Thermo Scientific MIRAN 205B Series, Инструкция по эксплуатации

Страница: 180 / 214

Appendix C Scan/Calibration Procedure
C-6
D. ANALYZE THE SPECTRUM
1. In PCIP, highlight the file containing the logged scan data and press
"F2=Edit". The file should contains a header and two columns. The first
column contains the wavelength data and the second column is the
corresponding absorbance.
2. The wavelength typically chosen corresponds to the maximum absorbance in
the scanned range. Record this wavelength.
3. At this point data may be imported into a program capable of graphing the
data (e.g., ThermoMatch, Excel, Lotus, MatLab). This will visually represent
the raw spectra and aid in the selection of the best spectral peak.
E. CREATE A NEW SINGLE GAS OR MULTI-GAS LIBRARY
APPLICATION
In many cases, more than one gas exists in an atmosphere. It may be necessary to
measure these gases simultaneously. One reason for this is that several spectra may
overlap at the analyzing wavelengths, resulting in interference that requires
compensation. Another reason for simultaneous measurement is to expedite the
measurement process.
In order to determine whether interference exists it is necessary to compare the infrared
spectra of the gases. Spectra may be obtained from internet web sites such as the NIST
Chemistry Webbook (
http://webbook.nist.gov/chemistry/) . It will be necessary to print
out the appropriate spectra and overlay them to determine if interference exists.
Reference books such as Brian Thompson’s “Hazardous Gases and Vapors: Infrared
Spectra and Physical Constants”, Beckman Instruments, Inc. Industrial Technical Report
TR-595, 1974 can also be used. Alternately, the SapphIRe can be used to generate spectra
of known gases.
The following procedure is used to create a library application once it has been
determined whether a single or multi-gas application is appropriate.
Note:
Many of the steps used to create a single or multi-gas library are identical. They
are clearly identified where they differ.
1. From the Main Menu select "2=Change gas".
2. From Select Applic menu select "Enter=Other". If no application has been
previously selected, this step is omitted and the instrument skips to step 3.
3. From Applic menu select "2=Single gas" or "3=Multi-gas"
4. Choose the first empty position number (e.g., “2=<empty 2>”). The analyzer
will beep and an error message will state that an application processing error
has occurred and the application is invalid. Ignore this message and select
"Enter=Continue".