MOISTURE ANALYZER0 pages

Bulletin
TD 967

HydroTracer Moisture Analyzer
Tinius Olsen introduces a new kind of moisture analyser that will
appeal to all manufacturers who have moisture concerns. This
new tester is less expensive, just as swift to generate a result,
and as accurate as comparable heat and weigh or microwave
technique based testers. The patented method of the HydroTracer determines the absolute water content where the mass of the
water is measured within the reactor.
Operation is just as simple. The sample is weighed and filled
into the sample tray of the Hydrotracer which is then placed in
the tester’s heating chamber. The heater warms the sample to a
temperature chosen by the operator and water within the sample
evaporates. The heating chamber is connected with the cooled
upper reactor chamber of the HydroTracer – this is where the
calcium hydride reagent is placed. The volatile water rises to the
upper reactor chamber and when the humid air flows over the
reagent, the gaseous water reacts with calcium hydride according the following equation:
t

CaH2 + 2 H2O → Ca(OH)2 + 2 H2

The cooled, dry air returns to the lower heating chamber and the
process continues. The circulation of air through the HydroTracer
is supported by natural convection which is promoted by the
unique design of the HydroTracer; even hygroscopic materials
are completely dried with the HydroTracer. The final concentration of hydrogen in the reactor is proportional to the water content of the sample before the measurement. The whole opera-

Fig 1. HydroTracer with all the accessories.

tion process is controlled by pc based software and the results
calculated for the operator.
The ambient air also contributes water to the reactor atmosphere,
so, to achieve accurate results the ambient air humidity and density needs to be determined and “removed from the equation”.
Integrated sensors in the reactor do this. The concentration of
hydrogen is measured by thermal conductivity sensors.
Chemical Reactions And The Reagent
Calcium hydride reacts with water to form calcium hydroxide
(also called hydrated lime, or agricultural hydrate), which is a
weak base and quite harmless; it also does not require any special disposal techniques. The small amount of reagent needed for
the test means that the amount of hydrogen produced is small
and subsequently does not pose any operational concerns.

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Sample in removeable heating tray
Hot humid gas rises into the reactor chamber
Reagent absirds water vapour and releases hydrogen gas
Sensors measure the concentration of hydrogen gas
Cooled, dry gas descends and can absorb more water vapour.

Fig 2. Diagram showing principle of
operation of HydroTracer.