Brochure

107F-27855-10
VB-9313 Water Flow
Coefficient and Capacity
C
v
=
GPM
∆P =
GPM
C
v
( )
GPM = C
v
∆P
2
∆P
Proportional to Blend Water Flows
Proportional valves used to blend two water flows control the heat output by varying the water temperature to the load at constant flow. These
valves do not require high pressure drops for good control results. They can be sized for a pressure drop of 20% of the “available pressure” or
equal to 25% of the pressure drop through the load at full flow.
Water Table
Water Capacity in Gallons Per Minute for VB-9313 Series.
Valve Body
Part Number
Cv
Rating
Differential Pressure (ΔP in psi)
1 2 3 4 5 6 7 8 9 10 15 20 25 30 35
VB-9313-0-5-12
74 74 105 128 148 165 181 196 209 222 234 287 331 370 405 438
VB-9313-0-5-13
101 101 143 175 202 226 247 267 286 303 319 391 452 505 553 598
VB-9313-0-5-14
170 170 240 294 340 380 416 450 481 510 538 658 760 850 931 1006
VB-9313-0-5-15
290 290 410 502 580 648 710 767 820 870 917 1123 1297 1450 1588 1716
VB-9313-0-5-16
390 390 552 675 780 872 955 1032 1103 1170 1233 1510 1744 1950 2136 2307
Cavitation Limitations on Valve Pressure Drop
A valve selected with too high a pressure drop can cause
erosion of discs and/or wire drawing of the seat. In addition,
cavitation can cause noise, damage to the valve trim (and pos-
sibly the body), and choke the flow through the valve.
Do not exceed the maximum differential pressure (pressure
drop) for the valve selected.
The following formula can be used on higher-temperature water
systems, where cavitation could be a problem, to estimate the
maximum allowable pressure drop across the valve:
Pm = 0.5 (P1 – Pv)
Where:
Pm = Maximum allowable pressure drop
P1 = Absolute inlet pressure (psia)
Pv = Absolute vapor pressure (psia) (Refer to the table below.)
Note: Add 14.7psi to the gauge supply pressure to obtain the
absolute pressure value.
For example, if a valve is controlling 200°F water at an inlet
pressure of 18psig, the maximum pressure drop allowable
would be:
Pm = 0.5 [(18 + 14.7) – 11.53] = 10.6psi (Vapor pressure of
200°F water is 11.53psi.)
Therefore, if the pressure drop for this valve is less than
10.6psi, cavitation should not be a problem.
Systems where cavitation is shown to be a problem can some-
times be redesigned to provide lower inlet velocities. Valves
having harder seat materials should be furnished if inlet veloci-
ties cannot be lowered.
For additional valve sizing information, see the Vx-8xxx Selec-
tion Guide, F-27199.
Close-off Ratings (Unless Otherwise Specified)
Nominal actuator close-off ratings are based on ANSI V with EPDM
discs; and PTFE discs in steam applications. Metal-to-metal trim, such
as brass 3-Way and high-temperature stainless, are designed for ANSI
III (0.1-% leakage).
Note: Valve body and actuator size determine the close-off capabili-
ties.
Vapor Pressure of Water Table
Water
Temp.
(°F)
Vapor
Pressure
(psia)
Water
Temp.
(°F)
Vapor
Pressure
(psia)
Water
Temp.
(°F)
Vapor
Pressure
(psia)
Water
Temp.
(°F)
Vapor
Pressure
(psia)
40 0.12 90 0.70 140 2.89 190 9.34
50 0.18 100 0.95 150 3.72 200 11.53
60 0.26 110 1.28 160 4.74 210 14.12
70 0.36 120 1.69 170 5.99 220 17.19
80 0.51 130 2.22 180 7.51 230 20.78
VB-8xx3/9313 Close-Off
Pressure Capability
C
v
Equation
Where:
C
v
= Coefficient of flow
GPM = U.S. gallons per minute (60°F, 15.6°C)
∆P = Differential pressure in psi (pressure drop)
Seat Leakage Classes
ANSI/FCI 70-2
Leakage Class
Maximum Seat Leakage
Class II 0.5% of rated Cv
Class III 0.1% of Rated Cv
Class IV 0.01% of Rated Cv
Class V
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5. VB-8/9000 Globe Valves
Sizing and Selection
5. VB-8/9000 Globe Valves
Sizing and Selection