Abstract: A pump (18) draws liquefied carbon-dioxide from a reservoir (4 or 6) and delivers it via a controllable heater (20) and a filling valve (14) to a cylinder (26) to be filled to any required density. This receiver cylinder (26) is controllably warmed by a heater (32) while sensors (22,24) are provided to indicate the pressure and temperature of its contents. For each required density a table of figures is provided relating pressures (above saturation pressure) to temperature, for that density. A temperature (which must be clear above the lowest temperature at which the receiver will be liquid-full at the required density but which need not exceed the critical temperature) is selected, and the heaters (20 and 32) are controlled so that the receiver cylinder and its contents will converge at or near that temperature as filling is completed. During the final phase of filling the indicated temperature will rise slowly and the pressure (from the time the receiver is liquid-full) will rise relatively fast.

Abstract: A pump (18) draws liquefied carbon-dioxide from a reservoir (4 or 6) and delivers it via a controllable heater (20) and a filling valve (14) to a cylinder (26) to be filled to any required density. This receiver cylinder (26) is controllably warmed by a heater (32) while sensors (22,24) are provided to indicate the pressure and temperature of its contents.For each required density a table of figures is provided relating pressures (above saturation pressure) to temperature, for that density.A temperature (which must be clear above the lowest temperature at which the receiver will be liquid-fill at the required density but which need not exceed the critical temperature) is selected, and the heaters (20 and 32) are controlled so that the receiver cylinder and its contents will converge at or near that temperature as filling is completed.During the final phase of filling the indicated temperature will rise slowly and the pressure (from the time the receiver is liquid-full) will rise relatively fast.