Which action is necessary for handling No. 6 fuel-oil during operation?

For handling No. 6 fuel oil during operation, it is essential to heat the oil for proper flow. No. 6 fuel oil, also known as bunker fuel, is a heavy and viscous oil that requires heating to reduce its viscosity before it can be effectively pumped and atomized in a burner. This heating ensures that the oil will flow smoothly through the system, allowing for proper combustion and efficient operation of the burner.

Heating facilitates the oil's movement through pipes and ensures that it can be mixed adequately with air for combustion. If No. 6 oil is not heated, it may be too thick and could lead to operational issues such as blockage or inefficient burning. Thus, applying heat during handling is a critical step in maintaining efficiency and safety in oil burner operations.