In some installed in-line eductor systems, which type of proportioner is used to reduce friction loss?

The bypass proportioner is employed in some installed in-line eductor systems to effectively reduce friction loss. This type of proportioner works by recycling a portion of the water flow back into the system, which helps maintain consistent pressure and flow rates. By diverting some of the water flow, it minimizes the impact of friction loss that can occur within the piping or hoses when water is pushed through the eductor.

Using a bypass system allows the eductor to mix the water with the intended chemical or solution while ensuring that friction loss is kept at a manageable level. This is critical in maintaining the efficiency and effectiveness of the system, especially during firefighting operations where consistent water pressure is essential for proper performance.

Other options, like the around-the-pump or injection proportioners, do not specifically address friction loss in the same way. The around-the-pump method is typically not focused on managing friction but rather on the overall flow around the pump. Injection systems directly add the chemical at a specific point in the system without necessarily accounting for friction loss caused by the system velocity or design. Expansion systems may deal with varying pressures but aren't specifically designed for reducing friction losses.