Teledyne T100, Инструкция по эксплуатации, Страница: 92 / 404

Operating Instructions Teledyne ML - T100 UV Fluorescence SO2 Analyzer
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4.6.2. PHYSICAL RANGE VERSUS ANALOG OUTPUT REPORTING
RANGES
The entire measurement range of the T100 is 0 – 20,000 ppb, but many applications use
only a small part of the analyzer’s full measurement range. This creates two
performance challenges:
The width of the T100’s physical range can create data resolution problems for most
analog recording devices. For example, in an application where the expected
concentration of SO
2
is typically less than 500 ppb, the full scale of expected values is
only 0.25% of the instrument’s full 20,000 ppb measurement range. Unmodified, the
corresponding output signal would also be recorded across only 0.25% of the range of
the recording device.
The T100 solves this problem by allowing the user to select a scaled reporting range for
the analog outputs that only includes that portion of the physical range relevant to the
specific application. Only the reporting range of the analog outputs is scaled, the
physical range of the analyzer and the readings displayed on the front panel remain
unaltered.
Applications where low concentrations of SO
2
are measured require greater sensitivity
and resolution than typically necessary for measurements of higher concentrations.
The T100 solves this issue by using two hardware physical ranges that cover the
instrument’s entire 0 and 20,000 ppb measurement range: a 0 to 2,000 ppb physical
range for increased sensitivity and resolution when measuring very low SO
2
concentrations, and a 0 to 20,000 ppb physical range for measuring higher SO
2
concentrations.
The analyzer’s software automatically selects which physical range is in effect based on
the analog output reporting range selected by the user.
If the high end of the selected reporting range is

2,000 ppb. The low physical range is
selected.
If the high end of the selected reporting range is

2,001 ppb. The high physical range is
selected.
Once properly calibrated, the analyzer’s front panel display will accurately report
concentrations along the entire span of its 0 and 20,000 ppb physical range regardless of
which reporting range has been selected for the analog outputs and which physical range
is being used by the instrument’s software.