How does a smooth bore nozzle affect the diameter of the stream?

A smooth bore nozzle is designed to produce a solid, narrow stream of water that maintains its shape more effectively than other nozzle types under pressure. When water flows through a smooth bore nozzle, the diameter of the stream typically decreases compared to the inlet size of the nozzle. This decrease in diameter occurs because the nozzle constricts the flow of water, which increases the velocity of the water as it exits, creating greater pressure.

The design of the smooth bore nozzle allows for the creation of a highly effective stream that can reach greater distances due to the increased kinetic energy of the water, which is critical in firefighting scenarios where precision and reach are necessary. This principle of reducing diameter to increase pressure, and thus stream reach, is a fundamental characteristic of how smooth bore nozzles operate.

In contrast to the other options, a smooth bore nozzle does not enlarge the diameter of the stream for coverage, have no impact on diameter, or create a fan-shaped stream; these characteristics are more aligned with other nozzle types or flow configurations. Understanding the operation of a smooth bore nozzle helps firefighters select the right tool for various fire scenarios, where reach and focus of the water stream play a pivotal role in extinguishing fires effectively.