Sawdustguy

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If the tube empties it's gonna get real hot in that tube real fast. The temperature probe will read that and and as soon as the temperature goes above the alarm setting the PID relay will open therefore breaking the connection from the PID to the SSR. That will turn off the element. I am from the better safe than sorry school so I use both the alarm relay and flow switch.

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Guy

Brewery URL: Black Dog Brewery NY

BBQ Team URL: Two Fat Polocks BBQ Team

Sawdustguy

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I just found out mine does also but you have to make sure they are low density.

__________________
Guy

Brewery URL: Black Dog Brewery NY

BBQ Team URL: Two Fat Polocks BBQ Team

Ohio-Ed

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Well, I agree the element is gonna get really hot really quick, but I don't know if the air in the tube would transfer the temp to the probe quick enough to save the element?

I agree if you got it you might as well use it... just not sure I would depend on it to do the job.

Reelale

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That's my concern as well. What is the fail-safe, other than making sure you have flow?

Ohio-Ed

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I tested mine as if I had a stuck mash by closing the valve and completely stopped the flow...
I use a BCS460 and the control, caught the temp before it reached 170f. (It spiked about 10f above the setpoint) That is out of the box setup (I can't take credit fur tuning), I'm not sure an Auber PID would do the same, the other thing is that my tube is 2" in diameter so it has a fairly large volume to "dampen" the temp spike.

What I haven't tested is what happens if the tube drains... say a hose breaks???

I think you HAVE to make sure that the tube will not empty from a siphon or something... my input is lower than the output and both are well below the level of the mash in the mash tun.

A flow switch on the output of the rims should work... But most I have seen don't seem to be rated very well for particulates in the flow... so, I don't know??? I don't have one, but I'm interested to see how it works out. (I know SawDustGuy has a flow switch, but I don't know the specs on his or if he has tested it with wort)

You can see the spikes in this graph where I closed the valve, then the temp leveled off to setpoint (157), then where I opened the valve back up. (The setpoint was 130 the first time I closed the valve)

Reelale

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I'm very interested in the flow switch design. It looks like your's behaved well, if I am reading the graph right. Never did exceed 170F. That's good, no?

Ohio-Ed

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Yes, I am very happy with the way it behaved. The fear was that it would almost immediately boil the wort in the tube, turn it to steam and empty the tube which would expose the element to a dry fire.

Reelale

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I'm very much hoping that a PID will react the same. If it does, I can live with that, along with a visual check of wort flow. I still would like to see a design/wiring for a flow switch

ScottSA

Recipes 

i know this is the RIMS for Dummies thread, so its okay to ask this...

Whats the difference between HD and LD elements? is there a way i can tell by looking other than it saying so?

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South Texas Brewing Co

Ohio-Ed

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HD, LD and ELD (extra low density, I think) are the choices.
What it relates to is the surface area of the element that the heat is generated through... so basically how hot each square inch of surface becomes.

A larger element with the same watt rating is going to be a lower watt density.

So without a label, or another element to compare, I don't know anyway you can tell by looking. If you are looking at a local store, you might be able to find more info available for the element on-line.