Thermo Scientific 49i Instruction Manual page 55

Thermo Fisher Scientific
The O Background screen is used to perform a manual adjustment of the
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instruments zero background. Before performing a background adjustment,
allow the analyzer to sample zero air until stable readings are obtained.
The display shows the current O
background. The next line of the display shows the O
compensation that is stored in memory and is being used to correct the O
reading. The O background compensation is a value, expressed in the
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current gas units, that is subtracted from the O
reading that is displayed.
In the example below, the analyzer is displaying 4.4 ppb of O
sampling zero air. The O
the analyzer is not applying a zero background compensation. The question
mark is used to as a prompt to change the background compensation. In
this case the background compensation must be increased to 4.4 ppb in
order for the O reading to be at 0 ppb.
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To set the O reading in the example below to zero, use
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the O background compensation to 4.4 ppb. As the O
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compensation is increased, the O
this point, pressing
output or the stored O
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following both O reading and the O
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these are proposed changes as opposed to implemented changes. To escape
this screen without saving any changes, press
Calibration Factors menu or
to actually set the O
background compensation of 4.4 ppb. Then the question mark prompt
beside the O reading disappears.
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• In the Main Menu, choose Calibration Factors > O
• Use and
background value.
Press
• to save the new background.
reading. This reading is the O
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background compensation is 0.0 ppb. That is,
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concentration is decreased. Note that at
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and however, has no affect on the analog
background correction of 0.0 ppb. A question mark
background correction indicates that
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to return to the Run screen. Press
reading to 0 ppb and store the new
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to increment or decrement the proposed
Operation
Calibration Factors Menu
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background
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reading to produce the O
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while
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to increment
background
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to return to the
Background.
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Model 49i Instruction Manual
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