Figure F-3: Gas compressibility error
Error
Z
= ± 0.67 x T CC
GasRef
− TCC
GasSample
TCC
Gas
Ref
For the reference gas, the coefficient that describes the relationship between temperature and
compressibility at reference chamber pressure. Refer to the international gas standard tables,
such as ISO12213 if required.
TCC
Gas
Sample
For the sample gas, the coefficient that describes the relationship between temperature and
compressibility at reference chamber pressure. Refer to the international standard gas tables,
such as ISO12213 if required.
Figure F-4: Velocity of sound error
Error
VOS
= − 0.0034 x SG
Max
% /°C
SG
max
Maximum specific gravity value
F.1 Calculation aid and examples
Blank calculation form
Type of gas:
Specific gravity range: ______ to ______
SGM temp coefficient (kg/m
3
/°C):
Reference chamber pressure at 20 °C:
18 psia
(1.24 bara)
30 psia (2 bara)
60 psia (4 bara)
100 psia (7 bara)
Density range at 20 °C: in kg/m
3
: ______ to ______ ______ to ______ ______ to ______ ______ to ______
Measurement
error
Temp coefficient
error:
Gas
compressibility of
sample gas:
Velocity of sound
in sample gas:
Reference
chamber or relief
valve:
Total error (%):
(1)
% of full-scale specific gravity / C
Calculate measurement errors using reference chamber pressure
Configuration and Use Manual
March 2021
MMI-20020954
188
Micro Motion Gas Specific Gravity Meters (SGM)
