Spring 2003
10.450 Process Dynamics, Operations, and Control
Problem Sets  8
1.
You have an 1800 kg h
1
stream of hexane at 100°C. Calculate the pressure drop for a fully
open valve of C
v
= 17.
estimating pressure drop through fully open valve, given mass flow and Cv
mass flow
density
Cv
ref density
calculate volumetric flow
w
F
=
0.000862 m3 s1
r
calculate pressure drop
2
r
�
F
�
2586.731 Pa
0.375076 psi
D
P
=
r
r
�
�
Ł
C
v
�
�
ł
1800
kg h1
580
kg m3
17
gal.in.min1.lbf0.5
999
kg m3
0.5
kg s1
1.29151E05 m4 s1 N0.5
Of course, you realize that the numbers shown in this calculation sheet would be rounded to a
more realistic precision for reporting results: 2590 Pa.
2.
Environmental disaster! There was a spill of BaD
4
StUF
2
from a tank; you are required to
estimate the magnitude of the release. From checking the records, you find that the valve
was open at 40% for 17 s, that it is an equalpercentage valve whose characteristics are
represented by a rangeability of 40, and C
v
is 23. The tank was under nitrogen blanket at 1.2
atm absolute, the temperature was 45°C, liquid level was 80%, ambient temperature was 8°C.
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 Spring '09
 thw
 Fluid Dynamics, Mass, Mass flow rate

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