4
Know-how makes the difference
B-V-NOTCH-UK-02-2014 REV. C
An
Company
D
P
[Bar]
DN10FB
DN15RB
30
o
[M
3
/h]
DN10FB
DN15RB
60
O
[M
3
/h]
DN15FB
DN20RB
30
O
[M
3
/h]
DN15FB
DN20RB
60
O
[M
3
/h]
DN20FB
DN25RB
30
O
[M
3
/h]
DN20FB
DN25RB
60
O
[M
3
/h]
DN25FB
DN32RB
30
O
[M
3
/h]
DN32FB
DN40RB
30
O
[M
3
/h]
DN25FB
DN32RB
60
O
[M
3
/h]
DN40FB
DN50RB
30
O
[M
3
/h]
DN32FB
DN40RB
60
O
[M
3
/h]
DN40FB
DN50RB
60
O
[M
3
/h]
DN50FB
DN65RB
30
O
[M
3
/h]
DN65FB
DN80RB
30
O
[M
3
/h]
DN80FB
100RB
30
O
[M
3
/h]
DN50FB
DN65RB
60
O
[M
3
/h]
DN65FB
DN80RB
60
O
[M
3
/h]
DN80FB
100RB
60
O
[M
3
/h]
DN100F
30
O
[M
3
/h]
DN100F
60
O
[M
3
/h]
0,01
0,070
0,140
0,190
0,370
0,380
0,770
0,830
1,110
1,300
1,450
2,210
3,400
3,660
5,270
5,530
7,060
8,760 10,880 11,050 18,020
0,02
0,099
0,198
0,269
0,523
0,537
1,089
1,174
1,570
1,838
2,051
3,125
4,808
5,176
7,453
7,821
9,984 12,389 15,387 15,627 25,484
0,03
0,121
0,242
0,329
0,641
0,658
1,334
1,438
1,923
2,252
2,511
3,828
5,889
6,339
9,128
9,578 12,228 15,173 18,845 19,139 31,212
0,04
0,140
0,280
0,380
0,740
0,760
1,540
1,660
2,220
2,600
2,900
4,420
6,800
7,320 10,540 11,060 14,120 17,520 21,760 22,100 36,040
0,05
0,157
0,313
0,425
0,827
0,850
1,722
1,856
2,482
2,907
3,242
4,942
7,603
8,184 11,784 12,365 15,787 19,588 24,328 24,709 40,294
0,06
0,171
0,343
0,465
0,906
0,931
1,886
2,033
2,719
3,184
3,552
5,413
8,328
8,965 12,909 13,546 17,293 21,458 26,650 27,067 44,140
0,07
0,185
0,370
0,503
0,979
1,005
2,037
2,196
2,937
3,439
3,836
5,847
8,996
9,683 13,943 14,631 18,679 23,177 28,786 29,236 47,676
0,08
0,198
0,396
0,537
1,047
1,075
2,178
2,348
3,140
3,677
4,101
6,251
9,617 10,352 14,906 15,641 19,969 24,777 30,773 31,254 50,968
0,09
0,210
0,420
0,570
1,110
1,140
2,310
2,490
3,330
3,900
4,350
6,630 10,200 10,980 15,810 16,590 21,180 26,280 32,640 33,150 54,060
0,10
0,221
0,443
0,601
1,170
1,202
2,435
2,625
3,510
4,111
4,585
6,989 10,752 11,574 16,665 17,487 22,326 27,702 34,406 34,943 56,984
0,20
0,313
0,626
0,850
1,655
1,699
3,444
3,712
4,964
5,814
6,485
9,883 15,205 16,368 23,568 24,731 31,573 39,176 48,657 49,417 80,588
0,30
0,383
0,767
1,041
2,027
2,081
4,217
4,546
6,080
7,120
7,942 12,105 18,623 20,047 28,865 30,289 38,669 47,980 59,592 60,523 98,700
0,40
0,443
0,885
1,202
2,340
2,403
4,870
5,249
7,020
8,222
9,171 13,977 21,503 23,148 33,330 34,975 44,651 55,403 68,811 69,886 113,968
0,50
0,495
0,990
1,344
2,616
2,687
5,445
5,869
7,849
9,192 10,253 15,627 24,042 25,880 37,265 39,103 49,922 61,943 76,933 78,135 127,421
0,60
0,542
1,084
1,472
2,866
2,943
5,964
6,429
8,598 10,070 11,232 17,119 26,336 28,350 40,821 42,835 54,687 67,855 84,276 85,593 139,582
0,70
0,586
1,171
1,590
3,096
3,179
6,442
6,944
9,287 10,877 12,132 18,490 28,446 30,622 44,092 46,267 59,068 73,291 91,029 92,451 150,766
0,80
0,626
1,252
1,699
3,309
3,399
6,887
7,424
9,928 11,628 12,969 19,767 30,411 32,736 47,136 49,462 63,147 78,352 97,314 98,834 161,176
0,90
0,664
1,328
1,802
3,510
3,605
7,305
7,874 10,530 12,333 13,756 20,966 32,255 34,722 49,996 52,462 66,977 83,105 103,217 104,830 170,953
1,00
0,700
1,400
1,900
