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Flowseal
Metal Seat Valves - Cv Values Chart
Cv (Coefficients
of Volume) is the number of U.S. gallons per minute of water required
to pass through a valve with a pressure drop of 1 psi.
The chart
below records this Cv factor for the Flowseal valve classes and
sizes at ten degree increments between open and closed. The values
shown are for the valve installed in the seat upstream ("SUS")
position.
|
Degree
Open
% Full Cv
|
10°
1.5%
|
20°
6%
|
30°
14%
|
40°
25.2%
|
50°
38%
|
60°
55%
|
70°
75%
|
80°
97%
|
90°
100%
|
| 2" |
150 |
1.5
|
6
|
14
|
25
|
39
|
56
|
76
|
99
|
102
|
| |
300 |
1.4
|
6
|
13
|
24
|
36
|
52
|
71
|
95
|
100
|
| |
600 |
1.4
|
5
|
13
|
23
|
35
|
51
|
70
|
90
|
93
|
| 2-1/2" |
150 |
2.2
|
9
|
21
|
37
|
56
|
80
|
110
|
142
|
146
|
| |
300 |
2.1
|
8
|
19
|
34
|
52
|
75
|
102
|
136
|
143
|
| |
600 |
2.0
|
8
|
19
|
33
|
51
|
73
|
100
|
130
|
133
|
| 3" |
150 |
3.4
|
14
|
32
|
57
|
87
|
125
|
171
|
221
|
228
|
| |
300 |
3.2
|
13
|
30
|
53
|
81
|
117
|
159
|
212
|
223
|
| |
600 |
3.1
|
12
|
29
|
52
|
79
|
114
|
156
|
202
|
208
|
| 3-1/2" |
150 |
5.3
|
21
|
49
|
88
|
132
|
192
|
261
|
338
|
349
|
| |
300 |
4.8
|
19
|
45
|
80
|
121
|
176
|
240
|
320
|
336
|
| 4" |
150 |
6.8
|
27
|
63
|
114
|
171
|
248
|
338
|
437
|
451
|
| |
300 |
6.2
|
25
|
58
|
104
|
157
|
228
|
310
|
414
|
435
|
| |
600 |
5.8
|
23
|
54
|
98
|
147
|
213
|
290
|
375
|
387
|
| 5" |
150 |
10.8
|
43
|
100
|
180
|
271
|
392
|
535
|
692
|
714
|
| |
300 |
9.8
|
40
|
92
|
165
|
248
|
361
|
491
|
655
|
688
|
| 6" |
150 |
16.5
|
66
|
154
|
278
|
419
|
607
|
827
|
1070
|
1103
|
| |
300 |
14.9
|
60
|
139
|
250
|
377
|
546
|
744
|
992
|
1041
|
| |
600 |
14.7
|
59
|
137
|
247
|
372
|
538
|
734
|
950
|
979
|
| 8" |
150 |
30.9
|
124
|
289
|
520
|
784
|
1135
|
1584
|
2002
|
2064
|
| |
300 |
27.3
|
109
|
255
|
459
|
692
|
1001
|
1365
|
1820
|
1911
|
| |
600 |
26.8
|
107
|
250
|
451
|
679
|
983
|
1341
|
1734
|
1788
|
| 10" |
150 |
52.8
|
211
|
492
|
886
|
1336
|
1934
|
2638
|
3411
|
3517
|
| |
300 |
45.6
|
183
|
426
|
767
|
1156
|
1673
|
2282
|
3042
|
3194
|
| |
600 |
41.2
|
165
|
384
|
692
|
1044
|
1511
|
2060
|
2665
|
2747
|
| 12" |
150 |
72.6
|
290
|
677
|
1219
|
1838
|
2660
|
3628
|
4690
|
4837
|
| |
300 |
63.3
|
253
|
590
|
1063
|
1602
|
2319
|
3163
|
4217
|
4428
|
| |
600 |
58.4
|
233
|
545
|
981
|
1479
|
2140
|
2918
|
3774
|
3891
|
| 14" |
150 |
90
|
392
|
914
|
1646
|
2481
|
3592
|
4898
|
6530
|
6857
|
| |
300 |
81
|
326
|
760
|
1368
|
2063
|
2986
|
4072
|
5430
|
5702
|
| |
600 |
73
|
292
|
682
|
1228
|
1838
|
2680
|
3655
|
4727
|
4873
|
| 16" |
150 |
132
|
531
|
230
|
2229
|
3361
|
4865
|
6634
|
8845
|
9287
|
| |
300 |
109
|
435
|
1015
|
1827
|
255
|
3988
|
5438
|
7850
|
8243
|
| |
600 |
96
|
385
|
899
|
1619
|
2423
|
3533
|
4818
|
6231
|
6424
|
| 18" |
150 |
171
|
684
|
1596
|
3873
|
4332
|
6270
|
8550
|
11270
|
11400
|
| |
300 |
139
|
555
|
1295
|
2331
|
3515
|
5088
|
6938
|
9250
|
9712
|
| 20" |
150 |
207
|
828
|
1932
|
3478
|
5244
|
7590
|
10350
|
13800
|
14420
|
| |
300 |
158
|
630
|
1470
|
2646
|
3990
|
5775
|
7875
|
10150
|
10658
|
| 24" |
150 |
315
|
1260
|
2940
|
5292
|
7890
|
11550
|
15750
|
21000
|
22050
|
| |
300 |
242
|
966
|
2254
|
4057
|
6118
|
8855
|
12075
|
16100
|
16205
|
| 30" |
150 |
491
|
1965
|
4585
|
8253
|
12445
|
18012
|
24563
|
32750
|
34388
|
| |
300 |
404
|
1614
|
3766
|
6779
|
10222
|
14795
|
20175
|
26900
|
28245
|
| 36" |
150 |
707
|
2830
|
6602
|
11884
|
17920
|
25938
|
35370
|
45745
|
47160
|
| 42" |
150 |
963
|
3851
|
8987
|
16176
|
24392
|
35304
|
48143
|
65564
|
64190
|
| 48" |
150 |
1258
|
5030
|
11738
|
21128
|
31859
|
46111
|
62881
|
81324
|
83840
|
Cf Factors
The critical
flow factor, Cf, expresses the valve pressure ratio. It is equivalent
to FL in ISA nomenclature.
| Disc
Degree Opening |
15° |
20° |
25° |
30° |
35° |
40° |
45° |
50° |
55° |
60° |
65° |
70° |
75° |
80° |
85° |
90° |
| Seat
Upstream |
.95 |
.91 |
.84 |
.81 |
.78 |
.80 |
.77 |
.74 |
.74 |
.73 |
.70 |
.66 |
.63 |
.60 |
.57 |
.53 |
| Seat
Downstream |
.94 |
.89 |
.84 |
.82 |
.80 |
.77 |
.75 |
.72 |
.69 |
.66 |
.63 |
.60 |
.58 |
.55 |
.54 |
.53 |
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