Thermo Scientific Sarasota SG901, User Manual

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Thermo Fisher Scientific Sarasota SG901 User Guide
4-1
Chapter 4
Validation
Warning
Refer to the warnings section in the beginning of this manual.

A calibration tee is provided to facilitate purging of the density meter with
a known gas for calibration purposes. Alternatively, if the internal regulator
is to be checked, the inlet should be disconnected and the purging gas
supply connected in its place. In either case, the pressure measured at the
calibration tee with no flow should agree with the 4–20 mA signal from the
pressure transmitter.
To validate the system, it is necessary to either introduce a sample gas of
known characteristics into the system or take a sample of gas from the
system for laboratory analysis. If a sample is taken from the process stream
for laboratory analysis, it will be representative of the stream. If a test gas
mixture is introduced into the instrument, the mixture used should be
representative of the measured process stream. The reason for this follows.
The Sarasota SG901 system measures density, temperature, and pressure. It
then calculates density at reference conditions. The calculation of line
density and density at reference conditions require values of isentropic
exponent (specific heat at constant pressure / specific heat at constant
volume) and one of the following: Az and Bz (for the Thermo Scientific
Sarasota HME900) or critical temperature and critical pressure (for the
Thermo Scientific Sarasota CM515). These constants are calculated based
on the expected average gas constituents. If the validation gases are not
representative of the process gas, the constants will be in error and the
system may not operate to specification. If the validation gas is not
representative of the process, it may be required to change the gas constants
before validation and then return the constants to the operational values
after the test.
Refer to Figure 4–1 for the valves used in system validation.
General