Data Sheet
Bulletin 71.4:SR8
6
Table 5. C
v
Coefcients
SPRING
RANGE,
PSIG (bar)
SET
PRESSURE,
PSIG (bar)
C
V
AT % BUILD-UP
Elastomer Diaphragm Metal Diaphragm
NPS 1/2 (DN 15) NPS 1/2 (DN 15)
10% 20% 30% 40% 10% 20% 30% 40%
2 to 8
(0,14 to 0,55)
2 (0,14) 0.45 0.55 0.65 0.75
Not Available
5 (0,34) 0.45 0.67 0.84 0.99
8 (0,55) 0.50 0.80 1.03 1.22
5 to 25
(0,34 to 1,7)
5 (0,34) 0.35 0.49 0.62 0.80 0.32 0.36 0.40 0.47
15 (1,0) 0.59 0.94 1.13 1.26 0.40 0.55 0.67 0.81
25 (1,7) 0.71 1.15 1.36 1.40 0.44 0.64 0.78 0.96
10 to 50
(0,69 to 3,4)
10 (0,69) 0.40 0.65 0.87 1.10 0.35 0.42 0.50 0.57
15 (1,0) 0.54 0.87 1.04 1.21 0.38 0.49 0.62 0.74
30 (2,1) 0.76 1.22 1.30 1.37 0.43 0.59 0.82 0.98
45 (3,1) 0.86 1.39 1.40 1.40 0.45 0.64 0.91 1.09
50 (3,4) 0.89 1.40 1.40 1.40 0.45 0.66 0.93 1.12
35 to 100
(2,4 to 6,9)
35 (2,4) 0.60 0.95 1.24 1.40 0.42 0.60 0.75 0.94
50 (3,4) 0.69 1.10 1.35 1.40 0.46 0.69 0.89 1.11
75 (5,2) 0.77 1.23 1.40 1.40 0.50 0.77 1.02 1.27
100 (6,9) 0.82 1.30 1.40 1.40 0.53 0.82 1.09 1.36
75 to 125
(5,2 to 8,6)
75 (5,2) 1.16 1.40 1.40 1.40 1.12 1.40 1.40 1.40
100 (6,9) 1.13 1.40 1.40 1.40 1.10 1.40 1.40 1.40
125 (8,6) 1.23 1.36 1.39 1.02 1.40 1.40
Shaded areas indicate conditions where maximum differential pressure for the spring range is exceeded.
SPRING
RANGE,
PSIG (bar)
SET
PRESSURE,
PSIG (bar)
C
V
AT % BUILD-UP
Elastomer Diaphragm Metal Diaphragm
NPS 3/4 (DN 20) NPS 3/4 (DN 20)
10% 20% 30% 40% 10% 20% 30% 40%
2 to 8
(0,14 to 0,55)
2 (0,14) 0.58 0.67 0.90 1.07
Not Available5 (0,34) 0.82 1.38 2.08 2.27
8 (0,55) 1.04 1.94 2.96 3.10
5 to 25
(0,34 to 1,7)
5 (0,34) 0.60 0.87 1.16 1.44 0.51 0.56 0.64 0.75
15 (1,0) 1.04 2.10 2.69 2.82 0.56 0.70 0.86 1.03
25 (1,7) 1.26 2.67 3.10 3.10 0.59 0.76 0.95 1.15
10 to 50
(0,69 to 3,4)
10 (0,69)
0.62 0.92 1.28 1.70 0.47 0.55 0.62 0.73
15 (1,0) 0.80 1.35 1.70 2.11 0.51 0.65 0.78 0.93
30 (2,1) 1.09 2.02 2.34 2.72 0.59 0.80 1.02 1.23
45 (3,1) 1.23 2.34 2.64 3.00 0.62 0.87 1.13 1.37
50 (3,4) 1.26 2.41 2.70 3.06 0.63 0.88 1.16 1.40
35 to 100
(2,4 to 6,9)
35 (2,4) 0.91 1.83 2.71 3.10 0.56 0.73 0.89 1.06
50 (3,4) 1.34 2.36 3.00 3.10 0.62 0.83 1.09 1.35
75 (5,2) 1.72 2.83 3.10 3.10 0.67 0.93 1.27 1.59
100 (6,9) 1.94 3.10 3.10 3.10 0.70 0.98 1.36 1.73
75 to 125
(5,2 to 8,6)
75 (5,2) 1.66 2.80 3.04 3.10 1.01 1.58 1.92 2.10
100 (6,9) 1.96 3.10 3.10 3.10 1.01 1.33 1.85 2.21
125 (8,6) 2.21 3.10 3.10 1.01 1.47 1.96
Shaded areas indicate conditions where maximum differential pressure for the spring range is exceeded.
Table 5. C
v
Coefcients (continued)