Brochure

F-27855-10104
Steam
Two-Position
Two-position zone valves and direct radiation valves are normally sized using a minimum of 10% of inlet pressure (psig).
Proportional
Proportional control valves are normally sized using:
• For low pressure (15 psig or less), use ∆P of 80% of gauge inlet pressure.
• For steam pressures greater than 15 psig, use ∆P of 42% of absolute (gauge plus 14.7) inlet pressure.
• When the Cv required is between two valve sizes, select the larger size. Do not size steam valves using a pressure drop greater than 42%
of the absolute inlet pressure.
Steam Table
Steam Capacity in Pounds Per Hour for VB-82x3 Series
Valve Body
Part Number
Cv
Rating
Differential Pressure (DP in psi)
a
2 psig
Inlet
5 psig
Inlet
10 psig
Inlet
15 psig
Inlet
20 psig
Inlet
25 psig
Inlet
30 psig
Inlet
35 psig
Inlet
0.2 1.6 0.5 4 1 8 1.5 12 2 14 2.5 16 3 18 3.5 20
VB-82x3-0-5-12
56 305 826 520 1331 818 1942 1093 2448 1359 2860 1620 3271 1879 3683 2136 4094
VB-82x3-0-5-13
85 463 1253 790 2021 1241 2947 1658 3716 2062 4341 2459 4965 2852 5590 3242 6214
VB-82x3-0-5-14
145 790 2138 1348 3447 2118 5027 2829 6339 3518 7405 4195 8470 4865 9536 5531 10601
VB-82x3-0-5-15
240 1308 3539 2231 5706 3505 8322 4683 10493 5823 12257 6943 14021 8053 15784 9156 17548
VB-82x3-0-5-16
370 2016 5456 3439 8796 5404 12830 7219 16177 8977 18896 10704 21615 12415 24334 14115 27053
a - Left column shows # per hour with a 10 % pressure drop and right column shows # per hour with an 80% pressure drop.
Cv Equation for Steam
C
v
=
Q x K
Q =
K
∆P x P2
3
3C
v
∆P x P2
Where:
Cv = Coefficient of flow.
Q = Flow rate of steam that will pass through fully open valve, measured as pounds per hour of steam.
∆P = Differential pressure (pressure drop), measured in psi.
P2 = Outlet pressure, measured in psia (absolute pressure). P2 = Inlet pressure + 14.7 – ∆P.
K = 1 + (0.0007 x °F superheat). K = 1 for saturated steam.
VB-82x3 Steam Capacity &
Vapor Pressures
5. VB-8/9000 Globe Valves
Sizing and Selection
5. VB-8/9000 Globe Valves
Sizing and Selection