Gate valves

Abstract

The invention provides a gate valve comprising a wedge-shaped gate 10 movable into a passageway 11 to seal the passageway, the wedge-shaped gate having first and second sides 13, 14 and a butt region 24, the first and second sides converging towards the butt region, the first side having a perimeter seal 20 facing upstream, the second side having a perimeter seal 21 facing downstream, each perimeter seal merging into a butt end seal 22, 23 for sealing against a face of the passageway, opposed to the butt end, there thus being two butt seals 22, 23 spaced apart with respect to the axis of the passageway, the wedge-shaped gate 10 having a concavity 18, 19 within each perimeter seal to reduce the weight of the gate, the seals being coated with resilient material and the geometry of the valve being such that although the butt end seals 22, 23 undergo a substantially greater degree of compression than the perimeter seals, for a given movement of the gate, the final degree of compression of all the seals, when the valve is finally closed, is substantially similar.

Dependencies are inferred from the claim text.