Data Sheet

Bulletin 71.2:92B
10
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














Figure 6. Safety Override System Installation
 psig 
 psig


psig
psig
Determine the maximum valve flow capacity at
wide-open failure.
Q
max(lb/hr)
=
C
S
P
1
3417 ΔP
SIN DEG
1 + 0.00065 T
sh
C
1
P
1
where:
Q = Steam flow rate, lb/hr
P
1
= Absolute inlet pressure, psia (P1 gauge + 14.7)
C
s
= Wide-open gas sizing coefcient, see Table 5
C
1
= Flow coefcient, see Table 5
T
sh
= Degrees of steam superheat at inlet, °F
ΔP = Pressure drop across regulator, psia
Example Calculation:
where:
C
S
= 74 ΔP = 75 psia / 5.2 bar
C
1
= 35 T
sh
= 0°F
P
1
= 114.7 psia / 7.9 bar
Q
max(lb/hr)
=
Q
max
= 8,330 lb/hr / 3778 kg/hr
341774 x 114.7
1 + 0.00065 x 0 35 114.7
75
SIN DEG