Load cells?

How about 'em? I'm wondering what it would take to put load cells under the BK, HLT, and MLT to measure my brew process. I use a stick with notches, and I have seen others with sight glasses and float switches interlocked with pumps and electric elements.
A quick calculation using a refractometer can convert weight to volume without adjusting for temperature, and I'm pretty sure more accurately than a sight glass or a notched dowel could.
I think I could interlock a minimum weight with the element, like a float switch without the kettle penetration, to keep from dry firing, and more easily measure strike water or preboil weight (i.e., vol), trub loss, etc. I'd have to convert from Beersmith's volumes, but that would be easy enough.
Unfortunately, I have no idea how one would do this, but it seems like a cool idea.
So, the question is, does this have any merit, and how could it be done?

Well load cells work by monitoring a change in resistance caused by flexing of a structure with carefully arranged wires carrying current.

I would hazard a guess that you will have trouble getting accurate readings unless you can keep the load cells themselves at ambient temperatures, otherwise I would expect that the readings will vary depending on the temperature they experience.

PeteNMA said:

Well load cells work by monitoring a change in resistance caused by flexing of a structure with carefully arranged wires carrying current.

I would hazard a guess that you will have trouble getting accurate readings unless you can keep the load cells themselves at ambient temperatures, otherwise I would expect that the readings will vary depending on the temperature they experience.

Click to expand...

I was thinking I'd have to build a frame to mount the load cells and a platform for each kettle, which would have to be insulated. Maybe a silicone mat on a wood platform.

PeteNMA said:

I would hazard a guess that you will have trouble getting accurate readings unless you can keep the load cells themselves at ambient temperatures, otherwise I would expect that the readings will vary depending on the temperature they experience.

Click to expand...

Bridge strain gauge load cells are probably the most common method of measuring loads in industry. They are accurate at all temperatures (or within a reasonable range anyway). I have them under my mash tun/kettle though they are not used in automatic system (one under each of the four legs of the stand). They are combined in a box with readout which could, of course, contain an ethernet, USB or serial interface. I don't recall what this box has, if anything, because I don't use it other than as a scale.

It probably matters less at higher weights. We have mostly analytical micro and ultramicro balances at work which have to be recalibrated if they get moved into the high temperature dial up chambers.

But then those are weighing down to six decimal places. Load cells that can take several kilos of weight are likely less sensitive.

How are you using your setup AJ? The same sort of idea that the OP described to measure volumes? How do it work for you? Certainly appeals to the more analytically minded side of me

The main use I put it to is preparatory to mashing. If I need 30 gal of water I tare the load cells and then admit water until I read 249 lbs. At the end of the boil I check the SG using a Plato hydrometer which, from the weight of wort, gives me the extract and efficiency right away.

ajdelange said:

The main use I put it to is preparatory to mashing. If I need 30 gal of water I tare the load cells and then admit water until I read 249 lbs. At the end of the boil I check the SG using a Plato hydrometer which, from the weight of wort, gives me the extract and efficiency right away.

Click to expand...

I think this ^^ along with more accurately measuring grain absorption, trub loss, etc for different recipes is the biggest benefit. With a single vessel BIAB, I could get all these measurements in one readout.

daveMN said:

I think this ^^ along with more accurately measuring grain absorption, trub loss, etc for different recipes is the biggest benefit. With a single vessel BIAB, I could get all these measurements in one readout.

Click to expand...

You'll need to get into some serious calculations to make those additional measurements you mention. Do you know how to do them?

Brew on

doug293cz said:

You'll need to get into some serious calculations to make those additional measurements you mention. Do you know how to do them?

Brew on

Click to expand...

The inputs would be
- weight of strike water
- weight of grain
- weight of kettle
- weight of preboil
- weight postboil
Grain absorption: ((Strike - Preboil) / 8.35 lbs/gal) / Grain
Trub loss: Postboil - Kettle with Trub

Am I thinking too simply about these calcs?

You Might Considering Using a Pressure Transmitter For Level Control, I Used Them From 15-5000 Gallon /Vessels/Tanks
If your not interested, right now w/analog 4-20ma output signal and just a visual digital LED display look into on Ebay/Used
IMF Efector Pressure Transmitter or Rosemount Pressure Transmitter.

Later On, You Implement Automation, The 4-20ma Signal Is Available.
All Efectors Have LED Display, No External Hardware Required For Programming, Some, After Setting Set-Point Control a N.O. Output,
Others Have Analog Output.
The Rosemounts, Some Have No Display, Only Analog Output, Some Models, Display Can Be Added Later Onto Transmitter.

Use The Pressure Transmitter For Vessel/Tank Level, Can Be Setup For H20" or Psig Display, Just Mount Sensor Inlet Equal To/or As
Near As Possible To Tank Lowest Point. Iam Currently Using The [Older]Rosemount 3051C, Have Exceeded 225Deg For Extended
Testing Periods w/o Sensor Failures As Well In an Industrial Settings.
For The Rosemount, Under The Stainless Steel Top Plate/External, There Are 2 Buttons To Program, Otherwise Consider Using a
Older Version Handheld Communicator Like The HART 268, Which Most People Have No Use For (Ebay) Last HART 268, I Paid Aprox $30.00
Anyone Selling These On Ebay For Higher$ Might Not Realize, They Are Not Used In The Industry Much/Anymore +15Yrs
Take Your Time On Ebay, You Will Finally Find The $-Range Best For You.

daveMN said:

The inputs would be
- weight of strike water
- weight of grain
- weight of kettle
- weight of preboil
- weight postboil
Grain absorption: ((Strike - Preboil) / 8.35 lbs/gal) / Grain
Trub loss: Postboil - Kettle with Trub

Am I thinking too simply about these calcs?

Click to expand...

I forgot to add adjustment for the SG of the Pre-/ Post-boil weights to compare these apples-to-apples as weight of water.

daveMN said:

I forgot to add adjustment for the SG of the Pre-/ Post-boil weights to compare these apples-to-apples as weight of water.

Click to expand...

Yeah, I was going to mention the SG correction. For grain absorption I get:8.3374 lb/gal is the density of water at 60˚F, and since your hydrometer is calibrated at 60˚F (most likely), you should correct all volumes to 60˚F.

For trub loss I get:This won't be completely accurate, as the trub will contain excess volume from the hops & break, and its SG will be slightly higher than the Post-Boil_SG.

Brew on

Would I still use the 60 degree density if I'm using a refractometer with ATC?
I wonder if I could use a hydrometer on a trub sample?

daveMN said:

Would I still use the 60 degree density if I'm using a refractometer with ATC?
I wonder if I could use a hydrometer on a trub sample?

Click to expand...

If you're going to use a refract, then you need to calibrate it against your hydrometer and determine the proper wort correction factor. Then, since you calibrated against a hydrometer calibrated at 60˚F, you still want to correct volumes to 60˚F. If you happen to have one of the minority of hydros calibrated at 68˚F, then the water density to use is 8.3304 lbs/gal.

Brew on

doug293cz said:

If you're going to use a refract, then you need to calibrate it against your hydrometer and determine the proper wort correction factor. Then, since you calibrated against a hydrometer calibrated at 60˚F, you still want to correct volumes to 60˚F. If you happen to have one of the minority of hydros calibrated at 68˚F, then the water density to use is 8.3304 lbs/gal.

Brew on

Click to expand...

The difference shouldn't be significant though. At 5 gals, the difference between 8.35 and 8.33 is 0.1 lb, or 0.2%. That's probably around the error on the load cells. That, or equal to the other spills, drips, or losses during a normal brew day.