Optimal tapping of metallurgical furnaces is required for efficient furnace operation. Improper tapping can lead to metal and slag accumulation in the furnace thereby reducing the process efficiency. The mass flow rate of metal and slag during tapping in metallurgical furnaces is driven by the hydrostatic pressure head, i.e., the liquid level, and hindered by the porous particle bed formed by the raw materials in the furnace. To understand the effect of the particle bed, experiments were performed on a lab-scale tank fitted with a tap-hole using water and a mineral oil as fluids emulating the real furnace. The tank was filled with only water and both water and oil and their drainage rates were measured as they were emptied by gravity. The tank was then filled with glass beads to include the effect of the particle bed, adding an extra pressure drop due to the resistance offered by the glass beads and reducing the mass flow rate of the fluids. A significant effect of the particle bed was observed on the tapping flow rates. The presence of air bubbles in the oil and the water phase reduced the tapping flow rates of the phases even in the absence of the particle bed.