Siemens SIPROCESS GA700 Operating Instructions Manual page 31

Measuring principle
The ULTRAMAT 7 can simultaneously measure up to 4 infrared-active measuring
components.
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.
An IR source
which is emitted in the beam splitter
divides the beam equally between the sample gas and reference gas compartments.
The chopper
relaxation of the receiver.
The reference beam passes through the reference chamber
chamber
concentration of the gas component to be measured.
The sample beam, by contrast, passes through the sample chamber
gas and enters the detector chamber
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
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.
Wall-mounted device
Operating Instructions, 05/2018, A5E31930403-06
①
with a temperature of approximately 600 °C generates infrared radiation
④
produces a periodic modulation of the infrared radiation, and thus enables
⑥
virtually unattenuated. The detector chamber
③
. The beam splitter
⑩
attenuated to various degrees. The degree of
⑨
. This sensor element converts the pressure difference
4.5 ULTRAMAT 7
③
acts as a filter chamber and
⑤
and enters the detector
⑥
is filled with a precisely defined
⑫
filled with sample
Description
31