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V V e e n n t t P P i i p p i i n n g g
ASHRAE Standard 15
5
2
2
0.214d
(P
– P
0
2
L =
2
fC
R
For CenTraVac™ chillers using a rupture disk relief:
•
L = equivalent length of discharge piping, ft (m)
•
C
= rated capacity as stamped on the relief device
r
in lb/min (kg/s), or SCFM multiplied by 0.0764 lb/
min (convert multiplier in lb/min to kg/s for SI)
C
= C C value from the preceding table (convert C C
r
in lb/min to kg/s for SI)
•
f = Moody friction factor in fully turbulent flow
40
)
d * ln(P
/ P
)
0
2
–
6f
•
d = inside diameter of pipe or tube, in. (mm)
•
ln = natural logarithm
•
P
= absolute pressure at outlet of discharge piping,
2
psi (kPa)
•
P
= allowed back pressure (absolute) at the outlet
0
of pressure relief device, psi (kPa)
P
= (0.50 P) + atmospheric pressure
0
N N o o t t e e : : For rupture disks on CenTraVac™ chillers, P
is 15 lb (6.8 kg). Atmospheric pressure is at
the elevation of the installation above sea
level; a default value is the atmospheric
pressure at sea level, 14.7 psi (101.34 kPa).
CDHF-SVX01N-EN
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