Elster Instromet 2000 - Sarasota Density Transducer Inputs; Relative Density Transducer Input

Model 2000 Flow Computer Instruction Manual
2.0 GENERAL DESCRIPTION
Model 2000 issue 21 Page No
41
2.4.8.3. SARASOTA DENSITY TRANSDUCER INPUTS
The equations used for calculation of the Line density are as follows:-
1)
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−
×+×
−τ
×=ρ
'
0
'
0
'
0
'
0
'
0a
t
)tt(
K2
t
)t(
d
The value of line density is corrected for effects of temperature and pressure by the following equation.
2)
)Pp(escoPr)Tt(TempcoTt
cal1cal10
'
0
−×+−×+=
3)
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎝
⎛
τ×α
×
−×=
−
2
0
'
0
RVIBDEM
1Dd
4)
2/1
a
l
Lp
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎝
⎛
ρ
××κ
=α
−
If pl = 0 or d0’ < 0.8 D0 then d0’ = D0
Where
ρa : Line Density of Gas in kg/m3 Equation 1)
d0’ : VOS corrected cal constant of spool in Kg/m3 Equation 3)
α : Calculation intermediate Equation 4)
D0 : Calibration constant of spool in Kg/m3 DATA ENTRY
τ : Period of Densitometer in µS MEASURED
t’0 : Corrected Calibration constant of Spool in µS Equation 2)
K : Calibration constant of Spool in Kg/m3/°C DATA ENTRY
T0 : Calibration constant of Spool µS DATA ENTRY
Tempco : Temperature coefficient of spool in µS/°C DATA ENTRY
Presco : Pressure coefficient of spool in µS/BAR DATA ENTRY
VIBDEM : Characteristics of vibrating element in mm DATA ENTRY
κ : Isentropic exponent of Gas DATA ENTRY
t1 : Line Gas Temperature in °C MEASURED
pl : Line Gas pressure in Bar.a MEASURED
Tcal : Calibration Temperature of Densitometer 15°C DATA ENTRY
Pcal : Calibration Pressure of Densitometer 1.01325 Bara DATA ENTRY
L : Speed of Sound factor 100000pa/Bar DATA ENTRY
R : VOS correction to density 1000 DATA ENTRY
2.4.9. RELATIVE DENSITY TRANSDUCER INPUT
The relative density meter input to the Model 2000 is for a high frequency periodic type meter. It uses the same type of input
as would be configured for a turbine pulse inputs and this is of the form of one periodic input signal with the following
parameters.
Current input: 10mA.
Frequency range: Up to 5kHz.
The basic equations used for calculation of the Relative density from this type of input is as follows:-
1)
)T10K(Kd
26
20b
××+=
−
2)
bbn
dair ×ρ=ρ