| 20110156715 | Environmental Monitoring System and Method With a Prefilter - Various environmental systems are disclosed. In accordance with one of the systems, a first and second valve are provided. The valves provide a first air flow path from an air pump to a photo-ionization detector is provided through a pre-filter. The valves also provide a second air flow path from the air pump to the photo-ionization detector so that the pre-filter is isolated from its environmental surroundings. Various other arrangements of environmental monitoring systems with one or more pre-filters are also disclosed. | 06-30-2011 |
