Task

Sampling using vacuum systems is one of the most frequently used techniques. This system offers considerable advantages, as only one suction hose is required to the sampling point. The suction hose is blown through before and after sampling, which means that the pump does not come into contact with the sample liquid.

A minor disadvantage is that the maximum suction height is limited to around 8-9 metres due to physical conditions. This height is also dependent on the external air pressure. This means that higher suction heights are possible at sea level compared to areas at higher altitudes.

In order to make this efficient system usable for higher suction heights, we have set ourselves the challenge of realising this.

Our solution

Under conventional conditions, a vacuum system causes the sample to rise in the suction hose until pressure equalisation between the generated vacuum and the surrounding air pressure is achieved. At an air pressure of 1,000 mbar and a vacuum performance of the pump of 80 %, the water is sucked up to a height of approximately 8 metres. At an air pressure of only 900 mbar, the suctioned height is only 7.2 metres.

Function

The innovative idea behind our approach was to reduce the weight of the water column in the hose in order to again create a pressure difference between the ambient pressure and the generated vacuum. This draws the water further up the hose.

Thanks to this system, we can draw water from a height difference of over 20 metres and easily achieve a sample volume of around 200 ml. This method may seem like ‘bent physics’ at first glance, but it is actually a very realistic and effective technique.