Vent Piping
38
CVHH-SVX001A-EN
•
L = equivalent length of discharge piping, feet
•
C
r
= rated capacity as stam ped on the relief device in
SCFM (conversion: lb/m in = SCFM * 0.0764)
C
r
= C value in lb/m in from
Table 9, p. 37
•
f = M oody friction factor in fully turbulent flow
•
d = inside diam eter of pipe or tube, in.
•
ln = natural logarithm
•
P
2
= absolute pressure at outlet of discharge piping, psi
(atm ospheric pressure)
•
P
0
= allow ed back pressure (absolute) at the outlet of
pressure relief device, psi
P
0
= (0.15 P) + atm ospheric pressure
Figure 24.
Rupture disk vent pipe sizing (IP units); for use w ith
Table 9, p. 37
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
6 NPS ( 150 DN)
6.06 in. ( 154 m m )
f= 0.0149
4 NPS ( 100 DN)
4.03 in. ( 102 m m )
f= 0.0163
3 NPS ( 80 DN)
3.07 in. ( 78 m m )
f= 0.0173
5 NPS ( 125 DN)
5.05 in. ( 128 m m )
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
1000
100
10
100
1000
10
L = Pipe Le n gt h ( Equ iv a le n t Fe e t )
( Fe e t x 0 .3 0 5 = M e t e r s)
“
C
”
V
a
lu
e
(l
b
/m
in
)
ASHRAE Standard 15
L =
0.214d
5
(P
2
0
- P
2
2
)
-
d * ln(P
0
/ P
2
)
fC
2
R
6f
Содержание CVHH
Страница 110: ......
