Liquid Controls SP4000 - Manual (Page 101)

SP4000 Flow Computer
98
Pressure Input:
General Case
Pf = [% input span • (Pres full scale - Pres low scale ] + Pres low scale
Gauge Case
Pf = Pf + Barometric
Manual Case or In Event of Fault
Pf = Pressure Default Value
Temperature Computation:
General Case
Tf = [% input span • (Temp full scale - Temp low scale ] + Temp low scale
RTD Case
Tf = f ( measured input resistance)
Manual Case or In Event of Fault
Tf = Temperature Default Value
Delta Temp Case
Delta Temp = T2 - T1 Flowmeter location = cold
Delta Temp = T1 - T2 Flowmeter location = hot
Density Computation:
Water Case
density_water = density (Tf)
Liquid Case
density = reference density • ( 1 - Therm.Exp.Coef. •( Tf - T
ref
)) 2
Steam Case
density = 1/ specific volume(Tf, Pf)
Gas Case
Pf (T
ref
+ 273.15) Z
ref
density = reference density • • •
P
ref
(Tf + 273.15) Zf
NOTE: For Natural Gas:
is determined by NX-19 when this selection is supplied and
selected.
NOTE: Therm.Exp.Coef is (x 10 -6 )
7.3.2
Pressure
Computation
7.3.3
Temperature
Computation
7.3.4
Density/Viscosity
Computation
Z
ref
Zf