I'm excited about the options you've found. Of course with the flow transmitter and level sensor, the devil's in the details (specifically accuracy). Controlling the exact volumes of liquid might be tricky with standard pumps...
Accuracy will have to be sacrificed some, but that can be fixed later with higher-end instruments once I verify the system works well enough. I'm more worried about repeatability. I can tolerate some inaccuracy as long its consistent.
I was wondering if a tube pump could be used to provide exact volume controls.
I'm not familiar with those, but I'll do some checking around. I assume its a positive displacement pump? I recently decided to take a different route than what I listed above. Instead of using my Chugger pumps and adding a modulating control valve to regulate flow, I was going to replace my pumps with something like these
Variable Speed Solar Pumps. I can vary the speed to control flow rates by sending it a 0-5V signal.
As for clean in place, a 6" triclamp port on the bottom of your mash tun makes it a bit easier - of course that part will be manual and not automated but oh well.
Actually, I think I could still automate that, but that would take some engineering to get a large port that opens on the side of the kettle (and will still seal tightly). There's a process called Air Scour (or Filter Backwash) that wastewater plants use where if you flowed water at high rate from the bottom (so IN the outlet) and pumped a large volume of air in from under the false bottom, it should create enough turbulence to carry most of the grain out of the large drain port with the water. If I'm already going to need a high flow pump for the CIP balls, I could utilize that and my air compressor. I doubt I'd ever go through this effort when a shop vac works, but who knows, I might get bored and want to add another step to the process one day.
Couple other things I ran into:
-full drain / pump - since brewery pumps can't push air, must consider the liquid left in the pipes after each stage of the process. I really wish I could find a solution to this - there can be 1L+ left in piping!
I think the air compressor tied into the tubing system with a solenoid valve should take care of this. The valves in the system could isolate different sections so you could blow it out effectively. I work for a control valve company, so I could get a knockout filter easily to try to clean up the air some. I'd buy the valves from work too, but everything we sell is higher spec and $$$$.
-clean in place: you need a certain PSI pressure in the pipes and spray balls for them to operate. Common home brew pumps won't cut it, need a lot more pressure. Shouldn't be too pricey, there are <$100 pumps that can do 60PSI.
Ok, thanks. I didn't know that. I think I saw some when I was searching around, but I like the idea of having a dedicated pump for the CIP system as well. Does it need a high volume as well?
-cip: ball valves are not sanitary, period. Even butterfly valves technically aren't sanitary. So far the only option I've found is "isolation diaphragm valve" - found them on alibaba with actuator for ~$100-$150 each but never got a response from the vendors.
I did a quick search on the diaphragm valves and couldn't find any that I liked, but I did get a good laugh out of these
High TEMPRESSURE Valves 
I'll do some more checking into it.
-cip2: those valves, and pipes for that matter, need to be at a 15 degree offset off the horizontal to enable full drain, else you get standing water and thus unsanitary conditions.
The compressed air blow-out should take care of this, but I may still put some angles to it so gravity can help.
And, of course the final challenge is programming: even brewtroller, as of now, needs work to support all the logic you desire.
I've got this part covered (sort of). My system is already controlled by a PLC and 15" HMI. Both pieces of hardware have plenty of programming capability. I only say 'sort of' because I'm not highly trained on programming. I just know enough to fumble my way through it and eventually get it working with the help of forums and IOM's.
Oh and liquid level sensing: found this a few links away from your sensor:
http://www.milonetech.com/uploads/Chemical_eTape_Datasheet.pdf
much greater resolution than the infrared distance sensor. Food safe too.
I would much rather use one of those eTape's, but they are only rated to 150F. I'm still looking for one that is rated for higher temps.
I appreciate all the ideas and suggestions!
