Yokogawa digitalYEWFLO (DY-FF) - Manual (Page 111)

<APPENDIX 6. Enhanced ARITHMETIC (AR) BLOCK>
A6-4
IM 01F06F00-01EN
A6.3 Computation Section
A6.3.1 Computing Equations
This subsection shows computing equations used
in the computation section:
1) Flow compensation (linear)
func = PV × f
f = (t_1 / t_2)
2) Flow compensation (square root)
func = PV × f
f = sqrt(t_1 / t_2 / t_3)
3) Flow compensation (approximate expression)
func = PV × f
f = sqrt(t_1 × t_2 × t_3 × t_3)
4) Quantity of heat calculation
func = PV × f
f = (t_1 - t_2)
5) Multiplication and division
func = PV × f
f = ((t_1 / t_2) + t_3)
6) Average calculation
func = (PV + t_1 + t_2 + t_3) / N
where N: number of inputs
7) Summation
func = PV + t_1 + t_2 + t_3
8) Polynomial computation
func = PV + t_1 2 + t_2 3 + t_3 4
9) HTG-level compensation
func = (PV - t_1) / (PV - t_2)
10) Polynomial computation
func = PV + GAIN_IN_1 × PV 2 + GAIN_IN_2 ×
PV 3 +GAIN_IN_3 × PV 4
* Precaution for computation
Division by “0”: If a value is divided by “0,”
the calculation result is
interpreted as 10
37 and,
depending with core, a plus
sign is added to it.
Negative square root: The square root of an
absolute value is extracted
and a minus sign is added to
it.
A6.3.2 Enhanced Computing Equations
32) Saturated steam (Temp): Saturated steam
density calculation (by temperature: based on
IAPWS-IF97)
func = PV x Correction Value
Correction Value: Saturated Steam density
calculated from t_1 (temp input).
Temperature range: 100 to 330°C
33) Saturated steam (Pressure): Saturated steam
density calculation (by pressure based on
IAPWS-IF97)
func = PV x Correction Value.
Correction Value: Saturated steam density
calculated from t_2 (Press. input).
Pressure range: 0.101417978 to
12.85752189 MPa
34) Superheat steam: Superheat steam density
calculation (based on IAPWS-IF97)
func = PV x Correction Value
Correction Value: Superheat steam density
calculated from t_1 (Temp. input) and t_2
(Press. input).
Temperature range: 100 to 330°C
Pressure range: 0.101417978 to 12.85752189
MPa
35) Gas temp pressure comp (Simple): Gas
temperature and pressure compensation
calculation. (Deviation factor: Fixed based on
Boyle-Charle's law.)
func = PV x Correction Value
Correction Value: Gas density ratio ( ρ
f
/ ρ
b
)
calculated from t_1 (Temp. input) and t_2
(Press. input), or, density at operating condition
(
ρ
f
).
36) Liquid temp comp (Simple): Liquid temperature
compensation calculation (based on API, JIS K
2249.)
func = PV x Correction Value
Correction Value: Liquid density at operating
condition calculated from t_1 (Temp. input).
37) Gas temp pressure comp (Detail): Gas
temperature and pressure compensation
calculation (approximating polynomial
calculation: 0 to 11).
func = PV x Correction Value
Correction Value: Gas density (Flow unit: Mass
fl ow rate) at operating condition calculated from
approximating polynomial calculation: 0 to 11,
or Density ratio (Flow unit: Volumetric fl ow rate
at normal condition) calculated from density at
normal condition.
38) Liquid temp comp (Detail): Liquid temperature
and pressure compensation calculation
(approximating polynomial calculation).
func = PV x Correction Value
Correction Value: Liquid density at operating
condition calculated from approximating
polynomial calculation: 0 to 3.