Troubleshooting – Yokogawa digitalYEWFLO (DY) User Manual
Page 97
IM 1F2B4-01-YIA
Page 92
TROUBLESHOOTING
6.3
F
LOW
COMPUTATION
The flowrate is computed with the following equations based on the N number of generated vortices:
•Flowrate (in engineering units)
RATE = N * 1 *
ε
f
*
ε
e
*
ε
r
*
ε
p
*1 * U
KT
* U
k
* 1
∆
t
KT
S
E
KT = KM * {1 - 4.81 x (Tf - 15) x 10
-5
}
...Metric Units
KT = KM * {1 - 2.627 x (Tf - 15) x 10
-5
}
...English Units
•Flowrate (%)
RATE (%) = RATE * 1
F
S
•Totalized value
TOTAL = N *
ε
f
*
ε
e
*
ε
r
*
ε
p
*1 * U
KT
* U
k
* 1
KT
T
E
TOTAL =
ε
f
*
ε
e
*
ε
r
*
ε
p
*N
...Unscaled
•Velocity
V = N * 1 * 1 * U
KT
* 1
∆
t KT
π
D
2
•Reynolds number
Red = V * D * p
f
* 1 x 1000
...Metric Units
µ
Red = V * D * p
f
* 1 x 124
...English Units
µ
6.3.1
Variable definitions
N
Input pulses counted
Dt
Sample time for N counts (seconds)
ε
r
Reynolds number correction factor (D01 - D03)
ε
p
Pipe schedule correction factor (D05)
ε
e
Expansion correction factor for gas or steam (D06)
ε
f
Flow linearization correction factor (D20 - D30)
KT
K-factor at operating temperature (pulses/litre) (pulses/gal)
KM
K-factor at 15ºC (59ºF) (B06)
U
kt
Unit conversion factor for K-factor
U
k
Flow unit conversion factor (Refer to item (2))
U
k
(user)
Flow unit conversion factor for user's unit
U
TM
Factor corresponding to flow unit time (ex./m (minute) is 60)
S
E
Span factor (ex. E + 3 is 10
3
) (B51)
P
E
Pulse rate (ex. E + 3 is 10
3
) (C03)
T
f
Temperature at operating conditions (ºC) (ºF) (B10)
M
Mass flow
H
Calorimetric flow