HLT Low Water Alarm/shutoff

[dtfeld]

I've blown a couple heater elements in my HLT by running it partially submerged or dry. Stupid. I want to put a little automatioin on it, but want some input.

I currently have a 10 gal cooler, so I thought about epoxying a capacitive prox to the inner wall and tuning it to "see" the water behind it.

However, going to an all SS 10 gallon system, and a capacitive prox won't work thru a metal wall. I'm thinking about something on a sight glass, but finding something small enough and mounting issues are problematic. I thought I could wire it in series with the main power heater relay to interupt power to the heating element if water goes below the set level.

Has anyone added this safety feature? What did you use and how did you wire it in? As always, pitures appreciated.

 

[IrregularPulse]

You want a float switch wired in series with your control signal from the PID to the SSR.

 

[Cpt_Kirks]

I never run the elements in my HLT when the drain valve is open. If you follow that rule, maybe some kind of switch connected to the valve?

ETA: Also, I have seen a two probe water level sensor that uses the metal pot as the common. I will look for the link when I get home.

 

[dtfeld]

Float switch... Interesting. Have you sourced a food grade version?

Also, was trying not to have to cut another mounting hole in the thing. Prox switches are a "shoot through" solution.

 

[bruin_ale]

I never run the elements in my HLT when the drain valve is open. If you follow that rule, maybe some kind of switch connected to the valve?

ETA: Also, I have seen a two probe water level sensor that uses the metal pot as the common. I will look for the link when I get home.

Do you fly sparge? You don't lose heat during that? I haven't got my system up yet, but fully intend to run the HLT element while sparging to keep the temp of the sparge water where I want it. On my old propane system I only had a single burner, so while I was sparging I would move the burner to my boil kettle and get the boil started. By the time I was done sparging, the sparge water was probably 110-120 degrees at best.

 

[bruin_ale]

Float switch... Interesting. Have you sourced a food grade version?

Also, was trying not to have to cut another mounting hole in the thing. Prox switches are a "shoot through" solution.

http://www.oscsys.com/Stainless-Float-Switch.html

I think I've seen the same on e-bay for about $10..

 

[IrregularPulse]

Float switch... Interesting. Have you sourced a food grade version?

Also, was trying not to have to cut another mounting hole in the thing. Prox switches are a "shoot through" solution.

as in shoot through the wall of the cooler and detect water level? I admit I have limited experience with them, but have worked with them in the field and have never seen an application where a proximity switch shoots through a wall and sees something. It would see the wall and register. (In my limited experience)

 

[IrregularPulse]

This one appears to be used in coffee urns so I would say food safe and likely temperature cooperative. Not a lot of info on it but you could probably get more details by contacting them.

 

[IrregularPulse]

http://www.oscsys.com/Stainless-Float-Switch.html

I think I've seen the same on e-bay for about $10..

Wow cool find. You can get a dented (damaged) version for $8.99

 

[carloski44]

This maybe what your looking for Kind of pricey at $135.00 from Automationdirect.com
http://www.automationdirect.com/static/specs/prox30mmuhz.pdf
A ultrasonic proximity sensor can measure fluid levels from the top down, would make a great little addition to an HMI screen to show liquid level in the HLT.
Let me know if you go that route how it works out for you I have played with them a little here and there but never actually used it in a application.

 

[weirdboy]

This maybe what your looking for Kind of pricey at $135.00 from Automationdirect.com
http://www.automationdirect.com/static/specs/prox30mmuhz.pdf
A ultrasonic proximity sensor can measure fluid levels from the top down, would make a great little addition to an HMI screen to show liquid level in the HLT.
Let me know if you go that route how it works out for you I have played with them a little here and there but never actually used it in a application.

I don't get how you could measure fluid levels using that, without using a whole bunch of them lined up in series. Does it return a gradient voltage or current based on the proximity?

 

[IrregularPulse]

This maybe what your looking for Kind of pricey at $135.00 from Automationdirect.com
http://www.automationdirect.com/static/specs/prox30mmuhz.pdf
A ultrasonic proximity sensor can measure fluid levels from the top down, would make a great little addition to an HMI screen to show liquid level in the HLT.
Let me know if you go that route how it works out for you I have played with them a little here and there but never actually used it in a application.

I've helped used something similar in a CAT plant to position an end mill on an engine block. It wasn't for liquids, but it was pretty neat. Extremely accurate. Quite a bit of overkill for this scenario.

*EDIT* I did not look at the link and assumed it was something else. The one we used was a single sensor that bounced a signal back to determine distance.

 

[Cpt_Kirks]

Do you fly sparge? You don't lose heat during that? I haven't got my system up yet, but fully intend to run the HLT element while sparging to keep the temp of the sparge water where I want it. On my old propane system I only had a single burner, so while I was sparging I would move the burner to my boil kettle and get the boil started. By the time I was done sparging, the sparge water was probably 110-120 degrees at best.

