2002 by ELTRA GmbH Germany – January 2002 – Service Manual OH 900 / ON 900 / ONH 2000
1.6-1
1.6
1.6
High blank value
It is impossible to avoid blank values, because oxygen and nitrogen are contents of the
air. But this blank value should not be higher than 5 to 10ppm.
Otherwise try the following :
Increase the flow rates to 40 / 70 l/h
Fasten the electrodes
Clean the furnace
Use a gas precleaning furnace, filled with copper
Connect a computer to watch the blank value peak and start an analysis without any
sample.
In some cases a small air volume remains in the threads under the lower electrode.
Screw the lower electrode out and fill a small amount graphite powder in. Screw the
electrode in. Repeat this procedure until it needs some force to screw the electrode
complete in.
If the base line of the detectors is unstable due to insufficient mains voltage
( less than 200V AC ), connect a voltage stabilizer ( see 3.14 ).
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