What is the function of a clamp for stopping a liquid in a chemical experiment?

What is the function of a clamp for stopping a liquid in a chemical experiment?

The experimental device is connected die al met Countr werken a rubber tube, which is designed to clamp the rubber tube so that the two devices do not communicate.

What is the function of a clamp for stopping a liquid in a chemical experiment?-MasterLi, China Fabriek, leverancier, Fabrikant