I batch sparge.

When I'm ready to sparge, I add half the water and recirculate for a while. Then, after it drains, I add the other half. If I need to bump up the heat, I just turn the elements (heatsticks) back on in between halves.

I'm going to add a layer of reflectix insulation to the HLT, which will help with any heat loss.

 

[Cpt_Kirks]

ETA: Also, I have seen a two probe water level sensor that uses the metal pot as the common. I will look for the link when I get home.

Found it: http://www.wortomatic.com/articles/The-Liquid-Level-Doctor

 

[carloski44]

You would only need 1 per vessel as it is analog, you would mount in the lid of your HLT, and you would need a analog input in order to read the sensor. In other words its not acutally a switch it is a analog measuring device like a thermocouple or pressure feedback, and could still function as a switch when certain levels were reached, but could also function as a level indicator when coupled with an HMI or similar device.

 

[IrregularPulse]

You would only need 1 per vessel as it is analog, you would mount in the lid of your HLT, and you would need a analog input in order to read the sensor. In other words its not acutally a switch it is a analog measuring device like a thermocouple or pressure feedback, and could still function as a switch when certain levels were reached, but could also function as a level indicator when coupled with an HMI or similar device.

You linked a set of Thru-beam Pair sensors. You need both.

 

[carloski44]

This one works a little different it is ultrasonic.
If he is willing to drill another hole this switch looks pretty cool and is what some others are using now. https://www.homebrewtalk.com/f170/i...ents-while-now-204412/index2.html#post2394717

 

[carloski44]

Yep, just grabbed the cheapest one, happen to be the through beam sensor. here's the link to the single sensor but quite a bit more expensive. http://www.automationdirect.com/static/specs/prox18mmultrasu.pdf

 

[Walker]

http://www.oscsys.com/Stainless-Float-Switch.html

I think I've seen the same on e-bay for about $10..

Awesome. Thanks for the link.

I snagged one of the dented ones. The rest of my system is ugly, so why not continue the theme?

 

[Mirilis]

If you dont want to put anymore hols in your kettle, why not just mount a float switch to a piece of tubing (stainles or acrylic if your cheap). Then just mount it to a cross that covers the opening. With that you could be in it for pretty cheap.. (less than 15 bucks if you use PVC cross, acrylic tube, and cheapo float switch. )

 

[dtfeld]

http://www.ia.omron.com/data_pdf/data_sheet/e2k-l_ds_csm459.pdf

Found what I was looking for... I'd use 2 of these, one for a low water alarm/light and a second lower on the sight glass to cut power to the element.

These are strap on and I'd have to see if they would fit on a 20 gal blichmann.

No Holes, but they are probably pretty expensive. Ill have to look at automation direct to see if they have an equivalent.

 

[dtfeld]

Found a couple on eBay fir $20/apiece. I bought them now well see if the fit. Worst case I realist on eBay

 

[carloski44]

Those are the bee's Knees, if they work as listed. Had no idea they existed. Let us know how you make out with them.

 

[dtfeld]

The problem I see is 1) physical size...will it fit? 2). There are space requirements behind and to the side of the sight glass...hope the don't "get confused" by the pot and sight tube protector

I'll report back.

Update: I measured the blichmann 20 gal Sight glass protector. Looks like its about 23mm inside edge to edge, so I think the 20mm version will strap right on and hopefully give me a nice easy clean solution. I post pics when I get the units in.

 

[IrregularPulse]

http://www.oscsys.com/Stainless-Float-Switch.html

I think I've seen the same on e-bay for about $10..

Picked one of the dented ones up for $14.95 after shipping. It is NC contacts, but you can flip the assembly upside down to make a NO like we would need.

 

[dtfeld]

Received parts today. Unfortunately, the sensor is about .5 mm too wide...damn. Have to re-evaluate.

They'll certainly work on a stand alone sight tube though.

 

[MadViking]

I don't know, but just another thought here, two small (18 gauge) solid (not stranded) wires with only the insulation stripped off the first 1/4" of each end can be pushed through the sight glass to your heating element cut off level (stagger the wires so that one is lower than the other so the stripped ends can't touch) and these wires can be hooked up in series on the control wire that activates the relay that turns on your heating element. The wort acts like a conductor. Just a thought.

 

[bruin_ale]

that's interesting.. my espresso machine uses something similar to that I think, there's just a piece of metal in the fill tank that when the water level drops below that point the machine goes to sleep until you fill it up.

 

[Walker]

I'm pretty sure that would trip your GFCI. If the wort conducts, the a path from those wires to ground would exist via the groud wire on the kettle (which is also touching the wort).

 

[bruin_ale]

I'm pretty sure that would trip your GFCI. If the wort conducts, the a path from those wires to ground would exist via the groud wire on the kettle (which is also touching the wort).

HHmm.. yeah, that's true.. guess that's probably not how my espresso machine works