Abstract: A fluid oscillator for producing pulsations in a flow of fluid, having a housing with a fluid inlet channel for connection to a supply of fluid under pressure, a fluid outlet channel, and a diaphragm valve which alternatively opens and closes causing intermittent flow of fluid from the fluid inlet channel to the fluid outlet channel. The valve opens due to the fluid supply pressure in the fluid inlet channel and the valve closes due to a reduction in pressure caused by the inertia of the fluid in the fluid outlet channel. A pressure accumulator is located adjacent to the inlet channel to absorb fluctuations in fluid pressure in the inlet channel. An elastic separator element is located in the housing to define a gaseous compartment in the pressure accumulator, so that pressure fluctuations in the fluid inlet channel are generally absorbed or attenuated by compression and expansion of the gas in the accumulator.