Cavitation is the phenomenon of vaporisation of fluids under the effect of depressurisation, i.e., low pressure caused by high flow velocity. It occurs in many hydraulic machines and components whose effective range of operation is limited by the appearance or development of the phenomenon. Vaporisation of a liquid is the change of phase that converts it into the vapour state. This transformation is mostly brought about by adding heat, as in the case of boiling in heating systems or more commonly in a casserole. It can also be achieved by depressurisation, for example in evaporators in desalination factories. In some cases, vaporisation is accomplished by a combination of heat addition and reduction in pressure. All liquids are susceptible to cavitation as soon as the pressure attains a value equal to the vapour pressure.