Trane CenTraVac CVHE - Page 46

46
CVHE-SVX005C-EN
L =
0.214d
5
(P
2
0
– P
2
2
)
–
d * ln(P
0
/ P
2
)
fC
2
R
6f
ASHRAE Standard 15
For CenTraVac™ chillers using a rupture disk relief:
• L = equivalent length of discharge piping, ft (m)
• C
r
= rated capacity as stamped on the relief device in
lb/min (kg/s), or SCFM multiplied by 0.0764 lb/min
(convert multiplier in lb/min to kg/s for SI)
C
r
= C value from the preceding table (convert C in
lb/min to kg/s for SI)
• f = Moody friction factor in fully turbulent flow
• d = inside diameter of pipe or tube, in. (mm)
• ln = natural logarithm
• P
2
= absolute pressure at outlet of discharge piping, psi
(kPa)
• P
0
= allowed back pressure (absolute) at the outlet of
pressure relief device, psi (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
Note: On CenTraVac™ chillers, P is 15 psi (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).
Vent Piping