A one-way valve configured to allow a hollow filling element, such as a tube or a hose, to pass through the one-way valve from a first side of said one-way valve to an opposite, second side of said one-way valve, and blocking an insulation material, such as polyurethane, from said second side to said first side of said one-way valve, said one-way valve comprising: - a first body provided with a first opening and first movable elements that are spaced apart along a circumference of said first opening; - a second body provided with a second opening and second movable elements that are spaced apart along a circumference of said second opening; wherein said first movable elements and said second movable elements are movable between first positions, defining an open state of said one-way valve for allowing said hollow filling element to pass through said one-way valve and second positions, defining a closed state of said one-way valve for blocking said insulation material wherein, in the second positions, said first movable elements and said second movable elements contact each other thereby closing said first opening and said second opening; wherein said second opening is provided at a side of said first opening facing said second side, wherein said second opening is aligned with said first opening for allowing said hollow filling element to pass through said first opening and said second opening; and wherein each of said first and second movable elements (13, 17) extend in a direction away from said first side and such that each of said first movable elements extends through the second opening and at least partly between neighbouring second movable elements. - a first body provided with a first opening and first movable elements that are spaced apart along a circumference of said first opening; - a second body provided with a second opening and second movable elements that are spaced apart along a circumference of said second opening; wherein said first movable elements and said second movable elements are movable between first positions, defining an open state of said one-way valve for allowing said hollow filling element to pass through said one-way valve and second positions, defining a closed state of said one-way valve for blocking said insulation material wherein, in the second positions, said first movable elements and said second movable elements contact each other thereby closing said first opening and said second opening; wherein said second opening is provided at a side of said first opening facing said second side, wherein said second opening is aligned with said first opening for allowing said hollow filling element to pass through said first opening and said second opening; and wherein each of said first and second movable elements (13, 17) extend in a direction away from said first side and such that each of said first movable elements extends through the second opening and at least partly between neighbouring second movable elements. wherein said first movable elements and said second movable elements are movable between first positions, defining an open state of said one-way valve for allowing said hollow filling element to pass through said one-way valve and second positions, defining a closed state of said one-way valve for blocking said insulation material wherein, in the second positions, said first movable elements and said second movable elements contact each other thereby closing said first opening and said second opening; wherein said second opening is provided at a side of said first opening facing said second side, wherein said second opening is aligned with said first opening for allowing said hollow filling element to pass through said first opening and said second opening; and wherein each of said first and second movable elements (13, 17) extend in a direction away from said first side and such that each of said first movable elements extends through the second opening and at least partly between neighbouring second movable elements.