Wehner blower

Whilst working in the North Thames Gas Board laboratories in 1964, Wehner heard his colleagues protesting at the noise of the electrical pumps used to pressurise the burettes.

Working in glass, he constructed the device illustrated.

Water or other fluid such as mercury enters the instrument at A, and is delivered to the venturi at B. The venturi effect causes gas from C to be dragged into the downpipe D.

This much of the mechanism was conceived by Robert Wilhelm Bunsen, and the device finds application in laboratories as a suction-generator ("Bunsen`s Filter Pump").

Wehner extended the downpipe and added a gas-separator chamber E, so that the gas could be blown out at F.

The liquid itself passes through the connecting pipe G to a header tank H, which may be no more than wide-bore flexible tubing.

The liquid finally leaves the system at J.

The pressure of the gas delivered at F is equivalent to a head of water given by subtracting the height of fluid-inlet G from the height of fluid-outlet J in header-tank H. If gas is not consumed, the level in E will fall to the height of G, and gas will escape with the fluid. If the bore of H is too narrow, a frothy mixture may fill the header tank, reducing the gas-delivery pressure, and leading to an oscillatory condition. Additionally, if fluid outlet J is above gas outlet F, fluid may exit from the gas outlet when all gas has been consumed.

The mechanism may be used as a suction pump, because it contains the Bunsen mechanism. It may be used as a pressure pump, and as a gas-transfer pump.

Several examples were used for a number of years as burette pumps. Colleagues even took some home to aerate their fish-tanks.

The device is particularly suited to the pumping of hazardous gas mixtures, because of the absence of moving parts.

It is also possible to use it as a liquid pump, for example as a mercury-driven water pump.