Aim: Drain a 50 litre tank of oil using a positive displacement pump (see Diagram), so that it drains quicker than gravity alone.
The pump should not be starved at any point.
The flow rate from the 50 litre tank should be at least twice the flow rate from the 5 litre tank.
The 5 litre tank is present because it's used to fill the 50 litre tank (in a different configuration) and also to ensure that the pump is never starved. Once the 50 litre tank is fully drained, the pump should be able to draw oil from the 5 litre tank and then the pump is switched off by a minimum level sensor in the 5 litre tank.
All hoses are 1" inner diameter.
This is where I'm stuck:
In my current setup, will the pump draw the same volume from both tanks at the same rate?
Can I do anything to ensure that the 50 litre tank drains at a much higher rate than the 5 litre tank so I don't have to constantly top up the 5 litre tank?
If I reduce the diameter of the hose from the 5 litre tank or use a valve to restrict the flow, can I achieve a greater flow from the 50 litre tank compared to the 5 litre tank?