Thermo Scientific MIRAN 205B Series, Инструкция по эксплуатации

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5-1
Chapter 5
ANALYZE/START
To start the analysis, press
1
(Analyze/Start) from the Main Menu. The display presents
the Zero Menu if a zero has been taken for all of the current application wavelengths.
The date and time of the last zero and analyzer status are shown. To re-zero the analyzer,
press
1
. To continue with an analysis without taking a new zero value, press
ENTER
.
Note: If the analyzer has not been recently zeroed, the analyzer skips the Zero Menu
and displays the Analysis menu. See “To Begin Analysis” later in this chapter.
┌────────────────────────────────────────┐
│╒══ CURRENT APPLICATION ══╕ ZERO MENU │
││ │ Last zero: │
││ │ 04Jan01 13:30 │
││ │ │
││ METHANE: ---- ppm │ Status: Valid │
││ │ │
││ │ 1=New zero │
│└───────────────────────┘ Enter=Continue │
└────────────────────────────────────────┘
Zero Menu
TO ZERO THE ANALYZER
Caution:
1. When zeroing the analyzer, it is important to zero the unit in the area where the
analysis is to take place. This assures that the analyzer is zeroed with air (scrubbed by
the zero gas filter) at the same temperature and humidity as the sample to be analyzed.
2. However, for chemicals such as Butane, Carbon Dioxide, Carbon Monoxide, Ethane,
Methane, Nitrous Oxide, Propane, and Water Vapor, that can not be scrubbed by the zero
gas filter, it is important zero the unit in an area free of the chemical. For example, if
methane is being measured, zero the analyzer in a Methane free area. (Note: typical
atmospheric conditions are 2-3 ppm.) If the analyzer is zeroed in an area containing 7
ppm of Methane, the zero value is set at 7 ppm. All subsequent readings are then
referenced to the 7 ppm baseline value. Thus, if Methane rises to 15 ppm, the analyzer
displays a reading of 8 ppm; if it drops to 3 ppm, the display reads -4 ppm.
3. Thermo Fisher Scientific recommends that the zero gas filter be replaced after 30 zero
cycles.
4. The purging of the gas cell during the zero process requires five volumes of air (about
11 liters). The timing supplied in the analyzer's zero routine is ample to allow for this to
happen. However, if there is a restriction in flow that reduces the sample flow rate below
approximately 11 liters/minute or if the sample hose is lengthened, it is possible that the
cell may not be satisfactorily purged under these conditions. If so, repeat the zero
process until sufficient sample has been drawn through the zero filter.