Vent Piping
36
CVHH-SVX001A-EN
•
L = equivalent length of discharge piping, m eters
•
C
r
= rated capacity as stam ped on the relief device in
SCFM (conversion: kg/s = SCFM * 0.0764 / 132.28)
C
r
= C value from
Table 8, p. 35
(convert C in kg/s to lb/
m in for IP; lb/m in = (kg/s) / 132.28)
•
f = M oody friction factor in fully turbulent flow
•
d = inside diam eter of pipe or tube, m m
•
ln = natural logarithm
•
P
2
= absolute pressure at outlet of discharge piping,
kPa (atm ospheric pressure)
•
P
0
= allow ed back pressure (absolute) at the outlet of
pressure relief device, kPa
P
0
= (0.15 P) + atm ospheric pressure
Figure 23.
Rupture disk vent pipe sizing (SI units); for use w ith
Table 8, p. 35
Note: This figure, provided as a r efer ence, is based on ASHRAE St andard 15. Vent line size is t y pically dict at ed by st at e or local code w hich m ay be differ ent
fr om ASHRAE St andar d 15 r equir em ent s.
Pipe Siz e ( I .D .)
fr ict ion f a ct or
150 DN ( 6 NPS)
154 m m ( 6.06 in.)
f = 0.0149
100 DN ( 4 NPS)
102 m m ( 4.03 in.)
f = 0.0163
80 DN ( 3 NPS)
78 m m ( 3.07 in.)
f = 0.0173
125 DN ( 5 NPS)
128 m m ( 5.05 in.)
f = 0.0155
Pip e siz e a s a Fu n ct ion of “C” Va lu e a n d Le n gt h of Ru n
10
1
0
100
1000
10
L = Pipe Le n gt h ( Equ iv a le n t M e t e r s)
( M e t e r s x 3 .2 8 1 = Fe e t )
“
C
”
V
a
lu
e
(k
g
/s)
ASHRAE Standard 15
L =
7.4381x10
-15
d
5
(P
2
0
- P
2
2
)
-
d * ln(P
0
/ P
2
)
fC
2
R
500f
Содержание CVHH
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