(under the class definition) Subject matter comprising a means which senses a change in pressure or air flow resulting
from an explosion or a high intensity air pressure disturbance and said means acting either to allow or to obstruct air flow based upon such sensing.
(1) Note. The devices of this subclass are commonly used in association with bomb shelters, or to allow venting of a ventilated space based upon a severe atmospheric pressure drop (e.g., tornados).
(2) Note. The means usually permits flow in one direction along a conduit while blocking flow in an opposite direction.
SEE OR SEARCH THIS CLASS, SUBCLASS:
3+, for a backdraft preventer incorporated in chimneytop or stacktop structure, particularly subclass 26.
70+, for condition responsive pressure maintenance inside a vehicle which may include a valve.
227, for a backdraft preventer combined with a window. 238, for pressure regulation of a ventilation system which includes both inlet and outlet airways.
255, for pressure regulation of a ventilation system which includes an inlet airway.
259, for a backdraft preventer and an inlet airway.
340, for pressure regulation of a ventilation system which includes an outlet airway.
353, for a backdraft preventer and fan for an outlet airway.
359+, for a backdraft preventer for an outlet airway.
