Page 78 
U-Throated Flume 
ABSOLUTE 
If the flow calculation is to be absolute P702 = 1 the flow will be calculated 
using the formula:  q = (2/3)
1.5
g
n
0.5
C
u
C
v
C
d
bh
1.5 
Where:  q   = flowrate                  
g
n
 = gravitational acceleration  (nominal value = 980.66 cm/s
2
)  
h   = head        
C
u
= shape coefficient calculated by Ultra Twin P724                                                  
C
v
 = velocity coefficient calculated by Ultra Twin P721    
C
d 
= discharge coeffecient calculated by Ultra twin P722     
b   = throat width P711  
 
RATIOMETRIC 
U-Throated Flume 
If the flow calculation is to be ratiometric P702 = 2 the flow will be 
calculated using the formula:   
q= q
cal
(C
v
/C
vcal
)(C
d
/C
dcal
)(C
u
/C
ucal
)(h/h
cal
)
1.5
 
Where:  q        =   flowrate         
q 
cal 
= flowrate at maximum head P705                                  
Cv   = velocity coefficient calculated by Ultra Twin P721 
Cv
cal 
= velocity coefficient at maximum head    
Cd      = discharge coeffecient calculated by Ultra Twin P722 
Cd
cal 
= discharge coefficient at maximum head 
Cu      = shape coefficient  P724                                              
Cu
cal
  = shape coefficient at maximum head            
h         = head h
cal 
  = maximum head P704