Yokogawa EJX930A - Manual (Page 41)

<3. Parameter Setting>
3-30
IM 01C25R02-01E
Table 3.2 Basic Flow Calc Set-up Steps
Step Parameter Contents Remarks
1 Flow Calc Mode Select Basic Mode
2 Fluid Type Select liquid or gas
3 Flow Calc Fixed Input Kfactor Kfactor calculated by Table 3.3 Flow Equation and Kfactor
Calculation
4 Ref SP Input reference static
pressure
This factor is used for gas.
When fluid type is liquid, set 0 to Ref SP(Spb).
5 Ref Temp Input reference temperature
6 Temp K1 Input the density rate of
change per temperature
1degC.
This factor is used for mass flow and normal standard volume flow
of liquid. When fluid type is gas or volume flow of liquid, set 0 to
TempK1. Refer to Table 3.4 Symbol
Equation for Basic flow calculation
The flow equation shown in Table 3.3 is applied to the transmitter by combination of fluid type and flow unit
category.
Table 3.3 Flow Equation and Kfactor Calculation
T0310.ai
Mass Flow
Normal-Standard
Volume Flow
Volume Flow
Mass Flow
Normal-Standard
Volume Flow
Volume Flow
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
Ч 2 Ч ρb
Qm, Qv or Qv_norm
=
Kfactor × ∆ρ × (1+ Temp K1 × (T-Tb))
Fluid Type Flow unit category Kfactor *2 Flow Equation
liquid
Gas
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
Ч 2 Ч ρb / ρ norm
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
× 2 / ρb
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
Ч 2 Ч ρb × 1/K
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
Ч 2 Ч ρb × 1/K / ρ norm
Kfactor = /4 × Nc × C / 1- β 4 × ε × d 2
× 2 / (ρb × 1/K)
*1
Qm or Qv_norm
=
Kfactor × ∆ρ × Tb/T × SP/SPb
Qv = Kfactor × ∆ρ × T/Tb × SPb/SP
*1
*1
*1 mark indicate user input.
*2 Kfactor must be calculated according to the specified flow unit.
Table 3.4 Symbol
No Symbol Description
1 Qm Mass Flow
2 Qv Volume Flow
3 Qv_norm Normal-Standard Volume Flow
4 Nc Unit convert factor
5 Kfactor Basic flow Calcuration factor
6 C Discharge Coefficient
7 ε Expansion Factor
8 β Diameter Ratio
9 d Diameter of orifice
10 ∆p Differential Pressure (Transmitter setting unit)
11 ρb Base Density on Tb, SPb condition
12 ρ norm Density on Normal, Standard condition
13 Tb Reference temperature (unit: K)
14 T Temperature (unit: K)
15 SPb Reference static pressure (unit: kPa abs)
16 SP Static Pressure (unit: kPa abs)
17 Temp K1 The density rate of change per temperature 1degC of a density base value (value which set 100%
to 1). For volume flow: set 0.
18 K Compressibility factor
Note 1. The flow unit is not automatically converted. Refer to IM 01C25R01-01E for Nc calculation.
Note 2. Kfactor, SPb, and Tb are calculated using the equipment setting unit (differential pressure, static pressure, and temperature).
Note 3. Total flow is calculated using the transmitter setting unit.