PORTABLE INERTNESS ANALYZER
The inertness analyzer (fig. 6-17) is a portable,
electrical instrument used to indicate the presence of
inert gas and combustible vapors in the atmosphere
in voids surrounding the gasoline storage tanks and
double-wall piping when the service system is being
purged.
Components and Functions
The instrument is contained in a case with a
carrying handle. On the front of the box are the
controls and indicating dial. An ON-OFF switch
controls electrical power to the analyzer. A
milliammeter indicates the analyzer current in
milliamps. The galvanometers indicates presence of
inert gas in percentage of inertness.
The unit has three potentiometers: the current
potentiometer that is used to set the analyzer current
to 150 milliamps: the sensitivity potentiometer that is
used to calibrate the analyzer: and the zero
potentiometer that is used to make a final adjustment
to zero the galvanometer, if necessary.
Figure 6-17.—Portable inertness analyzer.
A sample dryer (which has only a bottom hose
connection) is filled with calcium chloride that
absorbs moisture from the sample, and a vapor
absorber (which has upper and lower hose
connections) is filled with activated carbon that
absorbs fuel vapors from the sample. An aspirator
bulb and hoses are used to pump samples through the
analyzer. The unit is powered by two 6V dc batteries.
Operation
Before using the instrument to analyze an
enclosure, the unit must be prepared in normal room
air. The current must be adjusted, and the analyzer
must be purged and zeroed.
To prepare the analyzer for use, turn the unit
ON. adjust the current to 150 milliamps, and allow 2
minutes for the analyzer to reach operating
temperature. Make sure the aspirator discharge is
connected to the analyzer. Then use the following
steps:
1. Connect the aspirator bulb and hoses to the
inlet of the sample dryer.
2. Aspirate air through the analyzer until the
galvanometers needle comes to rest.
3. If necessary, set the galvanometers needle to
zero using the zero adjustment.
To analyze enclosures containing air and inert
gas, use the following steps:
1. Connect the aspirator bulb and hose between
the sampling outlet of the enclosure to be tested and
the inlet of the sample dryer.
2. Operate the aspirator bulb until the
galvanometers needle comes to rest.
3. Note the reading.
To analyze enclosures containing air, inert gas
and fuel vapors, use the following steps:
1. Connect the aspirator bulb and hose between
the sampling outlet of the enclosure to be tested and
the inlet (bottom) of the vapor absorber.
2. Connect the jumper hose between the outlet
(top) of the vapor absorber and the inlet of the sample
dryer.
3. Operate the aspirator bulb until the
galvanometers needle comes to rest.
4. Note the reading. If this reading is not the same
as the reading when testing for only air and inert gas,
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