Environmental Technologies Group, Inc.

Peter C Stroosnyder

Charles H Ward, Ii

Stephen D Kubicsko

Kenneth B Regiec

In an apparatus for an air sample analysis, employing a dual polarity Ion Mobility Spectrometer (IMS), a method for stabilizing equilibrium conditions associated with the switching of the electric fields in the IMS cell comprises the steps of modulating a duty cycle of the electric field at the shutter grid located between the reactor region and the drift region of the IMS cell. During the switching of the electric fields at the cell, the open time of the duty cycle of the electric field at the shutter grid is extended. After the background polarity has been switched to the opposite polarity, the open time is returned to its normal value.

Method and an apparatus for an air sample analysis

In an apparatus for detecting alarm molecules, residual alarm molecules are automatically removed during a clear-down mode before a subsequent air sample is to be introduced. The apparatus comprises a detector unit, a sensor unit and a filtering sub-unit including a pump and a filter. During a challenge, the pump in the sub-unit is turned off, and the air sample passes from the inlet port of the first unit through the second unit to the output port of the first unit, thereby depositing alarm molecules in the first unit and the second unit. During the clear-down mode, the pump in the sub-unit is turned on, and outside air enters through the output port of the first unit, mixes with air flow from the output of the second unit, and passes through the sub-unit. Filtered air from the sub-unit exhausts the first unit through the inlet port of the first unit and passes into the second unit, thereby cleaning the first unit and the second unit from the alarm molecules deposited therein during the challenge mode.

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Finksburg, MD, United States of America

Peter C Stroosnyder