Utilising selective withdrawal in the ventilation of large rooms: "Select-vent".

This paper presents a way of ventilating a large room so that the room can be divided into different zones by temporary vertical walls (canvas, plastic sheets etc) and with no physical ceiling. Different activities, like welding, painting or mechanical assembly, can go on inside each of these zones, unaffected by each other, as long as pollutants are extracted through designated extract openings in the outer walls. These inner, temporary walls need only reach from say 3 - 4 metres above the floor and up to some metres above the pollutants' height of equilibrium. Thus, transport at floor level can go on between the different zones, and traverse cranes can pass freely above the zones. This principle has been developed by for practical industrial ventilation, and we designate it "Select-vent".