Chapter hvac engineering Fundamentals: Part 1 Introduction

176
Chapter Six
Figure 6.20
Open expansion
tank.
The following ASME formula for determining the size of a closed
system expansion tank is valid for temperatures between 160 and
280
⬚
F.
(0.00047
t
⫺
0.0466)
V
s
V
⫽
(6.2)
t
P
/
P
⫺
P
/
P
a
f
a
o
where
V
t
⫽
minimum volume of expansion tank, gal
V
s
⫽
system volume, gal
t
⫽
maximum operating temperature,
⬚
F
P
a
⫽
pressure in expansion tank when water first enters (usu-
ally atmospheric), ftH
2
O absolute
P
f
⫽
initial fill pressure at tank, ftH
2
O absolute
P
o
⫽
maximum operating pressure at tank, ftH
2
O absolute
For temperatures below 160
⬚
F, a simpler formula may be used:
Design Procedures: Part 4
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