Abstract: A safety system, particularly for use with fire fighting tankers, comprising a device whereby at least part of the contents of the tank can be caused to be rapidly discharged and having a hatch for the ingress into the tank of at least one person, the hatch being capable of being sealed after the person is in the tank so that the person is isolated from the surrounding atmosphere. Preferably the tank has a layer of insulating material thereabout, which layer maintains the temperature within the tank below a dangerous level for a person therein, at least for a period equal to the likely incidence of high temperature thereon.