Thermo Scientific Sarasota SG901, User Manual

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Thermo Fisher Scientific Sarasota SG901 User Guide
5-1
Chapter 5
Calibration
Adjustment may be done in the field. However, it is important the
thermometry is known to be good before any other adjustment is made.
Adjustment is carried out if the applied reference (standard) does not
provide the expected output result. The allowable error of the system will
be the sum of the uncertainty of the supplied sample and the acceptable
error of the Sarasota SG901 system. For instance, if the acceptable error of
the system at the operating point is 0.2% and the uncertainty of the sample
is 0.5%, the acceptable error band is ± 0.7%.
There are two figures given for SG. Ideal SG is the ratio of the MW of the
sample and the MW of air and real SG. Real SG is the ratio of the densities
of the sample gas to the density of air at the same reference conditions.
The density meter measures density at actual conditions. To do this, we use
the following equation:
where
). P P ( PRESCO ) T T ( TEMPCO 0 T ' t
cal cal 0
− × + − × + =
The inputs to the equations are temperature, pressure, period (from the
density meter) and isentropic exponent (Cp/Cv). Where the gas matrix is
changing the average, isentropic exponent should be used. There is an error
associated with the isentropic exponent; however, a relatively large error in
isentropic exponent will only make a small error in density. The isentropic
exponent will usually be in the range of 1.2–1.4.
Field
Adjustments
SG Definition &
Calculation
,
' t
) ' t t (
K 2
' t
) ' t t (
' d
0
0
0
0
0 m






−
× + ×
−
× = ρ
.
t a
R VIBDIM
- 1 D0 =
d
2
0
















×
×
′
.
L P ISENEX
= a
m
2
1








ρ
× ×