having life hazard, harming a body or property by the malfunction of the
product, please install the safety device which operates interception, opening, warnings according
to each facility.
2. The product cannot be used as an emergency shutoff valve.
* The product is not designed as a safety valve such as an emergency shutoff valve. If the product
is applied to a system that needs safety measures, install other equipment besides the product to
ensure the safety.
3. The product is not explosion-proof. Do not use it in the area or ambience where explosive gases
accumulate.
* Doing so may cause fire.
4. Connect the cables only after confirming that no power is supplied.
* Failure to do so may cause an electric shock.
5. Connect the cables according to the instruction after confirming the rated voltage.
* Erroneous cable connection may cause an electric shock or fire.
6. Do not supply electric power to the coil while it is detached from the valve.
* Doing so may result in coil burnout or fire due to an overcurrent.
G
1
Wk
P
P (
P
)
∆
+
1
2
1
2
P
1
3
/h (standard condition)]
3
/h]
Model
DD-2
DD-3
DD-2-8
DD-3-8
DD-3-8N
<For air>
P
When
Cv
P
When
Cv
=
∆P: P
– P
1
K: 1 + 0.0013 × {superheated steam temp.[˚C]
G: Specific gravity (for gas, relative to air
/for liquid, relative to water)
Cv value
1.7
0.55
7. Installation
Warning
6
P
1
>
2
2
Q
(
273
) t
G
+
=
2940
P
P (
P
∆
+
1
P
1
≤
2
2
Q
(
273
) t
G
+
2550
P
1
[MPa]
2
– saturated steam temp. [˚C]}
)
2
■EPDT-251b■
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