Bronkhorst Mass Flow - Manual (Page 25)

BRONKHORST HIGH-TECH B.V.
On LFC's only one type of normally closed valve is available. Diameter of orifice can be calculated or looked
up in the table.
Diameter [mm] K
v
Normally closed
∆ p max. [bard]
0,10
0,14
0,20
0,30
0,37
0,50
0,70
1,00
1,73 x 10 -4
3,39 x 10 -4
6,93 x 10 -4
1,56 x 10 -3
2,37 x 10 -3
4,33 x 10 -3
8,48 x 10 -3
1,73 x 10 -2
10
10
10
10
10
10
10
10
* For liquids having a dynamic viscosity: 15 cP < µ < 100 cP the K
v
value should be calculated according to:
K
p v v
=
⋅
⋅ Φ
∆
ρ
µ
1000
Units:
Φ
v
= volume flow [m 3 /h]
ρ = density at 20°C and 1 atm. [kg/m 3 ]
∆ p = delta p [bard]
µ = dynamic viscosity [c
p
]
For maximum possible viscosity apply to factory
4.8 Maximum pressure drop
For (pilot) solenoid operated control valves with small orifices the maximum allowable pressure drop for
gases is according to the table.
Diameter [mm] K
v
Normally closed
∆ p max. [bard]
Normally opened
∆ p max. [bard]
0,05
0,07
0,10
0,14
0,20
0,30
0,37
0,50
0,70
1,00
1,30
1,50
1,70
2,00
4,33 x 10 -5
8,48 x 10 -5
1,73 x 10 -4
3,39 x 10 -4
6,93 x 10 -4
1,56 x 10 -3
2,37 x 10 -3
4,33 x 10 -3
8,48 x 10 -3
1,73 x 10 -2
2,93 x 10 -2
3,90 x 10 -2
5,00 x 10 -2
6,63 x 10 -2
40
30
30
30
30
30
30
30
24
12
8
6
5
3.6
30
20
20
20
20
20
20
20
15
8
5
n.a.
n.a.
n.a.
For pilot operated valves the maximum pressure drop is limited to 20 bard. If the pressure drop during start-
up is higher, it is preferred to install a bypass valve. During start-up this valve should be opened. Also the
minimum pressure drop is limited. For exact figures consult factory or proceed according to the technical
data and/or additional instructions given by the sales office or department.
9.17.001 page 25