3,700
3,800
7,700
8,300 11,100 13,000 14,500 22,100 34,000 36,600 52,700 55,300 70,600 87,600 108,800 110,500 180,200
2,00
0,990
1,980
2,687
5,233
5,374 10,889 11,738 15,698 18,385 20,506 31,254 48,083 51,760 74,529 78,206 99,843 123,885 153,866 156,271 254,841
3,00
1,212
2,425
3,291
6,409
6,582 13,337 14,376 19,226 22,517 25,115 38,278 58,890 63,393 91,279 95,782 122,283 151,728 188,447 191,392 312,116
4,00
1,400
2,800
3,800
7,400
7,600 15,400 16,600 22,200 26,000 29,000 44,200 68,000 73,200 105,400 110,600 141,200 175,200 217,600 221,000 360,400
5,00
1,565
3,130
4,249
8,273
8,497 17,218 18,559 24,820 29,069 32,423 49,417 76,026 81,840 117,841 123,655 157,866 195,880 243,284 247,086 402,939
V-NOTCH SIZE SELECTION GUIDE - LIQUID
FLOW VALUES AT 90% OPEN VALVE
Flow values for liquids are based on following:
Water, 20
o
C, density = 1kg/dm
3
Valve is
90%
OPEN (
90-100% OPEN = 20-30% additional flow capacity
)
Step 1:
Choose the differential pressure from left column.
Step 2:
Choose the flowrate value, equal to or just above the required.
Step 3:
Choose the valve Size and V-notch from top row.
Choosing the correct size V-notch will give you the best possible
regulation and maximum lifetime of valve.
Due to velocity and noise, DVC does not advice a higher differential pressure
than 5bar maximum for regulation. Max
D
P is 15bar (Fluid, not critical flow).
Constantly regulating at 15-25% OPEN valve will
reduce lifetime of valve seats.
Other valve sizes (6”) and V-notch (90
o
) on request.
V-NOTCH BALL- SIZING - LIQUID
0% (CLOSED)
50% (OPEN)
100% (OPEN)
PREFERRED SPAN
15% (OPEN)
90% (OPEN)
OPTIMUM SPAN
25% (OPEN)
Hysteresis and repeatability
Despite the fact that a V-notch control valve normal-
ly solves most common regulating tasks, there are
some mechanical limits in the hysteresis and repeat-
ability.
Slug between ball-stem, stem-coupling and coupling-
actuator causes the line of rotation to flex.
The overall hysteresis on a standard assembly can
amount up to 5% of flow.
To obtain a more accurate hysteresis, DVC is able to
offer our so called
Zero Backlash Coupling
which
eliminates the slug between stem-coupling and cou-
pling-actuator. The ZB-Coupling is able to expand in-
side the actuator outtake and clamp around the valve
stem. This eliminates almost any slug in the line of
rotation. The hysteresis with a ZB-coupling can be
guaranteed within a maximum of 2% totally.
Regulating in practice
For standard regulating tasks, the hysteresis
means that the up-scale and down-scale loads are
a bit different at the same output signal. However
the controller will keep adjusting to meet the re-
quired set point at all time. Settling time
*
however
will be a bit longer than valves with no slug.
*Settling time is the time it takes before the process is
stable, after a fluctuation in process value. The settling
time depends on a number of parameters such as control-
ler set point “P-I-D”, positioner, process variations etc.
Q2
Q1
STROKE
60% 100%
FLOW
Eq%
∆
Q - Hysteresis 5%
Q2
Q1
Stroke
∆
Q - Hysteresis 2%
60% 100%
FLOW
Eq%
15%
