Process for transferring a liquid using a pump

A process for transferring liquid from a passive tank for storing the liquid to an active tank, using a transfer pump intended for pumping the liquid held in the passive tank and transferring said liquid to the active tank,

• wherein the pump is commanded so as to transfer the liquid from the passive tank to the active tank when said active tank has a liquid level L below a set point level Lsp and when the passive tank contains liquid at a temperature above a freezing point of the liquid,
• wherein said process comprising:
• measuring a temperature Text outside of the active tank and the passive tank;
• checking whether or not the liquid in the passive tank is frozen using the measured temperature Text, former values of Text, and a time constant that corresponds to the liquid in the passive tank changing from a solid state to a liquid state or vice versa;
• comparing the liquid level L in the active tank to the set point level Lsp;
• activating the transfer pump if the liquid in the passive tank is not frozen and L<Lsp, so as to pump the liquid in the passive tank and transfer the liquid into the active tank until a target level Lt is reached, where Lt>=Lsp, and the transfer pump is stopped;
• and
• not activating the transfer pump if the liquid in the passive tank is frozen or if L>=Lsp.