Reference Gas Monitoring - Siemens SIPROCESS GA700 Operating Instructions Manual
Continuous gas analysis, rack-mounted device
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- Operating manual (306 pages) ,
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Measuring principle
The measurements are based on the molecular-specific absorption of infrared radiation bands
(absorption bands). ULTRAMAT 7 analyzer modules use a spectral range which includes
wavelengths of 2 to 9 µm. Although the absorbing wavelengths are characteristic of individual
gases, they may partially overlap. This results in cross-sensitivities which are reduced to a
minimum by the following measures:
● Beam splitter (gas filter)
● Double-layer detector, each gas compartment with adjustable weighting between the first
and second detector layer
● Application-specific factory-fitted interference filter
How it works
ULTRAMAT 7 analyzer modules operate according to the infrared push-pull chopped radiation
principle and are equipped with a double-layer detector.
A source with a temperature of approximately 600 °C generates infrared radiation which is
emitted in the beam splitter. The beam splitter acts as a filter chamber and divides the beam
equally between the sample gas and reference gas compartments.
The chopper produces a periodic modulation of the infrared radiation, and thus enables
relaxation of the detector.
The reference beam passes through the reference chamber and enters the detector chamber
virtually unattenuated. The detector chamber is filled with a precisely defined concentration of
the gas component to be measured. The sample beam, in contrast, passes through the sample
chamber filled with sample gas and enters the detector chamber attenuated to various degrees.
The degree of attenuation depends on the respective sample gas concentration.
The detector is designed as a double-layer detector. The detector layer at the source end
serves primarily to absorb the middle of the band. The band edges, however, are absorbed
equally by both of the layers.
The detector layers at both compartments of the detector are pneumatically connected to each
other via a microflow sensor. This sensor element converts the pressure difference in the
detector into an electrical signal.
The weighting between the first and second detector layer is preset at the factory depending
on the application. This minimizes the effect of interfering components.
To ensure the long-term stability of the measured value, the ULTRAMAT 7 analyzer module
supports the predictive self-diagnostics of the analyzer. This function enables you to plan
maintenance measures in a timely manner.
3.5.2
Reference gas monitoring
Only the device versions of the ULTRAMAT 7 with a flow-type reference end are equipped
with reference gas connections. Connection fittings with a pipe diameter of 6 mm are provided.
Select a suitable material for the reference gas for gas inlet and gas outlet.
A flow of approx. 0.5 l/min is recommended. Values from 0.1 l/min to 1.5 l/min are possible.
Rack-mounted device
Operating Instructions, 05/2015, A5E31874006-03
Description
3.5 ULTRAMAT 7
35
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