ELTRA CS-580A, Manual

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As different samples can contain different amounts of moisture, it is hard to give a precise
number of analyses that can be made before the content of the reagent tubes should be
replaced.
A regular check of the reagents is essential to secure a failure free operation of the analyzer.
The moisture stems from the combustion and has two sources. One source is the water content
of the sample. By drying the sample in a furnace at about 80 °C, the moisture content can be
reduced. The sample is laid in a fairly flat bowl and should be spread as thin as possible. The
drying process takes some hours.
The second source is the hydrogen content of the sample itself, available in various hydrogen
compounds.
The following chemicals are used
Magnesium perchlorate (Anhydrone) as moisture absorber
Sodium hydroxide as CO2 absorber
The reagent tubes have to be replaced when they are saturated. If the absorber particles do not
move when tapping on the glass, it is a sign that the magnesium perchlorate is saturated. It is
essential to change the absorber before it is completely solid. The sodium hydroxide changes
its color after being saturated (it turns to light grey).
Please refer to chapter
front panel illustration to identify the glass tubes on the analyzer.
Before filling the reagents into the glass tubes, their lower end has to be stuffed using glass
wool. One should pay attention that the layer of glass wool should be pressed only as strongly
as necessary, otherwise the flow of gas could be choked. Under no conditions the amount of
glass wool should be less than that given in the following schematics, as fine particles of
magnesium perchlorate could penetrate the glass wool and accumulate at the bottom of the
tube blocking the fitting and building deposits in tubes and in the Infrared cell paths.
At both ends of the glass tube, you should leave sufficient space for the gas connections to be
fitted. The free spaces at the tube ends serve as sealing areas. They must be cleaned and
greased after filling.
Both, the O-rings as well as the sealing areas of the tube are to be greased with high vacuum
silicon grease. This enables easy reassembling as well as later removing. In addition, greasing
improves the sealing of the tubes to the O-rings. Only the upper end of the right hand glass tube
(moisture trap) and the corresponding O-ring should not be greased.
Make sure that the O-rings are completely sealed around the glass tubes!