Download EJX910A and EJX930A Multivariable Transmitters

2-7
<2. About the EJX Multivariable Transmitter>
(6) Downloading flow parameter to a transmitter
Input Kfactor, Tb, SPb and TempK 1 to the
transmitter using either a Communication tool
or FlowNavigator.
Use the unit of “Kg/m3/degC” for TempK1
IMPORTANT
If either the setting of flow unit or differential
pressure unit is changed, Kfactor and Nc must
be recalculated.
Example 1: Calculation of Nc
(1) When flow unit is changed.
Nc= (Kg/s) /(Mass Flow unit in use)
Table 2.6
Example of Calculated Nc by Flow Unit
Flow unit
Calculation of Nc
kg/s
kg/h
lb/s
lb/h
Nc
(kg/s) / (kg/s) = (1kg/1s) / (1kg/1s)
(kg/s) / (kg/h) = (1kg/1s) / (1kg/3600s)
(kg/s) / (lb/s) = (1kg/1s) / (0.4535924kg/1s)
(kg/s) / (lb/h) = (1kg/1s) / (0.4535924kg/3600s)
1
3600
2.204623
7936.648
(2) When differential pressure unit is changed.
Nc = (Differential pressure unit)/(Pa)
Table 2.7
Example of Calculated Nc by Differential Pressure Unit
∆p unit
Calculation of Nc
Nc
Pa
(Pa) / (Pa) = (1Pa) / (1Pa)
1 =1
kPa
kPa/Pa = 1000Pa / 1Pa
1000 = 31.62278
inH2O@68degF
inH2O@68degF / Pa = 248.6406Pa / 1Pa
248.6406 = 15.76834
T0202.ai
(3) When both flow unit and differential pressure unit are changed.
Nc =(Kg/s)/(Mass Flow unit of use) × (Differential pressure unit of use)/(Pa)
Example 2: Calculation of Kfactor
Qm unit = kg/s, Differential pressure unit = kPa
Kfactor =
/4 × Nc × C/ 1− β4 × ε × d2 × 2×ρb×1/K
= 0.7853982 × 31.62278 × 0.6043 / 1−0.1296 × 0.984 × 0.031622 × 2×1.250380×1/1
= 0.02502868
0.02503
IM 01C25R01-01E