Which design aims to fulfill specified sprinkler density over a selected area fairly uniformly?

The correct answer is hydraulic design because this method specifically focuses on calculating water supply and pressure requirements to achieve the desired sprinkler density throughout a designated area. In hydraulic design, careful calculations ensure that all sprinklers cover the specified area uniformly, taking into account factors such as pipe sizing, friction loss, and pressure levels at various points in the system. This approach ensures that each sprinkler head delivers the intended amount of water to effectively control or suppress fires.

In contrast, pneumatic design involves the use of air pressure and is typically not used for achieving uniform water coverage. Gravity design relies on the natural force of gravity to deliver water, which may not provide adequate control for desired sprinkler densities across an area. Manual design suggests a more subjective approach, lacking the precision and calculations involved in hydraulic design, which could lead to uneven distribution of water and potentially ineffective fire suppression.