Specifications

VALVE SIZING
T
o properly size an automatic control valve you need to know the following:
• Highest and Lowest inlet pressures
•
Outlet pressure
•
Maximum flow requirements
• Minimum flow requirements
Step 1: Utilize the high flow chart and select the flow as found on the horizon-
t
al axis which corresponds with your maximum flow requirements.
Step 2: From this point draw a vertical line until you intersect with the horizon-
t
al line corresponding with the minimum differential pressure. (Your minimum
differential pressure will be the lowest inlet pressure minus the desired outlet
p
ressure, this is also known as the delta P.)
Step 3: From this point move right to the first valve size line. This will be the
m
inimum valve size which should be used on intermittent flow of 25 ft./sec. If
maximum flow is continuous, then do not exceed the GPM (20 FT./sec.) listed
on the maximum continuous flow table.
Step 4: Utilize the flow chart and select the maximum differential pressure as
found on the vertical axis. (Your maximum differential pressure will be the high-
e
st inlet pressure minus the desired outlet pressure, this is also known as
the delta P.)
S
tep 5: From this point draw a horizontal line until you intersect with the line
corresponding to the valve size as selected in step 3.
S
tep 6: From this point draw a vertical line down to the horizontal axis. This
will be the minimum flow capabilities of the valve based on these variables.
Notes: 1) If the minimum flow capability obtained from step 6 is above your
a
ctual minimum flow requirements, you should consider a parallel installa-
t
ion. Using the minimum flow capability, begin at step 1 to select the size you
will need for this low-flow by-pass.
2) Use the cavitation chart and determine if the intersection of the
inlet and outlet pressures falls in the shaded area. If so, you should consider a
s
eries installation. Both valves should be sized in accordance with the above
steps.
MAXIMUM CONTINUOUS FLOW CHART
SIZE 1
1
/4"1
1
/2" 2" 2
1
/2" 3" 4" 6" 8" 10" 12" 14" 16"
FLOW (GPM) 93 93 210 300 460 800 1800 3100 4900 7000 8500 11000
31