liquid sensor - I've been thinking.........

If I recirculate through a grain bed, in at the top, out at the bottom, through the pump and back in at the top a simple closed loop.

If the flow through the bed was too slow then the pump would suck all the wort from under the grain be and could be damaged, I would like something that would switch the pump off if this happened rather than have to stand there adjusting flow rates.

What would I need to do or what sensor could I use to prevent the pump running dry?


Many Thanks. Aamcle

You could DIY something perhaps by taping foil sheets either side of a silicone tube leading to the pump as a capacitative liquid sensor. Crappy instructable demonstrates -->

http://www.instructables.com/id/Building-a-Capacitive-Liquid-Sensor/

Arduino and a flow sensor??? You could have the Arduino switch the pump on and off depending on the flow.

http://www.ebay.com/itm/1-30L-min-2...239?pt=LH_DefaultDomain_0&hash=item2580e6824f

I've spent some time thinking about this and I can do it with a "jam jar" and a float switch, not high tech but easy to do and should be reliable.

I'm starting to get the bits for the build together


Thanks for your help. Aamcle

I've got one of these

http://www.ebay.com/itm/NEW-Ultra-S...072?pt=LH_DefaultDomain_0&hash=item3f13320208

I should try it for use on liquid levels - we've used something similar at work for liquid levels.

atoughram said:

I've got one of these

http://www.ebay.com/itm/NEW-Ultra-S...072?pt=LH_DefaultDomain_0&hash=item3f13320208

I should try it for use on liquid levels - we've used something similar at work for liquid levels.

Click to expand...

The issue is whether it will work for boiling/foaming liquids.

atoughram said:

Arduino and a flow sensor??? You could have the Arduino switch the pump on and off depending on the flow.

http://www.ebay.com/itm/1-30L-min-2-0MPa-1-2-Hall-Effect-Flowmeter-Control-Water-Flow-Sensor-Arduino-/161076380239?pt=LH_DefaultDomain_0&hash=item2580e6824f

Click to expand...

I haven't had much luck with flow sensors and Arduinos, it may depend on what else you're doing on the Arduino but the interrupts are limited and I had concerns on the impact to the rest of my code. For what I was measuring (RO system efficiency), it didn't seem incredibly accurate over long periods of time.

Also, with those flow sensors (I have the Swissflow ones), there is a little propeller in there that looks like it would get destroyed by any grain husk or hop leaf it might encounter.

I would consider a method similar to the Blichmann Autosparge or the MoreBeer sparse thing. Those basically keep a certain level of liquid on top of the grain at all times.

jpalarchio said:

I would consider a method similar to the Blichmann Autosparge or the MoreBeer sparse thing. Those basically keep a certain level of liquid on top of the grain at all times.

Click to expand...

This sounds like a pretty good solution.

You could put a adjustable height thermocouple submersed, assuming the temp would change when no longer submersed.

grathan said:

You could put a adjustable height thermocouple submersed, assuming the temp would change when no longer submersed.

Click to expand...

Yes, that might work, also a adjustable current probe setup would work - I've worked on tanks that had probes with small voltage on them - when the liquid touched them, they sensed the level.

You could use a liquid level switch just above the heating element ( if you have room between the false bottom and the element).
Like this: http://www.usplastic.com/catalog/item.aspx?itemid=100829

I was thinking about going this route, but right now I'm using a reverse flow setup with a second vessel.

OP was talking about recirculating the MLT. Perhaps a mechanical float switch would gunk up with grain and get sticky from wort.

aamcle said:

If I recirculate through a grain bed, in at the top, out at the bottom, through the pump and back in at the top a simple closed loop.

If the flow through the bed was too slow then the pump would suck all the wort from under the grain be and could be damaged....

Click to expand...

If that is happening then air has to be is getting in somewhere, as it should be impossible to do otherwise.

I do the same thing as you and it' impossible to suck wort from under the MLT false bottom without new wort being introduced from above the false bottom.

So the only two possibilities should be: Constant flow, or stopped flow (pump is off, or false bottom is clogged).

So before looking for a solution that involves liquid sensors as a bandaid solution, I'd fix the problem at the source.

Or maybe i'm not understanding your setup?

Kal

kal said:

If that is happening then air has to be is getting in somewhere, as it should be impossible to do otherwise.

I do the same thing as you and it' impossible to suck wort from under the MLT false bottom without new wort being introduced from above the false bottom.

So the only two possibilities should be: Constant flow, or stopped flow (pump is off, or false bottom is clogged).

So before looking for a solution that involves liquid sensors as a bandaid solution, I'd fix the problem at the source.

Or maybe i'm not understanding your setup?

Kal

Click to expand...

There was a thread a few months back about a bent up FB due to a stuck sparge and the pump sucking enough to pull the grain down onto the FB enough to bend it. I think this and cavitating the pump is the main reason for this safety feature. I agree that you would not likely see "air" under the FB but more the FB collapsing/crushing.
Using a grant with a hi/low level switch control of the pump would be the surefire method.
Or a pressure sensor that cuts the pump out if it senses a low pressure under the FB.