What are the components on an impeller that are designed to assist in directing water to the edge?

The correct answer is vanes. In the context of an impeller used in fire apparatus, vanes are specifically designed components that play a crucial role in guiding and directing the flow of water as it moves through the impeller. They help to create a pressure differential that enables the water to be propelled outward, maximizing the efficiency of the impeller's function while ensuring a smooth transition of water from the center to the edge.

Vanes are shaped and positioned to enhance the hydraulic performance by manipulating the water's flow direction. This design allows for better control over the output flow rate and pressure, which are essential factors in firefighting operations. Properly designed vanes help mitigate turbulence and promote laminar flow, enhancing the overall effectiveness of the water delivery system. Understanding the role of vanes in this process is vital for anyone operating fire apparatus equipped with pumps.