HP 5890 Series II Plus Reference Manual page 136

Detector Systems
Electron capture detector (ECD)
WARNING In the extremely unlikely event that both the oven and the ECD heated
zone should go into thermal runaway (maximum, uncontrolled heating
in excess of 400 C) at the same time, and that the ECD remains
exposed to this condition for more than 12 hours, the following must be
done:
It is unlikely, even in this very unusual situation, that radioactive
material will escape the cell. Permanent damage to the
within the cell is possible, however, so the cell must be returned for
exchange.
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After turning off main power and allowing the instrument to cool,
cap ECD inlet and exhaust vent openings. Wear disposable plastic
gloves and observe normal safety precautions.
Return the cell for exchange, following directions included with the
form General License Certification (HP Pub. No. 43•5954•7621).
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Ni plating