This part of ISO 10767 establishes a test procedure for measuring the source flow ripple and source impedance of positive-displacement hydraulic pumps. It is applicable to all types of positive-displacement pumps operating under steady-state conditions, irrespective of size, provided that the pumping frequency is in the range from 50 Hz to 400Hz.Source flow ripple causes fluid borne vibration (pressure ripple) and then airborne noise from hydraulic systems. This procedure covers a frequency range and pressure range that have been found to cause many circuits to emit airborne noise which presents a major difficulty in design of hydraulic fluid power systems. Once the source flow ripple and source impedance of hydraulic fluid power pump are known, the pressure ripple generated by the pump in the fluid power system can be calculated by computer simulation using the known ripple propagation characteristics of the system components. As such, this part of ISO 10767 allows the design of low noise fluid power systems to be realized by establishing a uniform procedure for measuring and reporting the source flow ripple and the source impedance characteristics of hydraulic fluid power pumps.