What equipment is used to mix foam into water in the proper percentages?

The correct answer is the proportioner. This device is essential in firefighting operations that involve the use of foam, as it ensures that foam concentrate is mixed with water at the correct ratios. By doing so, the proportioner creates an effective foam solution that can be deployed on fires, particularly in situations involving flammable liquids.

Proportioners can operate as either fixed systems or portable units, depending on the application and requirements of the firefighting operation. They typically utilize pressure differentials or positive displacement methods to accurately mix the foam concentrate with water, ensuring consistent performance and effectiveness of the foam in extinguishing fires.

In contrast, other equipment mentioned may serve different purposes in firefighting. A master stream refers to a large-volume nozzle used to discharge water or foam over a wide area but does not mix foam with water. A foam generator is used to create foam from the mixture, but is not directly responsible for achieving the correct mixing ratios. A chemical mixer may refer to devices used for general mixing of substances but is not specialized for the specific requirements of mixing foam with water in firefighting scenarios.