| 摘要 |
A filter alert device ( 10 ) for use in forced air systems ( 50 ) used to distribute conditioned air comprises an indicator that operates with an air filter ( 30 ) supported by a register ( 50 ). The filter ( 30 ) and filter alert indicator ( 16 ) have cavities in communication with at least a portion of the air passing through the filter ( 30 ). The air pressure varies in response to the flow through the filter ( 30 ) and exceeds a predetermined pressure when the air is unable to flow through the filter ( 30 ) at desired pressure levels and the life of the filter has been exceeded. In one embodiment, the indicator ( 16 ) is attached to a frame for movement between closed and open positions wherein the indicator ( 16 ) remains in closed position to show that the filter ( 30 ) is operating within desired operating parameters, and the indicator ( 16 ) is positioned to the open position that projects out of the register to alert users that the filter is no longer operating within the desired operating parameters and should be replaced or cleaned. A pressure sensitive attachment element holds the indicator in the closed position when the pressure is below the predetermined pressure and the filter is operating within desired parameters, and releases the indicator when the pressure exceeds the predetermined pressure and the filter is no longer operating within desired operating parameters.
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