What are the two primary types of foam proportioners used in firefighting?

The two primary types of foam proportioners used in firefighting are indeed the foam eductor and foam injector.

A foam eductor uses the venturi effect to draw foam concentrate into the water stream. As water flows through the eductor, it creates a vacuum that pulls the foam concentrate from a container, mixing it with the water in the appropriate ratio for effective firefighting. This method is widely used due to its simplicity and efficiency, particularly for portable firefighting systems.

On the other hand, a foam injector operates by using a positive displacement pump that forces the foam concentrate into the water stream at a predetermined ratio. This technology allows for more precise control of the foam mixture and is often utilized in larger fire apparatus and fixed systems where consistent foam application is necessary.

The other options do not reflect established terminology or types used in the firefighting industry. They do not accurately describe recognized methods of mixing foam with water for firefighting endeavors. Understanding these two main types helps firefighters utilize foam effectively in various emergency situations, allowing for more efficient fire suppression and better handling of hazardous materials.