PCM-2 Manual.pdf - Voss Associates

Section 9
Maintenance
Preventative Maintenance
Routine Maintenance
The PCM-2 instrument should be kept clean and dry. Dust should not be allowed
to accumulate on printed circuit boards or other electrical components within the
unit's internal electronics enclosures. Dust accumulations can result in noise
problems or high voltage power supply arcing. It is therefore important that the
electronics enclosure, CRT enclosure and ceiling cover panels are replaced and
securely fastened subsequent to accessing the electronics or detectors for servicing
or system setup.
The P-lO counting gas supply should be replaced when the its supply cylinder(s)
pressure is unable to provide at least 5 psi at the regulated low pressure output. If
the instrument is supported with an optional gas bottle enclosure, routine gas
pressure checks can be made by viewing the pressure gages on the supply
cylinders through the enclosure's clear lexan window. A single size lA (1.54 ft')
gas cylinder will support a standard PCM-2 instrument in good condition (i.e. no
punctured detectors) and with a normal operational gas now rate for
approximately 32 days at a nominal gas flow rate of 200cc/min. The same
instrument equipped with an optional gas manager will consume approximately
only 15-20 % of the counting gas of a standard, continuously flowing system,
thereby operating for approximately 160 days 011 a lA size cylinder at the same
200cc/min nominal gas flow rate.
The gas supply plumbing harness for the instrument incorporates an in-line filter
for gross particulate and moisture removal from the gas prior to entering the
detectors. Alrhough this filter, located in the lower electronics enclosure, is not
likely to become clogged in normal usage, it should be replaced if gas t10ws
become inhibited or if a bad or dirty supply of gas is suspected to have been used.
The reuseable/disposeable protective cardboard and polypropylene film covers for
the foot probe (of which spares arelocated in the internal pocket on the side door
of the unit) should be routinely cleaned or replaced to avoid accumulations of
particulate contamination on the probe face. If the optional protective film
dispenser is installed, this routine procedure is to advance a fresh width of film
over the detector face from the supply roll. This procedure may need to be
PCM2.MANI REV AI April 1995 9-1