Home Brew Forums > Home Brewing Beer > DIY Projects > Other > Constant gravity measurement idea
LinkBack Thread Tools
Old 11-16-2012, 07:38 PM   #1
Feedback Score: 0 reviews
Join Date: Jul 2011
Location: Richardson, Texas
Posts: 977
Liked 46 Times on 36 Posts
Likes Given: 3

Default Constant gravity measurement idea

I think it might work to dangle a float into the center of the fermenter on a piece of fishing line. This would require being able to measure the very small downward force, to calculate the buoyancy change. Ideally, I would be able to read the gravity with a microcontroller, but a mechanical/visual scale would also be sufficient.

I can't think of a sensor that would work for this and also be usable.

Maybe it would work to hook the fishing line to a long lever to multiply the force and then a standard strain gauge would be able to register.

BetterSense is offline
Reply With Quote Quick reply to this message
Old 11-16-2012, 09:31 PM   #2
Feedback Score: 0 reviews
Join Date: Sep 2011
Location: San Diego, CA
Posts: 347
Liked 36 Times on 29 Posts
Likes Given: 1


The biggest problem I see with this is krausen buildup on your float. At my last job I worked on some wireless issues on a set of fermentation controllers at UC Davis and they had originally tried this with wine and it didn't work due to the second main problem - CO2 bubbles sticking to the float. They ended up implementing a system using a differential pressure sensor with each end mounted at different heights in the fermentor. The larger the change in pressure resulted from a higher specific gravity. For this to work however they did have to continuously pump a small amount of air into both of the sides of the pressure sensor similar to how the brewtroller level sensors work. Seeings how they were fermenting 40 gallons or so in one fermentor they didn't run into problems oxidizing the wine, but on a homebrew scale I don't see how you could get away with this without contamination or oxidization issues.

crane is offline
Reply With Quote Quick reply to this message
Old 11-16-2012, 10:06 PM   #3
Waste Allocation Load Lifter - Earth Class
Feedback Score: 0 reviews
passedpawn's Avatar
Join Date: Apr 2009
Location: ☼ Clearwater, FL ☼
Posts: 20,486
Liked 3977 Times on 2441 Posts
Likes Given: 3423


You can measure gravity from inside the wort, not at the top. Put a piece of bouyant (i.e., sp.gr. < 1) on an arm and measure the angle that it hangs at. A little accelerometer device (I like the ST Micro devices) can easily measure this.

The device needs a level bubble to be held exactly level inside. Hold it inside with a magnet on the outside.

Transmit the gravity with RF (lots of simple small solutions there) to a display on the outside. Maybe the "holding" magnet and the simple display are on the same assy.

I use something similar for my saltwater fish tank.

- Andrew
passedpawn is offline
Reply With Quote Quick reply to this message

Quick Reply
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Bottling without a gravity measurement hiphops Bottling/Kegging 4 10-30-2010 10:03 PM
constant gravity reading wacko General Techniques 2 10-02-2010 08:03 PM
pre-boil gravity measurement - cool first? bdaddy Beginners Beer Brewing Forum 3 08-16-2010 02:59 AM
Crazy idea: constant flow brewing dantose Other 6 08-04-2009 07:35 PM
Gravity Measurement Aspera Equipment/Sanitation 0 02-11-2009 01:51 AM

Newest Threads