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AMI has developed a reliable
and compact portable Sample
Pump Module that addresses a wide
range of previously impossible vacuum applications.
One unique aspect of our breakthrough
pump module is that it uses a very specialized
diaphragm that diffuses less than 0.5ppm
of oxygen while drawing from pressures as
low as 14"Hg. This allows the operator
to draw from a partial vacuum and then push
the sample gas through the trace oxygen
analyzer, allowing the sensor in the analyzer
to operate at atmospheric pressure. Electrochemical
oxygen sensors must operate at or very close
to atmospheric pressure for accurate and
stable operation.
Prior sample pump technologies
used various types of diaphragm materials,
which either allowed too much oxygen to
diffuse, or alternatively developed small
leaks allowing air to be drawn into the
system. In either case, the measured trace
oxygen values would be misleadingly high.
Historically vacuum applications
were limited to positioning pump or eductors
downstream of the trace oxygen analyzer.
This would draw sample gas through the analyzer
then through the pump and exhaust it under
pressure to the atmosphere.
This of course directly exposes
the oxygen sensor to the varying negative
pressures at which the pipeline or application
operates, causing erroneously low readings,
drift and sensor damage.
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The AMI portable Sample Pump
Module incorporates a 12VDC long life brushless
motor and pump designed to last for over
20,000 continuous hours and incorporates
state-of-the-art electronics that meet the
safety requirements of Class 1, Div. 2 Group
C and D.
The NiCad batteries will operate
for 4 hours on a full charge if run continuously
and longer if operated intermittently.
The pump is capable of handling
a wide range of inlet pressures from 14"Hg.
to +10psig while maintaining a constant
10psig output pressure. Lastly we use a
check valve between the inlet and outlet
of the pump to prevent diaphragm damage
in the event the inlet or outlet ports become
restricted.
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