Quincy Compressor 50093-103 - Manual (Page 35)

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The fluid in the vacuum pump is the most critical
component. Most vacuum pump failures are the result
of contaminated or deteriorated fluid. Follow
recommended fluid change schedules in normal
applications (air) and watch closely the condition and
appearance of the fluid in chemical or harsh
applications. Use the Quincy fluid analysis program
to monitor the condition of the fluid. Leak check the
system by pumping down to the lowest attainable
pressure and then valve off the vacuum pump.
Monitor the pressure rise over a period of five or ten
minutes and record this rate of rise for future
reference. This value is a good toot to have if you
believe there are pump or system problems. Compare
new value with the original.
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Inlet filtration should be installed an every pump. The
potential for particulate contamination in rough
vacuum applications is significant. The particle
micron retention of the filter element should be smaller
than the smallest possible particle load. Also, the
inlet filter should be mounted in such a way as to
prevent particulate from falling into the inlet of the
vacuum pump during cleaning or changing of the
filter element.
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Be sure there is no back pressure on the exhaust line
of the vacuum pump. Vacuum pumps are not
specifically designed to compress exhaust gas above
atmospheric pressure, although they can be adapted
to do so with some modification. Significant back
pressure can overheat the pump and cause motor
overloading.
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When pumping condensable vapors and particulates,
more frequent fluid changes are required to maintain
pump life. Consult factory about types and styles of
filtration units.
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Maintain system seals on a regular basis. Tom 0-ring
and gaskets should be replaced immediately. All
flange faces should be free of dirt, lubricant, and
scratches.
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Do not use collapsible tubing to plumb the vacuum
system. Any restrictions in line diameter caused by
tube collapse will reduce available pumping capacity.
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In applications where auxiliary exhaust demisters are
used, back pressure in the reservoir should not
exceed 3 psig under normal operating conditions.
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Vacuum rated isolation valves should be used for
vacuum applications. Compressed air valves and
vacuum valves differ in their sealing characteristics
and compressed air valves may leak in vacuum
applications.
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In multiple pump installations, check valves should be
installed in the inlet piping. This will prevent fluid
from being drawn from an 'off' unit into an operating
unit. Check valves should be properly sized so as not
to "chatter" during operation. Spring loaded,
elastomer seated check valves are recommended.
These should be mounted in a horizontal flow
orientation.
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If there is a potential for liquids to be occasionally
drawn into the vacuum system, a receiver can and
should be used to separate these liquids from the
incoming air stream. In applications where there is
significant amounts of liquid, consult the factory.
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Vacuum gauge ports and gauges should be installed
in each log of central vacuum piping. This provides a
diagnostic tool for troubleshooting both the
application and any pump related problems.
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Continuous operation from atmospheric pressure to
10" HgV in not recommended for QSVI vacuum
pumps. In this vacuum range, there is not enough
differential pressure to scavenge the separated fluid
from the separator element back to the inlet valve.
This results in high fluid carryover. There are
modifications that can be made to the vacuum pump
to partially alleviate this condition. Please consult the
factory for details. Intermittent operation in this
vacuum range is acceptable.
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Any applications involving gases or vapors other
than air should be approved by Quincy prior to start-
up. These gases or vapors can react with the fluid or
materials of construction of the vacuum pump and
cause premature failures.
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Any vacuum pump placed in an application with inlet
gas stream temperatures above 120° should be
approved by Quincy prior to start-up.
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Quincy QSVI Rotary Screw Vacuum Pumps, with or
without enclosures, are designed for indoor
installation only.