Chapter 12
Maintaining an Electron Capture Detector
ECD Maintenance
222
Maintenance and Troubleshooting Manual
ECD Maintenance
The ECD, if properly used, has a good resistance against contamination thanks to
its unique internal geometry. However, some critical operating conditions may
give rise, in the long run, to contamination of the collecting electrode. This
contamination is highlighted by an excessive increase of the base frequency and a
baseline drift when the reference current or the pulse amplitude is changed. The
collecting electrode, in these cases, can be easily removed and cleaned without
disturbing the radioactive source.
If contamination of the whole cell is suspected, heat the ECD at the maximum
operating temperature with carrier and make-up gases flowing through the
detector (thermal cleaning). The decontamination process can be followed by
monitoring the base frequency. Initially the frequency value tends to increase to
very high values, and then it decreases to acceptable ones. If irreversible
contamination of the cell is suspected, please contact your local Thermo Fisher
Scientific Technical Service office for maintenance or replacement of the source,
whichever is necessary. Strictly follow the existing regulations for the transport of
radioactive material.
WARNING! The Electron Capture Detector (ECD) contains a
63
Ni beta-emitting radioactive
source of 370 MBq (10 mCi).
The
63
Ni radioisotope, electrically deposited as metal on a nickel foil, is inserted in a
cylindrical holder made of 6 mm thickness stainless steel. The holder is fixed to the
detector body, also made of stainless steel, in order to be totally inaccessible from
the outside.
The radioisotope
is not released by its support at temperatures lower than 450°C.
This temperature can never be reached by the detector, whose maximum operating
temperature is 400°C. A safety device prevents overheating.
In normal operating conditions, no dispersion of solid or gaseous radioactive
material is involved. This eliminates any risk of direct or secondary radiation.
For no reason should the detector be opened or handled by the user.
Any maintenance or service operations involving even partial disassembling of the
detector must be performed ONLY by Thermo Fisher Scientific Milan site or by a
laboratory specifically licensed to handle radioactive material.
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