The pressure-wave speed is a fundamental parameter for hydraulic transient modeling, since it determines how quickly disturbances propagate throughout the system. This affects whether or not different pulses may superpose or cancel each other as they meet at different times and locations. Wave speed is affected by pipe material and bedding, as well as by the presence of fine air bubbles in the fluid. The default value of 1,000 m/s (3,280 ft./sec.) is for metal or concrete pipe.

Although higher wave speeds are conservative for typical systems composed of a single pipe material, such as pipelines, consider a few extra model runs to assess the sensitivity of the hydraulic transient simulation results to global changes in wave speed; you can change it on the Summary tab of the Options window (Tools > Options).