Aspirator (pump)

A water pump is a single jet pump is used in the water as a blowing medium.

This technique is often used to create a vacuum or to suck liquids or gases. In the water supply, it is used to aspirate gases such as oxygen or air and to mix the water. The invention is usually attributed to Robert Wilhelm Bunsen.

Design and operation

The water jet pump has two inputs and one output, and basically consists of two nested tubes. It is based on the theory of flow, according to Bernoulli and Venturi. At the water inlet, a water jet occurs under full line pressure from a nozzle into a pipe of larger diameter. Between the fast-flowing water jet and the surrounding medium caused by friction turbulence and subsequently mixing the media. In this process, kinetic energy is transferred from the water jet to the surrounding medium, which is an effective delivery mechanism is available. By conveying out of the medium creates a vacuum in the tube, so can the medium to flow back through the vacuum port. The prerequisite is that the air pressure is at all able to push the water from the high Saugwasserbehälter to jet pump. On Earth, the height difference can be up to ten meters. Therefore, the water pump is not suitable for pumping from deep wells.

So the medium is proportional to the amount of discharged water drawn. Varies the flow - in extreme cases, by rash turning off the tap - also varies according to the achievable vacuum. If the reached in the apparatus pressure is exceeded, water is sucked back into the apparatus, and is then called back. The minimum attainable pressure corresponds to the vapor pressure of water and is therefore dependent on temperature, it is 6 hPa at 0 ° C (see also: Substance values ​​of the saturation vapor pressure as a function of boiling and sublimation ).

The suction power is directly proportional to the water flow.

Areas of application

For use in laboratories coming water jet pumps are usually made of glass, plastic or metal and are connected via a hose or frequently connected by a threaded connection to a water tap. Because of the large water consumption, of high, uncomfortable noise and the pollution of wastewater with possibly high levels of organic solvents, the water jet pumps are increasingly replaced by electrically driven pumps. When using a water pump must always be a safety wash bottle ( bottle Woulfesche ) be attached due to the risk of recoil between apparatus and pump.

Since the pump itself need no drive, no current connection or an internal combustion engine is necessary. Therefore, the pump can also be operated in hazardous areas.

In the fire department, the water jet pump is a water-bearing fitting for water extraction and was especially in the past often used for emptying of fully accrued cellars.