The Darcy-Weisbach equation is a fundamental formula used in fluid mechanics to calculate the pressure loss due to friction in a pipe. It relates the pressure drop to the length of the pipe, the flow velocity, the fluid's density, and a dimensionless factor known as the Darcy friction factor. This equation is essential for engineers designing piping systems to ensure efficient fluid transport. The equation is expressed as ΔP = f * (L/D) * (ρ * v²/2), where ΔP is the pressure loss, f is the Darcy friction factor, L is the pipe length, D is the pipe diameter, ρ is the fluid density, and v is the flow velocity. Understanding this equation helps in optimizing system performance and reducing energy costs.