Physical and analog output ranges, Reporting range modes – Teledyne 9110EH - Nitrogen Oxides Analyzer User Manual

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Model 9110EH Instruction Manual Operating Instructions

A2 OUTPUT (NO): Output Signal = 4-20 mA (with current loop option)

A3 OUTPUT(NO

): Output Signal = 0 - 1 V

Output A4 can be set by the user to report one of many of the parameters accessible

through the keys of the unit’s SAMPLE mode display. A4 is not available for the
current loop option.

6.5.1. Physical and Analog Output Ranges

Functionally, the Model 9110EH NO

analyzer has two physical ranges for determining NO

, NO

and NO

concentrations. The difference between the two physical ranges is the resolution of

the output signals from the preamplifier board. Internally, the analyzer’s signal resolution is
about 16-bit or 72000 counts per 5 V PMT signal. The low range spans 0 to 2000 ppb NO

(2000 ppb = 5 V) whereas the high range spans 0-20000 ppb NO

(20000 ppb = 5 V). Both

ranges need to be calibrated independently to the same span gases in order to allow

switching back and forth between high and low ranges. Once properly calibrated, the
analyzer’s front panel will accurately report concentrations between 0 and 20000 ppb,

regardless of the selected analog range. To switch between physical ranges, the user has to
specify an appropriate analog output range from the front panel. Any analog range between
0 and 2000 ppb will cause the analyzer to remain in the low physical range. Any upper

analog range limit between 2001 and 20000 ppb will cause the instrument to operate in its
high physical range.

For applications using chart recorders or other analog recording devices, such a wide range
can usually not be resolved on the output. For example, in an application where the

expected concentrations of NO, NO

and NO

are typically less than 500 ppb, the full scale

of expected values is only 0.25% of the instrument’s 20000 ppb physical range. The

corresponding output signal would then only be recorded across 0.25% of the range of the
recording device.

The M200E solves this problem by allowing the user to select a reporting range for the

analog outputs that only includes that portion of the physical range that covers the specific
application. Note that only the reporting range of the analog outputs is scaled, the physical

ranges of the analyzer remain unaltered with the exception of the 2000/2001 ppb split. This
increases the reliability and accuracy of the analyzer by avoiding additional gain-amplifica-

tion circuitry. If properly calibrated, both the iDAS values and the concentration values on
the front panel are also unaffected by any change in analog output ranges.

6.5.2. Reporting Range Modes

The M9110EH provides three analog output range modes to choose from.

• Single range mode (SNGL) sets all measured gases to the same output reporting

range.

• Independent range mode (IND) allows the reporting ranges for all gases to be

different.

• Automatic range mode (AUTO) gives the analyzer the ability to report data through

a low range and high range by automatically switching into the appropriate range as
the concentrations change.

Only one of the above range modes can be active at any time. To select output range types,
use the following key sequences.

M9110EH Rev 0