In order to fill cooling tanks comprising a compartment for receiving the products to be cooled and a separate coolant-receiving compartment, filling devices are used, with which devices liquid carbon dioxide is injected into the coolant-receiving compartment in a liquefied state and once there is partially transformed into gaseous carbon dioxide and partially into solid carbon dioxide. The filling guns used comprise, in addition to an expansion nozzle, means for drawing off gaseous carbon dioxide, electrical connection means and detectors, in addition to at least one control valve for controlling the supply of the liquid carbon dioxide, and are therefore of a complex design with a high service weight, such that for their operation, they require the assistance of a crane mounting. According to the invention, a filling device is disclosed comprising only one expansion valve for supplying liquid carbon dioxide, one vent opening for drawing off gaseous carbon dioxide, and optionally, non-electrical detector elem
