Automatic fire-spread preventer valve for ventilation ducts

Claim 2

A thermal safety device adapted, in case of abnormal and sufficient increment in the temperature in a ventilation or airconditioning duct, to automatically close said duct and thus prevent the propagation of fire therealong, which comprises a housing adapted to be inserted between two duct sections, a shutter of resilient flexible flat spring-steel material mounted in said housing and, having a free edge portion, said shutter being adapted to flex between an open position allowing flow through said housing and a closed position preventing flow through said housing, a seat in said housing and adapted to be engaged in face-to-face relation by the free edge portion of said shutter with the latter in closed position, a wire extending through said shutter, and a fusible element on said wire in a position adapted to retain said shutter in its open position by prestressing and bending said shutter whereby, in case of abnormal and sufficient temperature increment in said duct, said fusible element will melt and release said shutter and said edge portion will move into engagement with said seat.

Claim 3

A thermal safety device adapted, in case of abnormal and sufficient increment in the temperature in a ventilation or air-conditioning duct, to automatically close said duct and thus prevent the propagation of fire therealong, which comprises a housing adapted to be inserted between two duct sections, a shutter of resilient flexible flat spring-steel material mounted in said housing and, having a free edge portion, said shutter being adapted to flex between an open position allowing flow through said housing and a closed position preventing flow through said housing, a seat in said housing and adapted to be engaged in face-to-face relation by the free edge portion of said shutter with the latter in closed position, a wire extending through said shutter, and a fusible element on said wire in a position adapted to retain said shutter in its open position by prestressing and bending said shutter whereby, in case of abnormal and sufficient temperature increment in said duct, said fusible element will melt and release said shutter and said edge portion will move into engagement with said seat.

Claim 4

A thermal safety device adapted, in case of abnormal and sufficient increment in the temperature in a ventilation or air-conditioning duct, to automatically close said duct and thus prevent the propagation of fire therealong, which comprises a housing adapted to be inserted between two duct sections, a shutter of resilient flexible flat spring-steel material mounted in said housing and, having a free edge portion, said shutter being adapted to flex between an open position allowing flow through said housing and a closed position preventing flow through said housing, a seat in said housing and adapted to be engaged in face-to-face relation by the free edge portion of said shutter with the latter in closed position, a wire extending through said shutter, and a fusible element on said wire in a position adapted to retain said shutter in its open position by prestressing and bending said shutter whereby, in case of abnormal and sufficient temperature increment in said duct, said fusible element will melt and release said shutter and said edge portion will move into engagement with said seat.

Claim 5

Safety device as set forth in claim 1, comprising a second fusible element and means holding said shutter on said housing by two fastening points wherein said shutter in closed position extends transversely in said housing, said shutter being retained in its open position by said fusible elements symmetrically in relation to a plane containing said two fastening points.

Claim 6

Safety device as set forth in claim 1, wherein said seat is so disposed in said housing that said shutter edges can engage said seat before expanding completely.

Claim 7

Safety device as set forth in claim 2, wherein said fusible elements consist of a pair of balls of a material adapted to melt at said predetermined temperature and each secured to one end of said steel wire.

Claim 8

Safety device as set forth in claim 2, wherein said shutter comprises two elements secured to said housing at opposite ends thereof and adapted, in their closed position, to constitute a relatively streamlined oval obstacle in the housing, said shutters being adapted, in their expanded condition, to form a fluid-tight chamber with the walls of said housing.

Claim 9

Safety device as set forth in claim 1, comprising means by which said shutter is secured along one edge to said housing and in open position lies substantially flatly along said housing.