Recently AVK Industrial Nederland has been able to contribute to a solution for venting pipes in which oil is transported. For this situation we have opted for a plastic air vent with a specially designed float. The challenge here was in the specific mass of the product. The function of an air valve is based on the fact that air is concentrated above the liquid. This opens the air valve so that air leaves the line and the liquid level rises again. The rise in the liquid level in turn ensures that the air vent closes and the medium cannot flow out of the pipe via the air valve. To achieve this, the float of the shut-off mechanism must float on the liquid, in this case oil with a specific mass that is quite different from that of other (neutral) liquids, namely 0.87 compared to 1.0. For this, the weight of the float had to be adjusted in such a way that it floats on the said medium.