<3. Maintenance>
20
IM 01F07A01-02EN
b) Gas
In the case of gas, perform temperature/pressure correction based on the measured
temperature value, and calculate the volumetric flow rate at normal conditions. For the
pressure, use the fixed value input in the parameters or the analog input value from an
external pressure gauge.
Q
n
= Q
f
×{P
f
/ P
n
}×{(T
n
+273.15) / (T
ft
+273.15)}×1 / K
c) Liquid
In the case of liquid, perform a secondary correction for the change in density based on the
temperature.
For the calculation, use the measured temperature value to determine the change in
density.
M = Q
f
×ρ
n
×{1+a1 × (T
ft
-T
n
)×10
-2
+a
2
× (T
ft
-T
n
)
2
×10
-6
}
[Additional notes]
a
1
= {(k
1
-1)×∆T
22
-(k
2
-1)×∆T
12
} / {(∆T
1
×∆T
22
-∆T
2
×∆T
12
)×10
-2
}
a
2
= {(k
1
-1)×∆T
2
-(k
2
-1)×∆T
1
} / {(∆T
12
×∆T
2
-∆T
22
×∆T
1
)×10
-6
}
k
x
= 1+a
1
×∆T
x
×10
-2
+a
2
×∆T
x2
×10
-6
∆T
x
= T
x
-Tn
(x = 1, 2)
M: Mass flow rate
Q
n
: Volumetric flow rate at normal conditions
Q
f
: Volumetric flow rate at operating conditions
T
f
: Temperature at operating conditions (°C)
T
ft
: Measured temperature (°C)
T
n
: Temperature at normal conditions (°C)
P
f
: Pressure at operating conditions (kPa)
P
n
: Pressure at normal conditions (kPa)
K: Deviation factor
ρ
n
: Density at normal conditions (kg/m
3
)
ρ
f
: Density at operating conditions (kg/m
3
)
ρ
ft
: Density determined from measured temperature (kg/m
3
)
U
ρf
. Density unit conversion coefficient
U
k
(kg), U
k
(Nm
3
), U
k
(m
3
): Flow rate unit conversion coefficient
a
1
: Primary correction coefficient for liquid
a
2
: Secondary correction coefficient for liquid
(Example) Using U
k
(kg) coefficient to convert unit from kg
For kg: U
k
(kg) = 1
For metric ton: U
k
(kg) = 0.001
