Abstract: An air valve that comprises a concave, downwardly facing cover (4) which is carried by a pipe connector (1) connected generally coaxially thereto, wherein the upper edge-part of the pipe connector (1) is surrounded by the wall of the cover (4), a ring-shaped, upwardly facing first seat ridge (8) which is carried by and sealingly connected to the cover wall (5), a second ring-shaped seat ring (2) which is generally coaxial with the cover wall (5) and is carried by and sealingly connected to the upper end-part of the pipe connector (1), and a valve plate (11) which is vertically movable in the cover (4) and which carries an annular, rubber-elastic valve washer (20) that can rest sealingly on the first and the second seat ridges (8, 2) so as to bridge an annular air through-gap between the seat ridges. Both main surfaces of the valve washer (20) have a surface roughness which is adapted to substantially avoid strain in the outer layers of said main surfaces.

Abstract: An air-ventilating valve is adapted to allow the ambient atmosphere to enter a conduit when the ambient pressure exceeds the pressure of gas in the conduit by a essentially predetermined amount, and which also blocks the release of gas from the conduit to the ambient atmosphere. The valve includes two generally coaxial upstanding valve seat projections (6, 7) which lie essentially in a mutually common plane, and a vertically movable valve body (20) which includes a ring-shaped sealing element (4) which bridges an annular gap (5) between the upstanding projections (6, 7) when the valve is closed and sealingly abuts respective sealing projections (6; 7). The valve body (20) is adapted to move to a valve closed position under the influence of gravity. At least one upstanding projection (6, 7) is formed by two radially separated ridges (31, 32) which define an annular trough (33) therebetween. The ridges (31, 32) are both intended to lie essentially tangential to the sealing element (4) when the valve is closed.

Abstract: A reflux valve means for a fluid conduit (30) having a fluid outflow end, wherein the valve means includes a vacuum valve (10) intended for connection to a conduit branch (18) preferably to a top part or rising gradient of the conduit upstream of its outlet end. The valve (10) includes a valve housing (15, 16) provided with a passageway (20, 17, 19) which establishes communication between the atmosphere surrounding the valve and the conduit branch (18). The passageway includes a valve seat (12) and a valve plate (11) which can be moved into and out of sealing contact with the seat (12) under the influence of conduit pressure that is higher than atmospheric pressure. The valve plate (11) of the vacuum valve is constructed to be deformable elastically into and out of a generally dish shape when the valve is closed, under the influence of those pressure variations that normally occur in the fluid in the conduit branch.