Liquid Sensor

I have looked around for some sort of sensor i can wire up to indicate liquid presence in a RIMS tube. I am trying to design a failsafe indicator to keep from dry firing the element. Has anyone looked into and or done this before?

Just throwing this out there , I have no experience with what you are looking for , but I have seen a floatless sump pump that used two liquid sensors to turn on and off. Maybe this will steer you in a direction you are looking for.

power sorce with and in line led and 2 leads in side the tube. water, wort, liquid conects the leads lighting the led.

I was thinking something food grade that could stand up to PBW. I want it to be a power up fail safe for the PID. Ie with a relay PID can't send a power signal to the element without a positive liquid reading in the tube.

I'd think detecting flow is safer, than level. Googles for liquid flow sensor. The industry I retired from used IFE brand flow sensors, they were a SS probe 1/4 dia. about 1/2" long with pipe threads for easy installation. The theory of operation was a thermistor in the tip of the probe that would cool slightly with fluid flowing and an adjustable detector circuit to set a minimum flow threshold based on the temp. drop. It was a 3-wire device in a pretty small package.

I think the concept of flow sensor idea would work however as the liquid would be at varying temps it is likely to throw off a cooling effect type sensor which may cause it to switch off in the middle of your brew. If you had a pressure sensor at an location of the pipe just in front of where there is a restriction to the flow then this would show a change in pressure when the liquid was flowing. air flow would not provide any significant pressure to the sensor.

Clem

The temperature range of mashing is what makes me think i need just some sort of liquid presence detector. can anyone think of any probes that could be jurry rigged for the purpose? i would need a SS probe that is insulated from the RIMS tube. i could thread two of them right next to each other and that would allow for electrical continuity, trip SS relay and presto.

How about a sight port, from McMaster-Carr? They come in different metals and sizes, so you should be able to pick one that you like. You might want to look at the ones with reflectors since those could make it easier to see what's inside the tube.

Tie the heating element into the same circuit as the pump using a relay. If the pump isn't running, the heating element can't come on.

The flow sensor I'm referencing only reacted to the relative temperature difference between flowing and static liquid, the actual fluid temperature had no effect on detecting flow. That design feature and no moving parts tremdendously increased reliability over standard paddle type flow switches. Not sure which would be worse only detecting level in a rims tube, failed element or steamed mash.

Two leads in the output of the rims tube in series with the dc voltages for the ssr. No flow through the rims tube heating element won't fire. House it all in plastic and you should be fine it's the same thing we use in the navy for sprinkler alarms for magazines and such never fails.

It's messy but something like that

The flow of wort completes the circuit allowing the element to switch

I built an electromagnetic flow sensor to do this. They are nice because there is nothing poking into the liquid and the temperature doesn't really matter.

I haven't integrated it into the brewery yet, but it worked pretty well on the bench. The idea is to have the flow in GPM displayed on the RIMS controller, and integrated into the heat controller to prevent dry firing / scorching.

It does require a custom PC board, and kind of a tricky one at that due to the very low signal levels coming in. Boards are kind of my thing though..

RelentlessJ - this is exactly what I was thinking. I am trying to find something off the shelf or even something I can built for this purpose. I am always looking for the KISS approach to this hobby.

I am assuming you are using a non-conductive hose or tube as the return line from the RIMS device. You could place two short sections of conductive tubing (copper or stainless steel) in the return line. Separate them by a couple of inches with your non-conductive return tubing. Simply solder the DC current leads to the conductive tubing and you're all set. You should have no leaks and plenty of contact area for sensing the presence of whatever liquid you are hoping to detect.
You could even place one detector at each end of your RIMS tube. This would help to insure there is liquid filling the RIMS tube. The conductivity of the liquid between the sensors may become an issue the further apart they are placed.

If you're interested in the flow sensor idea, futurlec has some high-temp sensors that might do the trick.

Flow Sensor

I picked up a couple of them a few months ago, but I haven't integrated them into the system yet. I need to make it through a brew day with my new system without making some bonehead mistake before I start adding more automation to the system...maybe what I really need is to start adding alarms instead of automation.

If you're interested in the flow sensor idea, futurlec has some high-temp sensors that might do the trick.

Flow Sensor

I picked up a couple of them a few months ago, but I haven't integrated them into the system yet. I need to make it through a brew day with my new system without making some bonehead mistake before I start adding more automation to the system...maybe what I really need is to start adding alarms instead of automation.

bblack7489 said:

If you're interested in the flow sensor idea, futurlec has some high-temp sensors that might do the trick.

Flow Sensor

I picked up a couple of them a few months ago, but I haven't integrated them into the system yet. I need to make it through a brew day with my new system without making some bonehead mistake before I start adding more automation to the system...maybe what I really need is to start adding alarms instead of automation.

