Jet air fireplace

An air door or air curtain is a device used to prevent air or contaminants from moving from one open space to another. The most common use is a downward-facing blower fan mounted over an entrance to a building , or an opening between two spaces conditioned at different temperatures.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) defines an air door as follows: "In its simplest application, an air curtain is a continuous broad stream of air circulated across a doorway of a conditioned space. It reduces penetration of insects and unconditioned air into a conditioned space by forcing an air stream over the entire entrance. The air stream layer moves with a velocity and angle such that any air that tries to penetrate the curtain is entrained. Air curtain effectiveness in preventing infiltration through an entrance generally ranges from 60 to 80%". [1]

The Air Movement and Control Association defines an air curtain as: "A directionally-controlled airstream, moving across the entire height and width of an opening, which reduces the infiltration or transfer of air from one side of the opening to the other and/or inhibits flying insects, dust or debris from passing through".

Editor’s Note: For a more complete. updated analysis of the World Trade Center towers collapse, read “ The Role of Metallurgy in the NIST Investigation of the World Trade Center Towers Collapse ” in the December 2007 issue.

Why Did the World Trade Center Collapse? Science, Engineering, and Speculation by Thomas Eagar and Christopher Musso

An Initial Microstructural Analysis of A36 Steel from WTC Building 7 by J.R. Barnett, R.R. Biederman, and R.D. Sisson, Jr.

shutter means operably movable over said window means for opening and closing said window means from a point remove from said window means,

said shutter means comprising a guide plate extending from a channel shaped member and being provided with a guide aperture for slidably guiding or said gas jet means, and

adjustment rod means coupled to said shutter means and extending to an accessible point on said fireplace for opening and closing said shutter means remote from said air/gas valve.