Abstract: A fluid delivery and mixing method and apparatus for mixing at least two fluids wherein the fluids are stored under pressure in separate accumulators and are supplied substantially simultaneously to a mixing chamber, the pressure decay characteristics of each of the accumulators being controlled to have substantially the same shape. The characteristics of the fluid components, the size of the input ports to the mixing chamber and the pre-determined pressures to which the fluids in the accumulators are charged being selected so that the ratio of the flow rates by weight of the fluids at the input ports is a constant and so that the momenta of the fluids at the input ports are equal.