Edward J Gray

US Patent:

58109080, Sep 22, 1998

Filed:

May 2, 1997

Appl. No.:

8/850064

Inventors:

Edward G. Gray - Rowlett TX
John W. Seaman - Sheboygan Falls WI

Assignee:

Bemis Manufacturing Company - Sheboygan Falls WI

International Classification:

B01D 4646

US Classification:

95 25

Abstract:

An air filtering apparatus including motor selectively connected to a power source, a fan driven by the motor and creating an air flow, a replaceable filter element selectively positioned in the air flow path, and an electronic control. The electronic control includes a clogged filter element detector and an indicator and a missing filter element detector. The current drawn by the fan motor is sensed by a current transformer and compared to a predetermined threshold by a comparator in each detector. If the current drawn by the fan motor is less than the clogged filter element predetermined threshold, the clogged filter element detector operates an indicator. If the current drawn by the fan motor is greater than the missing filter element predetermined threshold, the missing filter element detector operates a controller to disconnect the fan motor from the power source.