The plunging siphon is a very simple instrument for sampling of homogeneous fluids from vessels, tanks, containers (for instance tank lorries) and basins. As glass plunging siphons tend to break easily the unbreakable translucent teflon is applied. The inert teflon is not affected by chemicals avoiding the sample to be contaminated by the equipment. The plunging siphon is heat resistant to a temperature of 250°C. After removal of the narrowing cones a plunging siphon can be cleaned easily. The plunging siphons are supplied in a long (180 cm) and a short (90 cm) design inclusive narrowing cones for liquids with different viscosity, and with a protective tube.