Pressure relief means for industrial vacuum

Claim 1

In an industrial vacuum unit having means for creating a flow of air and creating both a negative vacuum pressure and a positive pressure, pressure relief means comprising: a housing mounted to said vacuum unit and having dividing means for partitioning said housing into a lower inlet chamber and an upper outlet chamber; said vacuum unit having an opening and said inlet chamber having a first opening for receiving air from the vacuum unit through said opening and admitting same into said inlet chamber; said dividing means having an opening for air flow between said inlet and outlet chambers; said outlet chamber having outlet means providing an opening for releasing air from said housing; movable sealing means mounted adjacent said outlet means; and, support means mounted to said housing intermediate said outlet means and said movable sealing means and engageable with said movable sealing means to cover said outlet means for providing an air-tight seal of said outlet means for preventing the flow of air through said pressure relief means when said negative vacuum pressure exists in said industrial vacuum unit and for permitting movement of the sealing means away from the support means to allow the flow of air through the outlet means and the support means when positive pressure exists in said vacuum unit; filter means mounted in said outlet chamber for removing particles from said flow of air passing through the housing; and said inlet chamber having guide surface means extending below said filter means downwardly towards and in communication with said first opening for receiving said particles falling from the filter means and for downwardly directing these particles through said first opening and the opening of said vacuum unit and thereby into said industrial vacuum unit.