Which foam proportioning method involves injecting foam concentrate into a water or foam master stream?

• A. Induction/eduction
• B. Injection
• C. Batch mixing
• D. Premixing

Answer: (B)

Foam proportioning using injection means pushing foam concentrate under pressure into the water line or a foam master stream through a dedicated injector or proportioning device. This creates the foam solution immediately as it enters the flow, giving precise control over the concentrate ratio and rapid, on-scene foam production. This is especially useful when you need to adjust foam concentration quickly or cover large areas with a consistent foam blanket.

Induction/eduction works differently by pulling concentrate into the water stream through a venturi or eductor without a positive injection pump, relying on flow-created suction. Batch mixing combines concentrate with water in a separate tank before discharge, and premixing mixes the concentrate with water ahead of time in a storage or supply line, not adjusted during operation.