Emerson Micro Motion SGM Series - Page 41

Calculation aid for control pressure and associated measurement error (continued)Table 5-1:
Reference chamber or relief
valve
0.007 0.007 0.007 0.007
Total error (%)
Density range (minimum and maximum) Equation 5-1:

min
= P × 
Air
× SG
min

max
= P × 
Air
× SG
max
P
Control pressure (bar a)
ρ
Air
Density of clean dry air (1.2 kg/m
−3
approximately)
SG
min
Specific gravity minimum value
SG
min
Specific gravity maximum value
Temperature coefficient error Equation 5-2:
Error
DTC
=
DTC

max
× 100%/°C
DTC
Temperature coefficient for this meter
ρ
max
Maximum density value (kg/m
−3
)
Gas compressibility error Equation 5-3:
Error
Z
= ± 0.67 × TCC
GasRef
 TCC
GasSample
TCC
GasRef
For the reference gas, the coefficient that describes the relationship between
temperature and compressibility at control pressure. Refer to the International
Standard Gas Tables if required.
TCC
GasSample
For the sample gas, the coefficient that describes the relationship between
temperature and compressibility at control pressure. Refer to the International
Standard Gas Tables if required.
Velocity of Sound error Equation 5-4:
Error
VOS
=  0.0034 × SG
max
%/°C
SG
max
Maximum specific gravity value
Purging and calibration
Configuration and Use Manual 33