Datasheet

Series VX21/22/23
Solenoid Valve Flow-rate Characteristics 3
(How to indicate flow-rate characteristics)
Conversion of flow coefficient:
Av = 28 x 10
−6
Kv = 24 x 10
−6
Cv
……………………………………………
(11)
Here,
Kv factor : Value of the clean water flow rate represented by m
3
/h which runs through a
valve at 5 to 40°C, when the pressure differential is 1 bar.
Cv factor (Reference values): Value of the clean water flow rate represented by US gal/min which runs
through a valve at 60°F, when the pressure differential is 1 lbf/in
2
(psi).
Value is different from Kv and Cv factors for pneumatic purpose due to different test method.
Example 1)
Obtain the pressure differential when water 15 [L/min] runs through a solenoid valve with an
Av = 45 x 10
−6
[m
2
].
Since Q0 = 15/45 = 0.33 [L/min], according to Graph (2), if reading ΔP when Q0 is 0.33, it will be 0.031 [MPa].
Example 2)
Obtain the saturated steam flow rate when P1 = 0.8 [MPa], ΔP = 0.008 [MPa] with a solenoid valve with an
Av = 1.5 x 10
−6
[m
2
].
According to Graph (2), if reading Q0 when P1 is 0.8 and ΔP is 0.008, it is 0.7 [kg/h]. Therefore, the flow rate
Q = 0.7 x 1.5 = 1.05 [kg/h].
(4) Test method
Attach a test equipment with the test circuit shown in Fig. (3). Next, pour water at 5 to 40°C, then measure the
flow rate with a pressure differential of 0.075 MPa. However, the pressure differential needs to be set with a
large enough difference so that the Reynolds number does not go below a range of 4 x 10
4
.
By substituting the measurement results for formula (8) to figure out Av.
Fig. (3) Test circuit based on IEC60534-2-3, JIS B 2005
Test range
Equipment
for test
Thermometer
Restrictor
on the
upstream side
Restrictor on the
downstream side
Flow
meter
Pressure
tap
2
d
≥ 20d ≥ 10d
6d
Pressure
tap
Water flow rate Q0 [L/min] when Av = 1 x 10
−6
[m
2
])
Saturated steam flow rate Q0 [kg/h] (when Av = 1 x 10
−6
[m
2
])
Pressure differential ΔP [MPa]
Upstream pressure
P1 = 1 MPa
P1 = 0.8 MPa
P1 = 0.6 MPa
P1 = 0.5 MPa
P1 = 0.1 MPa
P1 = 0.2 MPa
P1 = 0.4MPa
Example 2
Example 1
Graph (2) Flow-rate characteristics
3
2
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
3
2
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.001
0.040.030.02
0.01
0.0040.0030.002
0.1
P1 = 0.3 MPa
34