FILTER SHIELD

摘要

A gas sampling system for a coal mill has a filter shield assembly (30) for a flexible filter (24) attachable to the probe of the gas sampling system. The filter shield assembly (30) is offset from the filter (24) to provide sufficient gas flow along the sides of the filter (24) to set up gas currents for flexing or fluttering the filter to dislodge any particulate matter trapped in the filter. The filter shield assembly (30) comprises inner and outer spaced concentric shields with the outer shields overlapping the spaces between the inner shields thereby to prevent particulate matter from entering the analyzing system and preventing direct impingement of particulate matter on the filter (24).