PCM-2 Manual.pdf - Voss Associates

the detector panels (i.e. sharp or protruding clothing, pens, pencils, badges,
jewelry, etc.). If any detector becomes punctured, or otherwise damaged to the
point of failure, it can easily be removed and replaced with a spare detector.
Detector Replacement
Special Considerations
The PCM-2 has been designed for quick and easy removal and replacement of its
detectors. Velcro® cinch straps retain the detectors in their respective panels in
the instrument and quick-connect self-sealing fittings attach their gas plumbing
harnesses. Therefore, no tools are required for detector removal and installation.
A spare purged (air evacuated/P-lO gas filled) probe can thereby replace a
damaged detector in minutes, preventing lengthy instrument downtime while a
detector is repaired. An optional set of spare, continuously purging and internally
mounted detectors is available to support such detector replacement requirements,
(Reference Options Section).
PCM-2 detectors are quite sensitive to contamination due to outgassing of various
substances which can come in contact with internal surfaces of the probe chamber
and/or those of its gas delivery components. When this happens the subject
detector(s) can experience a notable decrease in efficiency characterized by low
beta background values. This "poisoning" of the detector chamber can be caused
by its exposure IO any organic solvents which are present in substances such as
(but not limited to) adhesives, sealants and lubricants. This is especially true of
RTV (silicone) adhesives. Avoid using these types of substances in areas or on
components which are in direct contact with or carry counting gas to the internal
surfaces of the detector assemblies.
Detector Rebuilding
PCM-2 detectors have been designed to be field-repairable. Often during the
course of normal instrument usage, one or more detectors may go out of service
due to mylar face punctures, anode wire breakage and/or other internal electrical
failure(s). In the event of such detector(s) failure, repair becomes necessary.
Eberline has developed specific processes for the repair or complete rebuild and
testing of PCM-2 probes which vary depending on the configuration of detector
assembly involved. Identification of the type of detector assembly to be rebuilt is
of primary consideration in the rebuilding effort (Reference the detector
configuration table above in this section).
Document llOOO-A308, PCM-2 Revised Detector Assembly Procedure defines the
detailed process steps for the complete assembly manufacture of the revised design
detectors. Document 10429-A525, PCM-2 Detector High Voltage and Leak Test
Procedure defines those processes required to properly test the probes when
assembled. This procedure appears in Appendix B and supplements the detector
assembly drawings 11534-D560, 11534-D561 and 11534-D562 for the revised
probes.
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