Liquid seal valve

A liquid seal valve comprising a first vessel having a lower part which includes a closed bottom and a wall extending upwardly from said bottom and a gas outlet from an upper part of the vessel, a second, open-topped vessel within the lower part of said first vessel, said second vessel having a wall extending to said closed bottom end spaced upwardly from said wall of the first vessel providing a radial gap between said walls of said first and second to vessels, a gas inlet pipe extending downwardly through said upper part of the first vessel and through the open top of said second vessel into a liquid trap in said second vessel, the lower end of said gas inlet pipe being disposed below the level of the surface said liquid trap when there is no gas flow through said inlet pipe, whereby gas entering the valve via said inlet pipe can flow via said second vessel to the gas outlet in said first vessel, and pipe means providing communication between the lower end of said gas inlet pipe and at least two regions in said first vessel, said pipe means including a first, open-ended pipe externally of, and to one side of, said second vessel, said first pipe being disposed in said radial gap and having a smaller cross-sectional area than said second vessel, said first pipe having a first open end below said level and a second open end above said level, and a second pipe connected to said first pipe intermediate the first and second open ends of the latter, said second pipe leading from said first pipe to the interior of said second vessel and having an open end opposite to, and adjacent to, the lower end of said gas inlet pipe.