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Original documents
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● Specific noises can occur for several minutes after start-up.
1.1.2UV lamp service life
The Analyzer module DEFOR uses a UV lamp as light source. The UV lamp has a limited service life and probably needs to be replaced several times during the overall operating time.
Status messages of increasing importance are activated automatically when the light
intensity of the UV lamp weakens (→ p. 16 [7]).
● UV lamp service life → p. 26, §5.7
● Display of the operating hours with the PC software “SOPAS ET” → p. 14,
§4.1
1.2Application limitations
It is possible that another gas component contained in the sample gas can influence the
analysis of the desired measuring component (cross-sensitivity).
In such a case, a constant concentration of the “interfering gas” creates a constant deviation from the true measured value every time (constant characteristic curve offset). The
deviation varies accordingly when the interfering gas concentration fluctuates.
Important Information
● Cross-sensitivity against a certain gas is minimized automatically when the
DEFOR also measures the concentration of this gas.
● The cross-sensitivity can be minimized through computation in the control
unit when the interfering gas concentration is measured with a different
Analyzer module in the GMS800.
1.3Additional documentation/information
This document supplements the Operating Instructions for GMS800 gas analyzers. It
extends the “GMS800“ Operating Instructions with technical information on the DEFOR.
▸
Observe the delivered “GMS800” Operating Instructions.
The “GMS800” Operating Instructions also specify all further documents
belonging to the individual device.
NOTICE:
▸
Pay primary attention to any individual information provided.
The Analyzer module DEFOR uses the fact that some gases have a specific absorption
characteristic in the ultraviolet light range. For this purpose, UV light is radiated through the
sample gas. The concentration of a gas component in a gas mixture can be determined
through suitable selection of the light wavelength and selective absorption measurement.
The Analyzer module DEFOR can, in this way, analyze the concentration of the gases Cl
H
S, NO, NO2, NH3, SO2 and further gases.
2
The Analyzer module DEFOR can simultaneously measure up to 3 gas components.
Measuring method
● The Analyzer module DEFOR uses interference filter correlation (IFC) for most gas components. Measuring and reference radiation are created alternately by swiveling two different interference filters into the beam path (filter wheel [2a]).
● Gas filter correlation (UVRAS) is used for NO. This method creates the reference radiation by swiveling a gas filter filled with the relevant gas into the beam path (filter wheel
[2b]).
● Both measuring methods are combined for joint measurement of NO and other gases
(both filter wheels [2a]+[2b] are used).
● The physical state of the measuring system is captured and compensated using a reference beam path through a reference cuvette.
,
2
Analyzer module layout
– Beam source is a special UV gas discharge lamp (→ p. 8, Fig. 1 [1]) that emits both broad-
band as well as NO-specific radiation components.
– Thermostat-controlled filter wheel unit [2] keeps the optic filters at a constant tempera-
ture. This minimizes the influence of external temperature changes.
– Lenses [3][8], beam splitter [4] and mirror [5] direct the beam path.
– Sample gas flows through sample cuvette [6]. Reference cuvette [7] is either filled with
a neutral gas or has span gas flowing through (option).
– Detectors [9] capture the radiation intensity created with the various filters.
– Measurement signals are amplified electronically and digitally evaluated. The structure
symmetry compensates proportional and symmetric signal drifts in the best possible
way.
–The measuring system can be fitted with an adjustment unit ([10] → p. 10, § 2.2.1).
The specific properties of the desired measuring components and the desired
physical measuring range each demand an individual metrological concept for
the Analyzer module.