Honeywell HON HSV086, Operation & Maintenance Manual, Page: 7 / 48

© 2017 Honeywell International Inc
Operation and maintenance manual HON HSV086 7
1.5 Determination of the capacity
To determine the pressure loss of a safety device with fully open valve, you may use this
formula:
 
 
 
pi Cg
Tu d Qn
p
. . 57 , 13
273 . .
2
2

 
For natural gas with q
n
= 0.831 kg/m³
d = 0.643
When using other gasses
d= q
n
gas / 1.29
with Q
n
= flow rate in m
n
3
/h
p
i
= inlet pressure in bar (abs)
Cg = capacity rate
d = relative density (air = 1)
Tu = inlet temperature of the gas ( o C)
q
n
= gas density (Tu = 273 K = 0
o
C)
DN 1" 2" 3" 4" 6" 8" 10" 12" 16" 20" 24"
C
g
480 1950 4300 7050 15100 26060 40800 60050 104150 166640 287953
Table II: Capacity rates C
g
(up to 600#, high pressures on request)
To limit the flow forces we would advise not to exceed the following flow rate. You
have to use the formula below for this purpose.
in which D
1
= nominal diameter in mm
pi
min
= minimum inlet pressure in bar (abs)
Q
max
= maximum flow in m
n
3
/h
K= 100 for DN = 1” up to 6”
K= 200 for DN = 8” up to 12”
K= 300 for DN =16” up to 24”
p
D
Q
min i
1
max
K
