For gas filtration and cleaning, gas washing bottles are required which consist of a gas distribution tube, a suitable bottle and a gas outlet opening. In this test setup, the gas is forced to flow through a liquid before it is released. The gas distribution pipe is immersed in the liquid for this purpose, the gas interferes through it and impurities of the gas are bound in the liquid. The gas is cleaned or washed so to speak. A filter disk in the gas distribution tube creates air bubbles that are as small as possible and thus form as large a contact area as possible.