Yokogawa EJX115A - Manual (Page 27)

<5. Parameter Setting>
5-7
IM 01C25T04-01EN
<5> To confirm entered coordinate.
• Procedure to call up the display
DTM [Device] → Configuration →
Characterization → Table Data
EDD [Device] → Characterization →
Linearization Table
5.3.4 Calculate Coefficient (For flow rate
calculation)
Calculate Coefficient is constant mainly for
calculation of flow rate output signal. Follow
below procedure to set the Calculate Coefficient.
Sensor Transducer Block Target Mode needs to
be changed to Out of Service (O/S) before enters
Calculate Coefficient.
DTM Input → Target Mode
EDD Input → Sensor Transducer Block →
Target Mode
• Procedure to call up the display
DTM, EDD Input → Sensor Transducer Block →
Calculated Value → Calculate Coefficient
There are two methods for the calculation of the
Calculate Coefficient (below Kfactor).
Method 1: Calculating the Kfactor by flow
parameters
Method 2: Calculating the Kfactor by means of the
flow condition
Method 1. Calculating the Kfactor by flow
parameters.
<1> Selection of the flow equation
Select the desired operational expression
according to the fluid type and the flow unit
category shown in Table 5.2.
<2> Confirming the unit
The unit to be used in this calculation is as
follows:
Differential pressure: Pa
Static Pressure: kPa abs
Temperature: K
The dimension of the pressure unit Pa are
M•L -1 •S -2
Where M: mass (Kg)
L: Length (m)
S: Time (second)
<3> Preparation of flow parameters for Kfactor
calculation
Each parameter must be expressed in the
following units.
d: m,
ρb and ρnorm: Kg/m 3
C, β, ε and K has no dimensions
<4> Calculation of the unit conversion coefficient Nc
The flow rate value does not change
automatically when a flow unit parameter is set
for the transmitter, and is always output as Kg/s
(mass flow). M 3 /s (volume flow), Nm 3 /s (Normal
volume flow.)
In order to obtain a value in your designated
unit, it is necessary to set Nc.
Nc is a conversion coefficient for the flow and
DP unit that is designated to be used.
<5> Selection of the Kfactor equation and
calculation Select the Kfactor expression
according to the unit category shown in Table
5.2.
Calculate the Kfactor using the parameters and
the expression.
<6> Enter Kfactor as shown in beginning of this
section.
IMPORTANT
If either the setting of flow unit or differential
pressure unit is changed, Kfactor and Nc must
be recalculated.
Table 5.2 Flow Operational Expression
T0501.ai
Flow unit Category Kfactor Flow
Normal · Standard
Volume Flow
Volume Flow
Mass Flow Kfactor = /4×Nc×C/ 1–β 4 ×ε×d 2 × 2×ρb
Kfactor = /4×Nc×C/ 1–β 4 ×ε×d 2 × 2×ρb /ρnorm
Kfactor = /4×Nc×C/ 1–β 4 ×ε×d 2 × 2/ρb
Qm, Qv or Qv_norm = Kfactor × ∆P