Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the underground ventilation duct includes support sidewalls fitting in the shaft providing a ventilation passage between support top and bottom openings and a suspension member supported on opposed lateral sidewalls unobstructively horizontally spanning the passage proximate the top opening and holding one or more hinge connected panels in the passage that manually release to rotationally close the passage and prevent flooding and are manually rotationally liftable to a home position allowing ventilation. The suspension member is liftingly removable from the support and may include end keys received in keyed supports to allow the suspension member to fit in the supports so a specific panel closes to a specific sidewall.

Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the underground ventilation duct includes support sidewalls fitting in the shaft providing a ventilation passage between support top and bottom openings and a suspension member supported on opposed lateral sidewalls unobstructively horizontally spanning the passage proximate the top opening and holding one or more hinge connected panels in the passage that manually release to rotationally close the passage and prevent flooding and are manually rotationally liftable to a home position allowing ventilation. The suspension member is liftingly removable from the support and may include end keys received in keyed supports to allow the suspension member to fit in the supports so a specific panel closes to a specific sidewall.

Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the ventilation duct includes support sidewalls fitting in the shaft providing a ventilation passage between support top and bottom openings and a suspension member supported on opposed lateral sidewalls proximate the top opening holding one or more hinge connected panels that manually release to rotationally close the passage and are manually rotationally liftable to a home position allowing ventilation. A panel drain automatically closes when the panel is raised to home position. A releasable latching system between panel and a suspension member holder catches rising panels to hold them in home position. The suspension member may include end keys received in keyed supports so a specific panel faces a specific sidewall.

Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the ventilation duct includes support sidewalls fitting in the shaft providing a ventilation passage between support top and bottom openings and a suspension member supported on opposed lateral sidewalls proximate the top opening holding one or more hinge connected panels that manually release to rotationally close the passage and are manually rotationally liftable to a home position allowing ventilation. A panel drain automatically closes when the panel is raised to home position. A releasable latching system between panel and a suspension member holder catches rising panels to hold them in home position. The suspension member may include end keys received in keyed supports so a specific panel faces a specific sidewall.

Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the underground ventilation duct includes one or more hinged panels closing a ventilation passage between the top and bottom of a support fitting in the shaft to prevent flooding. The panels have handles on their topside and pivotable arms on their underside and are liftable to an upright home position allowing ventilation, using tools to reach through grating covering openings on the shaft and lift the panel handles and after the panels are partially lifted, using reach tools to engage and lift the arms to press them again support sidewalls to exert lateral force on underside of the panels to complete upward rotation to the home position.

Apparatus allowing ventilation through a ventilation shaft to an underground ventilation duct fluidly communicating through the ventilation shaft to an atmospheric opening of the shaft and on threat of flooding operable to prevent downward flow of surface water into the underground ventilation duct includes one or more hinged panels closing a ventilation passage between the top and bottom of a support fitting in the shaft to prevent flooding. The panels have handles on their topside and pivotable arms on their underside and are liftable to an upright home position allowing ventilation, using tools to reach through grating covering openings on the shaft and lift the panel handles and after the panels are partially lifted, using reach tools to engage and lift the arms to press them again support sidewalls to exert lateral force on underside of the panels to complete upward rotation to the home position.

A dry filter 1 to be used in particular in underground mining and tunnel construction having a frame construction 17 into which the required part housings 25-28 can be inserted from the side. The required partition wall 8 is arranged so that an optimal large filtering surface is available both for the incoming raw gas and for the outflowing clean gas. Raw gas duct 5 and clean gas duct 6 run horizontally one above the other and are separated from each other by the sloping 8. This means that a very large filtering surface is available.

A dry filter 1 to be used in particular in underground mining and tunnel construction having a frame construction 17 into which the required part housings 25-28 can be inserted from the side. The required partition wall 8 is arranged so that an optimal large filtering surface is available both for the incoming raw gas and for the outflowing clean gas. Raw gas duct 5 and clean gas duct 6 run horizontally one above the other and are separated from each other by the sloping 8. This means that a very large filtering surface is available.

Apparatus for allowing ventilation for underground tunnels through a ventilation shaft opening to atmosphere yet preventing underground flooding from surface waters pouring through the grate comprises an assembly that fits within the ventilation shaft and includes one or more panels mounted on a pivot axis and rotatable upwardly by human action raising the panel past a center point of the pivot axis to an upright inwardly leaning home position that allows ventilation as usual but by manual push or pull of the panels past the center point of the pivot axis lets the panels rotationally fall under gravitational impetus to a lower sealing position closing a passage between the ventilation shaft and atmosphere to prevent water from entering the underground tunnels.

Apparatus for allowing ventilation for underground tunnels through a ventilation shaft opening to atmosphere yet preventing underground flooding from surface waters pouring through the grate comprises an assembly that fits within the ventilation shaft and includes one or more panels mounted on a pivot axis and rotatable upwardly by human action raising the panel past a center point of the pivot axis to an upright inwardly leaning home position that allows ventilation as usual but by manual push or pull of the panels past the center point of the pivot axis lets the panels rotationally fall under gravitational impetus to a lower sealing position closing a passage between the ventilation shaft and atmosphere to prevent water from entering the underground tunnels.