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