Self-closing vent

A method of permitting the flow of ventilation air through a vent during normal ambient conditions and restricting or preventing the flow and a spread of embers through the vent during a fire, said vent comprising a first vent member having a plurality of first apertures and a second vent member having a plurality of second apertures, the method comprising:

• moving by air the first vent member from a first position spaced apart from the second vent member along a direction toward the second vent member to a second position abutting the second vent member when said air has a velocity not less than an activation velocity, wherein the plurality of first apertures are misaligned from the plurality of second apertures axially along an axis along said direction, wherein said plurality of first apertures and said plurality of second apertures are defined along planes generally perpendicular to said direction, and wherein when said first vent member is in said second position, the flow of embers is restricted or prevented through said vent;
• and
• allowing the first vent member move to the first position by its own weight when the air velocity is below said activation velocity.