Which of the following is NOT one of the three groups of nozzles?

In the context of firefighting nozzles, the three primary categories are solid-stream nozzles, fog-stream nozzles, and combination nozzles. Each category serves distinct purposes based on the water flow and dispersion method, which are critical in fire suppression strategies.

Solid-stream nozzles are designed to produce a concentrated stream of water that can penetrate deep into the fire. This is effective for reaching the heart of a blaze, particularly in structural fires or during defensive operations.

Fog-stream nozzles create a mist of water droplets, allowing for better dispersal and cooling effect, which can be beneficial in protecting exposures and in situations where heat absorption is necessary without the risk of steam burns due to rapid evaporation.

Combination nozzles offer versatility, allowing firefighters to switch between solid and fog streams as needed, providing tactical flexibility on the fireground.

Low-pressure master stream nozzles, while a valid type of nozzle, are not considered one of the three primary groups of nozzles as outlined in most training curricula. Instead, they are often classified separately due to their specific application — typically used for delivering large volumes of water from a distance.