Instruction manual

NGA 2000 MLT Hardware
MEASURING PRINCIPLE
2 - 6
Emerson Process Management GmbH & Co. OHG
Instruction Manual
90002929
07/2006
2.2 UV Measurement
The absorption measurement in the UV spectral range is based on the same principle as the IR
measurement (Fig. 2-1).
A glow-discharge lamp [2] is used as radiation source.
The UV radiation passes through the chopper [3] and a filter cell [6] into the dual-section analysis
cell [7].
A second filter cell [6] is installed after the analysis cell. The photodetector [13], which follows,
converts the pulsating radiation intensities from measuring [8] and reference side [9] of the analysis
cell into electrical voltages.
As the glow-discharge lamp needs a specific and as constant as possible temperature, the UV
lamp is thermostatted to about 55 °C for MLT 1 or the lamp is built-in into a thermostatted ambiente
(MLT 2/3/4).
UV MEASUREMENT