Ventilating apparatus including exhaust filter exchanger

Ventilating apparatus, comprising:

• a. an exhaust hood having a fume collection chamber, an exhaust chamber, and an interior wall between said chambers having an opening therein to allow fumes to pass from said collection chamber to said exhaust chamber;
• b. a filter exchange assembly having a pair of movable filter holders each for holding at least one filter selectively in operating position across said opening and in reserve position within said exhaust chamber;
• and
• c. means for moving said filter holders for alternatively positioning one of said filter holders in operating position while the other is in reserve position, said means for moving said filter holders having:
• 1. a rotatable central shaft member mounted to said exhaust hood for rotation in said exhaust chamber;
• 2. means for movably mounting said filter holders to said central shaft member for retraction of said filter holders toward said central shaft member and extension away therefrom;
• and
• 3. means for selectively extending said filter holders outwardly from said central shaft member to an extended position wherein one of said filter holders may be in operating position in said interior wall opening and for retracting said filter holders inwardly toward said central shaft member to a retracted position, whereby a filter held by the one of said filter holders in the operating position may be exchanged with a filter held by the other if said filter holders in a reserve position by retraction of said filter holders to their retracted position, rotation of said central shaft member to interchange the positions of said filter holders, and extension of said filter holders to their extended position wherein the other of said filter holders is in the operating position.