Operating Characteristics for
sizing
¢Ã The size of butterfly valve used for control purpose
should be calculated on the basis of the
operating characteristics.
In order to achieve optimum control,
the flow coefficient ( Cv, Kv ) below need
to be considered
¢Ã Flow Coefficient for STONETOWN Butterfly valves
SIZE |
DISC
OPENING |
20° |
30° |
40° |
50° |
60° |
70° |
80° |
90° |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
Kv |
Cv |
40 |
1½ |
2.6 |
3 |
4.3 |
5 |
9.5 |
11 |
16 |
18 |
22 |
26 |
39 |
45 |
60 |
70 |
69 |
80 |
50 |
2 |
6.7 |
8 |
7.8 |
9 |
16 |
18 |
24 |
28 |
48 |
55 |
62 |
72 |
95 |
110 |
116 |
135 |
65 |
2½ |
8.6 |
10 |
13 |
15 |
23 |
27 |
38 |
44 |
73 |
85 |
95 |
110 |
145 |
168 |
181 |
210 |
80 |
3 |
13 |
15 |
20 |
23 |
34 |
39 |
56 |
65 |
112 |
130 |
142 |
165 |
216 |
250 |
267 |
310 |
100 |
4 |
23 |
27 |
35 |
41 |
61 |
71 |
99 |
115 |
198 |
230 |
259 |
300 |
401 |
465 |
466 |
540 |
125 |
5 |
50 |
58 |
74 |
86 |
129 |
150 |
211 |
245 |
414 |
480 |
526 |
610 |
845 |
980 |
948 |
1100 |
150 |
6 |
83 |
96 |
121 |
140 |
211 |
245 |
345 |
400 |
677 |
785 |
871 |
1010 |
1392 |
1615 |
1647 |
1910 |
200 |
8 |
142 |
165 |
211 |
245 |
354 |
410 |
591 |
685 |
1099 |
1275 |
1478 |
1715 |
2302 |
2670 |
2746 |
3185 |
250 |
10 |
220 |
255 |
328 |
380 |
560 |
650 |
974 |
1130 |
1810 |
2100 |
2328 |
2700 |
3664 |
4250 |
4224 |
4900 |
300 |
12 |
319 |
370 |
466 |
540 |
819 |
950 |
1353 |
1570 |
2629 |
3050 |
3405 |
3950 |
5129 |
5950 |
6336 |
7350 |
350 |
14 |
388 |
450 |
647 |
750 |
1120 |
1300 |
1905 |
2210 |
3517 |
4080 |
4836 |
5610 |
6964 |
8078 |
9655 |
11200 |
400 |
16 |
552 |
640 |
776 |
900 |
1483 |
1720 |
2405 |
2790 |
4310 |
5000 |
6336 |
7650 |
9284 |
10770 |
11121 |
12900 |
450 |
18 |
630 |
730 |
1078 |
1250 |
1978 |
2295 |
3190 |
3700 |
6078 |
7050 |
7914 |
9180 |
11983 |
13900 |
15086 |
17500 |
500 |
20 |
785 |
910 |
1375 |
1595 |
2457 |
2850 |
3991 |
4630 |
7414 |
8600 |
9914 |
11500 |
15121 |
17540 |
19310 |
22400 |
600 |
24 |
1078 |
1250 |
1974 |
2290 |
3448 |
4000 |
5250 |
6090 |
10776 |
12500 |
14224 |
16500 |
20336 |
23590 |
24397 |
28300 |
¡ß Cv is in imperial units, the
water flow rate in U.S gallons per minute
which passes through the valve giving
a pressure drop of 1 psi at a temperature
of 68¢µ
In metric units the
same coefficient is called Kv and correspond
to the flow rate in m3/h passing through
the valve giving a pressure drop of 1 bar
at a temperature of 20¡É The approximate corresponding
formulas are :
|
|
|
Q = valve flow rate
in gpm (US GPM) ¡âp = pounds
per square inch (psi)
pressure drop through the valve 62.4
= conversion factor for fluids computed
in relation to water D =
is pounds per cu.ft (pct) fluid
density
|
|
Q = valve flow rate
in m3/h ¡âp = pressure drop
through the valve in bar 1000
= conversion factor for fluids
computed in computed in relation
to water relation to water D
= §¸/m3 fluid density
|
The relation
between Cv and Kv, expressed
in the above mentioned unit
of measure is as follows;
Cv = 1.16
Kv
|
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