What process involves mechanically ventilating a compartment with fresh air to remove vapors and inert gas?

Gas-freeing is the process that involves mechanically ventilating a compartment with fresh air in order to remove vapors and inert gas. This procedure is essential in ensuring that the atmosphere within the compartment is safe for personnel to enter and work. When tanks or other enclosed spaces have been used to carry flammable or toxic substances, they may contain harmful vapors that pose a risk during inspection, maintenance, or repair work.

During gas-freeing, fresh air is introduced to dilute and eventually expel these hazardous vapors, thereby reducing their concentration to a safe level. This is typically achieved using fans or blowers that circulate air effectively throughout the space. It is a critical safety measure in tanker operations and various industrial settings, ensuring compliance with safety regulations before anyone enters the tank.

Other options such as cleansing, ballasting, and inerting refer to different processes. Cleansing generally pertains to the removal of residues or contaminants, ballasting involves taking on water to increase stability, and inerting means replacing the oxygen in a space with an inert gas to prevent combustion. None of these involve the specific action of ventilating with fresh air to create a safe environment for entry, which distinguishes gas-freeing as the correct answer.