User Guide

F-24392-2 © Copyright 2008 TAC All Rights Reserved. 3
Flow Characteristics
Three-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-1 for typical characteristic of VB-7312 series
valve bodies.
Figure-1 Typical Flow Characteristics.
Rangeability
Rangeability is the ratio of rated flow to the minimum controllable flow through a valve. For
mixing valves, control begins as soon as plug displacement allows flow. Thus, three-way
valve rangeability normally exceeds 500:1, which is the reciprocal of 0.2% nominal leakage.
Temperature/Pressure Ratings
See Figure-2 for temperature and pressure ratings. Consult the appropriate valve linkage
general instruction sheet for the effect of valve body ambient temperatures on specific
actuators. Ratings conform with published values and disclaimer.
VB-7312-0-4-P (45° SAE Flared Cast Bronze Body)
Standards: Pressure to ANSI B16.15 Class 250 with 400 psig up to 150°F decreasing to
321 psig at 281°F
Materials: Bronze, ASTM B584
Figure-2 Temperature and Pressure Ratings for VB-7312 Series Valve Bodies.
Rated Flow
StrokeStem In
Stem Out
"A" Port
"B" Port
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0%
20% 40% 60% 80%
100%
50
(345)
250 (121)
200 (93)
150 (65)
100 (38)
50 (10)
300 (149)
150
(1034)
250
(1724)
350
(2458)
100
(689)
Pressure — psig (kPa)
321 psig
(2218 kPa)
Temperature — °F (°C)
200
(1379)
300
(2068)
400
(2758)
Maximum Media
Temperature
281°F (138°C)
Minimum Fluid
Temperature
20°F (-7°C)
VB-7312-0-4-P