Kinda like turning on the garden hose and waiting for it to FILL and get to the nozzle. Turn it off (kill the pumping action) before it gets there and no water at the nozzle. Simple hydaulics but I've forgotten the formulas. It's been 20 years.
You nailed it. I was trying to find a way to express what I meant and all I could think of was circulate. So that means it would just "sit" at a certain area and the doctor could probably determine from that right?