Flow Calculation - YOKOGAWA DY025 User Manual

7.6 Flow Calculation

(1) Flow Calculation
The flowrate is calculated with the following equations based
on the N number of generated vortices:
(a) Flowrate (in engineering units)
1
. ε . ε . ε
RATE=N .
t
f e
KT=KM . U . {1–4.81×(Tf–15)×10
KT
KT=KM . {1–2.627×(Tf–59)×10
(b) Flowrate (%)
1
RATE(%)=RATE .
F
(c) Totalized value
TOTAL=TOTAL +
TOTAL=RATE · t ·
(d) Pulse output frequency
PULSE FREQ=RATE ·
1
PULSE FREQ= N ·
(e) Velocity
1 1
V=N . . . U
t
KT
KT
(f) Reynolds number
1
Red=V . D . ρ ×1000
.
µ
f
1
Red=V . D . ρ ×124
.
µ
f
where N: Number of input pulses (pulse)
∆t:
Time corresponding to N (seconds)
ε
: Instrumental error correction factor
f
ε
: Expansion correction factor for compressive
e
fluid
ε
: Reynolds number correction factor
r
KT: K-factor at operating conditions (pulses/
litre) (pulse/gal)
KM: K-factor at temperature 15°C (59°F)
U : Unit conversion factor for K-factor
KT
U : Flow unit conversion factor (Refer to item
k
(2))
U (user): Flow unit conversion factor for user's unit
k
U : Factor corresponding to flow unit time (ex./
TM
m (minute) is 60.)
. 1
. U . U
r KT k TM
.... (7.1.1)
–5 }.... (Metric Units)
.... (7.1.2)
–5
} .... (English Units)
.... (7.1.3)
.... (7.2)
S
TOTAL
1 1
·
.... (7.3)
T U
R TM
1 1
· .... (7.4.1)
P U
R TM
1
t · .... (Unscaled pulses)
P
R
.... (7.4.2)
4
.
.... (7.5)
2
πD
.... (Metric Units)
.... (7.6.1)
.... (English Units)
.... (7.6.2)
P : Pulse rate (ex. E+ 3 is 10
R
T : Temperature at operating conditions (°C)
f
(°F)
F : Flowrate span
S
T : Total rate
R
D: Internal diameter (m) (inch)
µ :
Viscosity (cP)
ρ
: Density at operating conditions (kg/m
f
3
ft )
(2) Flow Conversion Factor (Uk)
Flow conversion factor Uk is obtained by carrying out the
following computation depending on the selection of the fluid
to be measured and the flow unit.
(a) Steam
M (Mass flowrate): U
Qf (Flowrate at operation): U
(b) Gas
Qn: (Flowrate at STP):
P T
f
U = ·
k
P T
n
5
P
f
9
U =
·
k
5
P
n
9
M: (Mass flowrate): U
Qf: (Flowrate): U
U
(c) Liquid
Qf: (Flowrate): U
U
M (Mass flowrate): U
(d) User's unit
U =U (user)
k k
Uρ : Unit conversion factors of density.
f
U , U , U
k(kg) k(Nm3) k(m3)
U , U , U , U
k(lb) k(Btu) k(scf)
7-6
7. MAINTENANCE
3 .)
. Uρ . U
=ρ (kg)
k f f k
. U
U =ρ ( b)
k f k
3
=U (m )
k k
U =U (acf)
k k
1
+ 273.15
n
· U
·
k (Nm 3 )
K
+ 273.15
f
1
(T -32) + 273.15
n
U
· ·
K
(T -32) + 273.15
n
=ρ . Uρ . U (kg)
k f f k
U =ρ . Uρ . U ( b)
k f f k
3
=U (m )
k k
=U (acf)
k k
=U (m 3 )
k k
=U (acf)
k k
. U (kg)
=ρ
k f
. U ( b)
U =7.481×ρ
k f
7.481 is a conversion factor of U.S
gal into acf
: Unit conversion factors
k(acf)
IM 01F06A00-01E
3
) ( b/
.... (7.7.1)
.... (7.7.2)
.... (7.7.3)
.... (7.7.4)
.... (7.8)
k (scf)
.... (7.9.1)
.... (7.9.2)
.... (7.10.1)
.... (7.10.2)
.... (7.11.1)
.... (7.11.2)
.... (7.12.1)
.... (7.12.2)
.... (7.13)