What is the expansion ratio for an air aspirating nozzle?

The expansion ratio for an air-aspirating nozzle typically falls within a range of 7:1 to 10:1. This means that for every unit of water introduced into the nozzle, an increase in volume of 7 to 10 units of finished foam or foam solution is created due to the air being mixed with the water.

Understanding the expansion ratio is critical because it directly affects the efficiency and effectiveness of foam application. An accurate expansion ratio also helps in estimating the amount of foam needed for firefighting operations, particularly when dealing with flammable liquids or in scenarios where foam is the primary agent used to smother a fire.

In contrast, the provided options that suggest ratios outside this range (either lower than 7:1 or higher than 10:1) do not align with standard practices for air-aspirating nozzles found in modern firefighting tactics. This specific range is vital for fire officers to understand for effective tactical operations concerning fire control and extinguishment.