Trane CenTraVac CDHH - Page 43

CDHH-SVX003C-EN
43
L =
7.4381x10
5
(P
2
0
– P
2
2
)
–
d * ln(P
0
/ P
2
)
fC
2
R
500f
ASHRAE Standard 15
d
–15
• L = equivalent length of discharge piping, meters
• C
r
= rated capacity as stamped on the relief device in
SCFM (conversion: kg/s = SCFM * 0.0764 / 132.28)
C
r
= C value from the preceding table (convert C in
kg/s to lb/min for IP; lb/min = (kg/s) / 132.28)
• f = Moody friction factor in fully turbulent flow
• d = inside diameter of pipe or tube, mm
• ln = natural logarithm
• P
2
= absolute pressure at outlet of discharge piping,
kPa (atmospheric pressure)
• P
0
= allowed back pressure (absolute) at the outlet of
pressure relief device, kPa
– If chiller uses a rupture guard:
P
0
= (0.15 P) + atmospheric pressure
– If chiller uses a rupture disk:
P
0
= (0.5 P) + atmospheric pressure
Vent Piping