Suction cup (fixing)

Use

A suction cup is generally used “mechanically to emerge” an inaccessible conduit by other tools. In a domestic environment, the suction cup is used in the Cuisine and the Bathroom, to emerge sinks and flues of waste water. It is a tool easy to use, good market, and often effective. When one does not manage to emerge a conduit using a suction cup, there remains the possibility of chemically attacking the bodies (Organique S) blocking using chemicals.

From which does resistance come from a suction cup?

When one applies a suction cup to a solid substrate, one drives out almost all the Air. When one increases the Volume suction cup while drawing above, its Pression intern decreases.

The force which one exerts while drawing is equal to the product of surface by the difference in pressure between the interior and outside. Very quickly, internal volume strongly increased and the pressure inside becomes negligible . The difference in pressure is then almost constant and equal to the Atmospheric pressure. The force thus remains constant.

In short, if the suction cup resists , it is thus because while drawing, one fights against the atmospheric pressure .

More precisely, the elastic strain of material of the suction cup also contributes to the force. This one is thus not rigorously constant.

When one draws sufficiently extremely, the deformation of the suction cup makes it possible the air to enter. The force falls down then immediately since there is no more difference in pressure between the interior and outside.

Why that made plop?

When the air enters, the abrupt displacement air volume , and the wave of associated pressure, create the sound which we hear, exactly as for the stopper of a wine bottle.

same the plop exists in an adhesive that one takes off , like showed it researchers working on the separation of viscous liquids (external bond).

See too

suction cup

Lampreys

Rémora

Simple: Plunger

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