Hi please answer briefly on the highlighted instruction since im a slow learner.

The use of a continuous atmospheric gravity separator which is also known as decanter is widely applied in separating immiscible liquids that are having distinct densities. Figure 1 shows a decenter that separates two immiscible liquids (Liquid A and B) in which liquid B having higher density than liquid A. The feed mixture enters the unit at one end of the separating vessel and flows slowly to the other end which eventually cause the mixture to separate itself into two distinct layers. Liquid A and B flow out at the overflow lines to the respective collection tank which are open to atmosphere. For a properly designed decanter and assuming that the frictional resistance to the flow of the liquid is essentially negligible, analyze the effect of the density of both liquids to the vertical height of the liquid B (ha & he2). Subsequently show that the vertical height of the liquid interface (hai) depends on the vertical difference of both overflow lines. Elaborate the purpose of having the overflow line of liquid B to be elevated at certain height, h92. Vent (open to atmosphere) Feed in 1 overflow lines ha Liquid A he 1 hei hez Liquid B Collection tank for liquid B Collection tank for liquid A Figure 1 Decanter unit for two immiscible liquids A & B