PCM-2 Manual.pdf - Voss Associates

Detector
Part No.
Detector Description
PCM-Z Serial No.
Effectivity
YPl1534560 Revised Detector Assembly, Long Serial No.'s 151 &
YPl1534561 Revised Detector Assembly, Medium
subsequent
YPl1534562
Revised Detector Assembly, Small
Detector Maintenance
Gas proportional detectors such as those used in PCM-2 require little maintenance
while in normal use in typical monitoring environments, other than keeping them
reasonably clean and supplied with counting gas. A detector with a clean,
contaminate-free mylar window will experience reduced background and will,
therefore, have a greater sensitivity to measured radiation within a given count
time. Since minimization of count times for measurement is of concern to almost
all users and because "dirty" often equates to "contaminated" in radiation
monitoring environments, PCM-2's detectors should be kept clean for maximally
efficent radiation measurements.
Detector Cleaning
Detector Protection
Particulates which settle on the mylar window of a detector can be "blown" away
with a clean (filtered), dry compressed air or gas source. Avoid using pressures
and/or nozzles which may puncture the detector's mylar face. Detectors that have
contaminated faces as a result of liquid or oil stains or residues should be removed
from the unit and carefully wiped clean with a soft wiper and alcohol. Again,
avoid any cleaning agent and/or practice which may puncture the delicate mylar
face of the detector.
The Medium sized probe located in the base of the PCM-2 is especially subject to
contamination from particulates released from the shoes of its users. For this
reason, special thin polypropelene film probe protectors are provided with the
standard PCM-2 unit. Ten (10) of these cardboard framed protectors are supplied
in a holder located in the unit's side door. They are installed over, and have bend
tabs for keeping them aligned atop the foot detector and can easily be removed,
cleaned or discarded, and replaced. Usage of these foot detector protectors will
preclude most detector punctures due to dirt or pebbles from shoes and will
greatly facilitate routine cleaning of the foot detector. An optional thin ploy or
mylar film dispenser roll is also available for the same protection and cleaning
purposes, offering an even greater degree of convenience for foot detector
servicing. Replacement film rolls and cardboard/film protectors are available
(Reference Sections 18, 19 and 20). The remaining detectors in the instrument
are each protected by a thin etched stainless steel screen. These screens serve to
prevent detector face punctures potntiaily caused by physical user interface with
PCM2.. MANI REV AI Arlil 1995 163