pryce227:
- A pump which can be programmed to pump fairly small volumes of water (1 mL to 100 mL) through a tubing into a container at pre-set, easily modified intervals (between every minute to every 24 hours)
Peristaltic pumps can do this just fine.
- A drain which is inserted into the same container, and which can have optionally have suction applied to it (from 0 to -40 cm H20). This drain goes to a waste container.
This part I don't really understand.
You want something like a pump inside the drain, where the container is attached to the pump inlet and the waste to the pump outlet? Basic impeller pumps will let water pass through (at rates way greater than your input), and when switched on will suck the water in. Unless you put some valve in it, this will easily get you flows of hundreds of litres an hour.
- A way to monitor the output of the drain which modulates the input of the pump. I don't want to blow out the container walls, so I need to make sure output > input. There needs to be a running count of how much volume is pumped into the container and how much volume is drained out of the container, and if more volume is being pumped in than out, then pump function must be suspended until output "catches up".
This is a trickier part. There are lots of different flow meters, but it seems you're looking at rates in the order of a few millilitres per hour, making measuring the flow a bit trickier.
- A real-time display of the volume pumped in and the volume drained out.
This can be anything from a basic 1602 LCD (16 characters, two lines) to a nice colour screen.
I'm not anywhere close to your location, however I am located close to the source of all those components (I live in Hong Kong). It seems the only components that I don't have on hand of the list above are the nice colour screen and the flow meter.