User Guide

F-24386-2 © Copyright 2008 TAC All Rights Reserved. 5
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 ΔP of 80% of gauge inlet pressure.
• For steam pressures greater than 15 psig, use ΔP of 42% of absolute (gauge plus 14.7)
inlet pressure.
• When the C
v
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
See Table-5 for steam capacity of VB-9223 series valves.
C
v
Equation
Where:
C
v
= Coefficient of flow
Q = Lbs. per hour of steam
ΔP = Differential pressure in psi (pressure drop)
P2 = Outlet pressure in psia (absolute) (P2 = Inlet pressure + 14.7 – ΔP)
K = 1 + (0.0007 x °F superheat) (K = 1 for saturated steam)
Table-5 Steam Capacity in Pounds Per Hour for VB-9223 Series.
Valve Body
Part Number
Cv
Rating
Differential Pressure (
ΔP in psi)
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-9223-0-5-12 56 305 826 521 1331 818 1942 1093 2448 1359 2860 1620 3271 1879 3683 2136 4095
VB-9223-0-4-12 65 354 958 604 1545 949 2254 1268 2842 1577 3320 1881 3797 2181 4275 2480 4753
VB-9223-0-4-13
VB-9223-0-5-13
85 463 1253 790 2021 1241 2947 1658 3716 2062 4341 2459 4966 2852 5590 3243 6215
VB-9223-0-5-14 145 790 2138 1348 3447 2118 5028 2829 6340 3518 7405 4195 8471 4865 9536 5532 10,602
VB-9223-0-5-15 235 1281 3465 2184 5587 3432 8149 4585 10,275 5701 12,002 6799 13,729 7885 15,455 8965 17,182
VB-9223-0-5-16 350 1907 5161 3253 8321 5112 12,136 6829 15,303 8491 17,875 10,126 20,447 11,744 23,019 13,352 25,591
C
v
=
QK
Q=
K
ΔP • P2
3
ΔP • P2
3C
v