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Flowmeter vs flow switch


(@basline)
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Joined: 3 years ago
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I'm planning to overhaul/replace my kal clone control panel with something much more conducive to automation and was very excited to discover that BrunDog and augiedoggy were collaborating on a software solution.

I still have some decisions to make, but and looking at doing a Quadzilla and resurrecting my RIMS tube (moving to a new place where I'll have access to 50amps again). I'd like to tied some sort of flow sensor to the power on the elements, and I'm curious to hear your thoughts on using a flowmeter vs a flow switch if you are willing to share.

For a flow meter, I'm considering as swissflow sf800 as it sounds like the adafruit unit isn't terribly reliable and could be a finicky way to determine if the element is firing dry.

For a flow switch, I'm looking at an all stainless model that augiedoggie posted on HBT ( https://www.ebay.com/itm/Liquid-flow-switch-sensor-NPT-1-2-inch-female-female-Stainless-Steel-FSS-N1FF-SS-/222859334294?oid=222638041158).

I originally had just been planning to do a flow switch, as right now I don't have a need to know the flow rate on my RIMS tube. But I've been worried about debris clogging the flow switch, and was wondering if I'd have better luck with a flowmeter as I think the turbine is a smaller profile.

Any input would be much appreciated.


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(@pbruno3)
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Joined: 5 years ago
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I think your line of reasoning is sound, but I would go with a FM over a FS. If it fails, it will still report zero and maintain safety on any downstream devices or processes. Plus you will get more data to help you understand the mash status and feed other automation sequences like fly sparging, etc.

That swissflo sensor might be too small for a chugger or March size HB pump. They will go upwards of 7 GPM so that might be restricting. The cheap adafruit sensor I have personally used has been remarkably reliable but there are certainly many better at higher costs. 

BTW, RIMs should be mounted vertically, and if done this way with a temp probe at the top, even if flow is stopped and the element is commanded by the PID to be on, the heated fluid rises and warms thebsensor, hence turning off the element - so stopped flow isn’t to be feared in a RIMs system!


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(@basline)
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Joined: 3 years ago
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Thanks for the response. I'd been going back and forth about a plastic flowmeter and not knowing what the material it is made from.

It looks like there is a glut of used IFM stainless magnetic flow meters on ebay right now. The wetted parts are stainless steel 316L, PEEK (which I understand is generally food safe), and Viton. I picked up this unit:  https://www.ebay.com/itm/323287910090 for a pretty reasonable price. May fall a little short of the highest possible flow on my chugger pump, but my plan is to move to a tops flo td5 with PWM and copy your "auto-mash" approach eventually.

Thanks for the input.


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(@pbruno3)
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That is a super-sweet sensor. I looked into them a while ago but held off for some reason (can't remember if it is flow range, fittings, or pulses/volume). 

That last unit is very important depending on what you want to do. On my personal brewery, I fly sparge on demand, and the incoming water flow rate at 1 qpm needs to have pretty good resolution, else the results are very course. For example, the current plastic FM is about 16 pulses/second at 1 qpm. That means if it drops down to 15 the reading is 0.94 qpm, which is a 6% drop... so resolution less than or more than 6% can't be measured. Therefore, in this application, a higher pulse rate per volume would be helpful. I don't remember the spec for that sensor.

Report back and let us know how it works out!


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(@basline)
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Joined: 3 years ago
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It does look pretty sweet. It outputs a current loop (4-20mA), and you can calibrate what corresponds to 4mA vs 20mA. So you could in theory up the resolution on the range of flow your most concerned with.

Unfortunately, it maxes out at 6.6 gpm, but I doubt that will be a big issue on my mash. 

It'll be a bit before I have it running (we're about to move, and a new basement brewery is going to take a bit). But I'll report back when I'm up and running, and I'll definitely have other questions about integrating bits into BruControl.


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(@thesleepydog)
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Joined: 5 years ago
Posts: 9
 

I just checked out the spec sheet of that sensor because is looks good and it will operate to 70degC.

http://www.ifm.com/products/us/ds/SM6004.htm

So Sparging might be an issue at 75degC...


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(@pbruno3)
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I think ~7 GPM is plenty - a regular brewing pump doesn’t do much more than that with zero lift. Also 70 deg C threshold should be ok. Either go up to 75 and live with a little inaccuracy or just sparge a tad cooler. The 4-20 mA output can be integrated easily enough but you won’t get a totalizer unless you do some creative integrating math in a script. The counter (pulse output from the sensor) would be an easier path to get both current flow and total.


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