Click to expand...

Those all look like the operating temperature range is way too low for a RIMS system.

kickrjason said:

Those all look like the operating temperature range is way too low for a RIMS system.

Click to expand...

Granted, I don't know what the typical outflow temp is from a RIMS tube, but is it really greater than 178F?

And realistically, looking at the materials it would probably be ok up a little above the 80C rating. My guess is that the temp range is a function of the operating pressure, and since it's rated to 1MPa it would be ok at a higher temp in the pressure range of your brewery.

Either way, I'm not worried about it and am going to use it in my HERMS system, but you're obviously free to make your own informed decision.

How do you use the output? I'm looking at the datasheet. It has a different "pps" for different flow rates. Pulses per second?

It doesn't look like a simple "flow=switch closed, no flow=switch open" device to me.

chuckjaxfl said:

How do you use the output? I'm looking at the datasheet. It has a different "pps" for different flow rates. Pulses per second?

It doesn't look like a simple "flow=switch closed, no flow=switch open" device to me.

Click to expand...

Thats exactly what i was just reading. This is way more elaborate then what i am looking for. I don't need to know the volume or rate, just liquid yes/no.

chuckjaxfl said:

How do you use the output? I'm looking at the datasheet. It has a different "pps" for different flow rates. Pulses per second?

It doesn't look like a simple "flow=switch closed, no flow=switch open" device to me.

Click to expand...

You're right. It outputs a digital pulse train and the number of pulses per second gives you the flow rate.

I currently using a Gem flow sensor on mine works perfect. I have it in series with the ssr signal. I can just shut the pump down and not have to worry about the heater firing unless it sees .5gal/min or more.

Look Here

Jbt said:

I currently using a Gem flow sensor on mine works perfect. I have it in series with the ssr signal. I can just shut the pump down and not have to worry about the heater firing unless it sees .5gal/min or more.

Look Here

Click to expand...

NSF rated, SPST, good to 150PSI@212F, 1/2" NPT...Perfect!

But.. $87.00!? Am I the only one suffering sticker shock on that one?

What is the main threat of blowing an element that's contained in a RIMS tube? Just the property loss of the $20.00 element? or is the risk of electrocution if the element were to dry fire and damage itself pretty real?
I KNOW the risk is always present, but how real is it in the actuarial sense?

chuckjaxfl said:

NSF rated, SPST, good to 150PSI@212F, 1/2" NPT...Perfect!

But.. $87.00!? Am I the only one suffering sticker shock on that one?

What is the main threat of blowing an element that's contained in a RIMS tube? Just the property loss of the $20.00 element? or is the risk of electrocution if the element were to dry fire and damage itself pretty real?
I KNOW the risk is always present, but how real is it in the actuarial sense?

Click to expand...

I got a .5 on eBay for $16.. Also the .25 I have I think I paid around $23 from somewhere. Look around I'm sure you can find one a lot cheaper.

How about this...?

I found some used on ebay for about $20.00 These are 24 VDC. These are intended to be connected to a PLC, so you may need a small relay to get it to do what you want, but they work like a champ. Just need to be attached a short section of clear pipe.

I'm using them on my HLT to prevent dry firing and a auto-fill cutoff if/when I add automated valves.

Jbt said:

I got a .5 on eBay for $16.. Also the .25 I have I think I paid around $23 from somewhere. Look around I'm sure you can find one a lot cheaper.

Click to expand...

This one is $15 .25 flow actuation

chuckjaxfl said:

NSF rated, SPST, good to 150PSI@212F, 1/2" NPT...Perfect!

But.. $87.00!? Am I the only one suffering sticker shock on that one?

What is the main threat of blowing an element that's contained in a RIMS tube? Just the property loss of the $20.00 element? or is the risk of electrocution if the element were to dry fire and damage itself pretty real?
I KNOW the risk is always present, but how real is it in the actuarial sense?

Click to expand...

Found the FS-4 on ebay for $24.90.

http://www.ebay.com/itm/Gems-Sensor...183?pt=LH_DefaultDomain_0&hash=item4cf74222ff

How about a simple moisture meter? They can be had for $10-$15. Take the casing off and wire it into your system. I've used them for similar purposes before. If all you want to know is whether you have liquid present or not, then there's no need to get any fancier than that.

stlbeer said:

Found the FS-4 on ebay for $24.90.

Gems Sensors FS-4 Liquid Flow Switch 181417 | eBay

Click to expand...

That one is only .05/gal min actuation.
I really would not recommend that one. I bumped mine up to a .5/gal one from .25 because I really don't want my flow to be under .5/gal min with the element on.
With one that is .05. If the flow rate slow from grain issues the element will probally still be on with the turbulance of the pump.

Wort-O-Matic: The Liquid Level Doctor

This could be modified to work when liquid was present