What operating principle do simple in-line foam eductors use?

Simple in-line foam eductors operate based on the Venturi principle. This principle involves the creation of a low-pressure area within the eductor as water flows through a constricted passage. As the water accelerates through the narrowed section, its velocity increases while its pressure decreases. This pressure reduction draws foam concentrate into the water stream from an external container, mixing it along the way.

The Venturi effect is fundamental to the functionality of foam eductors, enabling efficient foam generation. By optimizing water flow and pressure, these devices provide a reliable method for delivering foam to combat fires, particularly in situations where foam suppression is required. Understanding this principle is crucial for effective firefighting operations, as it ensures that the appropriate amount of foam concentrate is introduced into the water stream, enhancing fire suppression efforts.