Bubble Column

Natural History Museum: Earth Galleries Update (Earth's Treasury)

This exhibit demonstrates fluid viscosity and stands 3 metres tall.

Three 2.5 metre long tubes, each filled with silicon fluid, are mounted to a stainless steel housing. The solution in the first tube has a viscosity of 50cS, matching very closely to that of water (1cS). The second and third tubes have viscosities of 1000cS and 2500cS, respectively. Air is pumped into each of the tubes at the bottom and passes through the liquid at different rates, highlighting the differences between each tube. The fluid has been dyed in two of the tubes for purely aesthetic reasons.

The stainless steel case, which houses the pumping unit, was laser cut to shape using CADCAM manufacturing technology. The client wanted bubbles of about 0.75ltrs every 6 seconds in each tube, hence the pumping system was developed to meet this requirement and to enable each pump to last at least three years before requiring any servicing.