Selection Guide

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3-Way Valves: 3-way mixing valves are designed so that the flow from either of the inlet ports to the outlet is approximately
linear, which means the total flow from the outlet is almost constant over the stroke of the valve stem. See Figure-2 for typical
flow characteristics of the VB-731x and VB-931x series valve bodies.
Rangeability
Rangeability is the ratio of rated flow to the minimum controllable flow through a valve.
2-Way Valves: Table-5 lists the rangeability for VB-72xx and VB-92xx series globe valves. Refer to the model charts on the
following pages for detailed valve information.
3-Way Valves: For mixing valves, control begins as soon as plug displacement allows flow. Thus, the rangeability of 3-way
valves normally exceeds 500:1, which is the reciprocal of 0.2% nominal leakage.
Table-5 Rangeability.
Nominal Valve Size
Port Code (P)
Nominal
Rangeability
Standard Metric
1/2" 15 mm
15:1
215:1
325:1
440:1
3/4" 20 mm
550:1
660:1
1" 25 mm
760:1
875:1
1-1/4" 32 mm 9 75:1
1-1/2" 40 mm 10 75:1
2" 50 mm 11 75:1
2-1/2” 65 mm 12 75:1
3” 80 mm 13 75:1
4” — 14 75:1
5” — 15 75:1
6” — 16 75:1
StrokeStem Up
Stem Down
0% 20% 40% 60% 80% 100%
Rated Flow
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
"A" Port
"B" Port
Figure-2 Typical Flow Characteristics.