Bray 40_41 - Manual (Page 11)

Bray/McCannalok HPBV – Dynamic Torques
All information herein is proprietary and confidential and may not be copied or reproduced without the expressed written consent of BRAY INTERNATIONAL, Inc.
The technical data herein is for general information only. Product suitability should be based solely upon customer’s detailed knowledge and experience with their application. Dynamic : 11
For: Condition: Use: Note:
Subchoked
Flow
Pipe and
Valve Size
Equal
• Nominal Valve Size
• Valve Pressure Drop
• Ct from graphs/tables on pg. 12
W/ Pipe
Reducers
• Nominal Valve Size
• Ct from graphs/tables on pg. 12
• Valve Pressure Drop as if valve
were installed in valve-sized
pipe with same flow rate
Choked Flow
Pipe and
Valve Size
Equal
• Nominal Valve Size
• Ct from graphs/tables on pg. 12
• Actual Pressure drop through
valve.
If actual pressure drop at the choked condition is
not known, estimate by evaluating the pressure in
the piping at the valve outlet needed to sustain the
choked flow rate through the piping downstream
of the valve; then subtracting it from the valve inlet
pressure.
W/ Pipe
Reducers
• Nominal Valve Size
• Ct from graphs/tables on pg. 12
• Actual pressure drop through
valve/reducer assembly.
If the pressure drop at the choked condition is
not known, estimate the line pressure just down-
stream of the valve/reducer assembly which is
needed to sustain the choked flow rate of the
valve/reducer assembly through the downstream
piping; then subtract this pressure from the line
pressure just ahead of the valve/reducer assembly,
to get the actual pressure drop.
For: Condition: Use: Note:
Subchoked
Flow
Pipe and
Valve Size
Equal
• Nominal Valve Size
• Valve Pressure Drop
• Ct from graphs/tables on pg. 12
W/ Pipe
Reducers
• Nominal Valve Size
• Ct from graphs/tables on pg. 12
• Valve Pressure Drop (and expansion factor
Y) as if valve were installed in valve-sized
pipe with same flow rate.
In calculating Y, use the line pressure
just upstream of the inlet reducer for p1
and xt from the table on page 10.
Choked Flow
Pipe and
Valve Size
Equal
• Nominal Valve Size
• Gas expansion factor Y of 2/3
• Ct from graphs/tables on pg. 12
•
 p = p1 Fk xt
Use xt from the table on page 10.
W/ Pipe
Reducers
• Nominal Valve Size
• Gas expansion factor Y of 2/3
• Ct from graphs/tables on pg. 12
•
 p = p1 Fk xt
Use the line pressure just upstream
of the inlet reducer for p1 and xt from
the table above in calculating
 p,
on page 10.