Masoneilan VariPak Adjustable Cv Control Valves Instruction Manual
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2. Operation
The Masoneilan VariPak microflow control valve
features a very wide range of rated flow coefficients
(Cv), from 0.004 to 3.8.
Two types of actuators are available:
- The VariPak 28001 with a single lever, designed for
just one rated Cv. This version is used when enough is
known about the operating conditions when sizing the
valve.
- The VariPak 28002 with an adjustable rated Cv. This
valve uses a patented lever system to adjust the rated
Cv on site to suit the actual operating conditions,
thereby avoiding any oversizing in flow capacity.
Each plug and seat ring combination can be adjusted
without changing the control signal.
2.1 PRECISE ADJUSTMENT OF THE VARIPAK 28002
ADJUSTABLE-Cv VALVE
The valve is adjusted using a simple, but robust,
crossed-lever system with an adjustable fulcrum. This
can be done easily by hand, either before installation or
during operation. For example, an application requiring
a theoretical Cv of 0.006 could be handled using a
VariPak 28002 with a maximum Cv of 0.010, that can
subsequently be calibrated on site between 0.004 and
0.010.
2.2 FLOW COEFFICIENT OF VARIPAK 28001
SINGLE-LEVER AND 28002 ADJUSTABLE-Cv
VALVES
2.2.1 Plug/seat ring combinations (trim)
Eight plugs and five seat rings are used to
make up the ten available plug and seat ring
combinations, identified by codes from 0 to 9
(see figure 2). The shape of each plug and the
port diameter of the seat ring can be used to
match parts with the table in figure 2.
The difference between the four plugs in trim
Nos. 6 to 9 lies in the angle of the flat machined
on the tip. The same seat ring (3e) and the
same spacer (3f) are used in all four cases (see
figure 2).
Use the table in figure 1 to select the plug and
seat ring combination to obtain the Cv value or
range of Cv values you require.
Trim No.
FLOW COEFFICIENT Cv
VARIPAK
28001
VARIPAK 28002
MIN.
RISK FREE
MAX.
9
0.0040
0.0016
0.0020
0.0024
0.0028
0.0032
0.0036
0.0040
8
0.010
0.004
0.005
0.006
0.007
0.008
0.009
0.010
7
0.025
0.010
0.013
0.016
0.019
0.021
0.023
0.025
6
0.050
0.020
0.025
0.030
0.035
0.040
0.045
0.050
5
0.10
0.04
0.05
0.06
0.07
0.08
0.09
0.10
4
0.25
0.10
0.13
0.16
0.19
0.21
0.23
0.25
3
0.6
0.25
0.30
0.35
0.4
0.45
0.5
0.55
0.6
2
1.2
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1
2.3
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
0
3.8
1.5
1.9
2.3
2.6
2.9
3.2
3.5
3.8
Figure 1
