A mixture of recirculated air and outside air which has been conditioned and delivered to the space. Supply air can be 100% outside air and 100% recirculated air.
Air which has been conditioned and delivered to a specific space. Supply air can be 100% outside air, 100% re-circulated air, or a combination.
Air entering the cabinet through the work opening to make up for the volume of air exhausted. In Class II cabinets this air passes through the supply HEPA filter before moving vertically over the work surface.