8 A-96.250.811 / 091017
AMI Silitrace
Product Description
2. Product Description
2.1. Description of the System
Application
Range
The AMI Silitrace is a complete monitoring system for the automatic,
continuous measurement of the dissolved silica content in water
steam cycles or demineralizer plants.
Photometrical
Detection of
Silica
The determination of silica is done by the photometric analysis of
molybdate blue at 815 nm.
Silica and ortho-phosphates react at low pH with ammonium mo-
lybdate to the yellow colored molybdosilic acid respectively molyb-
dophosphoric acid. The molybdophosphoric acid is destroyed with
oxalic acid before the molybdosilic acid is reduced with iron-(II)-am-
monium-sulfate to the heteropolyblue complex.
Especially the reaction speed of the first reaction step to the molyb-
dosilic acid is relatively slow. It is the most time consuming part of
the whole reaction. As the reaction speed increases with increasing
temperature, it is time saving to heat up the sample. The AMI Sili-
trace therefore uses a thermostatic reaction chamber with a con-
stant temperature of 45 °C.
At 45 °C the complete reaction only needs 150 s (2.5 min). Be-
cause the reaction time plays an important role in the color devel-
opment, the pump speed is adjusted constantly. Due to the
automatic heating and reaction time regulation a very high preci-
sion is achieved.
Instrument
variants
The AMI Silitrace is available in two variants:
AMI Silitrace
AMI Silitrace Dual-Stream
Both instruments are identical except that the AMI Silitrace Dual-
Stream includes a channel selector valve.
Sample
Sequencer
If measurement of more than two sample streams is required, the
AMI Silitrace can be connected to a Sample Sequencer, which al-
lows to measure up to six sample streams.
Automatic
calibration and
verification
A calibration, verification or zero measurement can be performed
automatically according to a programmed time schedule or started
manually.
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