Abstract: An air extraction hood, which comprises a canopy defining an enclosed air collection and treatment zone, and having an operatively downwardly directed air inlet through which air to be treated can enter the zone, as well as an air outlet through which air can be discharged from the zone, the canopy being mountable with clearance above a cooking surface such that its inlet is located above the cooking surface; mounting means for mounting treatment means inside the canopy in the collection and treatment zone, between the inlet and outlet; and passageway defining means defining an air passageway between the inlet and the mounting means along which air can pass, with at least part of the passageway defining means being curved over at least a major portion of the distance from the inlet to the mounting means, to enhance air flow along the passageway.

Abstract: A separation process comprises passing a gas or vapor stream contaminated with an undesired substance or contaminant downwardly through a plurality of spiral separating media such that the direction of movement of the gas or vapor stream is transversely the longitudinal axes of at least some of the spiral separating media. The undesired substance or contaminant is allowed to separate from the gas or vapor as it passes through the bed, and purified gas or vapor is withdrawn from the bed.

Abstract: A separation process comprises passing a gas or vapor stream contaminated with an undesired substance or contaminant downwardly through a bed of curled separating media. The undesired substance or contaminant is allowed to separate from the gas or vapor as it passes through the bed. Purified gas or vapor is withdrawn from the bed.