PORTABLE INERTNESS ANALYZER

Adjusting the inert-gas-pressure regulating valve

Aviation Boatswains Mate F - Aviation theories and other practices
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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, 6-18

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