A flow regulating device 2 comprising a plurality of coaxial vortex chambers 16, 116, 216, 316 disposed in flow series. Each vortex chamber 16, 116, 216, 316 has an inlet 22, 122, 222, 322 disposed to promote rotational flow within the vortex chamber 16, 116, 216, 316, and an outlet 24, 124, 224, 324. A diffusion chamber 12, 112, 212 is disposed between adjacent vortex chambers 16, 116, 216, 316, and the outlet 24, 124, 224, 324 of one and the inlet 22, 122, 222, 322 of the other of the adjacent vortex chambers 16, 116, 216, 316 open into the diffusion chamber 12, 112, 212.