Homebrew monitor

[jammers]

Hi there,

I work for a research group that designs environmental sensing equipment. I've recently started getting into homebrew (having grown up with my dad always making some) my first batch went quite well and I'm moving on to make my second. I thought I would quite like to monitor what's going on in my brewbin and the cupboard it lives in.

Monitoring the temperature of the room and brewbin is easy, however I want to measure the spesific gravity of the mixture.

Digital hyrdomiters look quite difficult to find or interface with. So I thought of doing it with a pressure sensor:

P = rho * g * h

I can measure P, g is a constant and h I'll get onto later. I can solve this for rho, and get the spesific gravity right?

The two sensors I've scoped out are:
http://search.digikey.com/scripts/DkSea ... X4250AP-ND
For an absoloute.

and
http://search.digikey.com/scripts/DkSea ... X2010DP-ND
for a differential

However I don't think these are submersable, even if they were I would like to avoid the hastle of having to sterilise them.

What I would rather do is stick a rubber hose over the nosle and then stick that into the tank, like so:

Will that work? Will the reading I get of air pressure in the tube be related to the spesific gravity? Will I need to keep the actual sensor above the tank?

If my pressure sensor measures the airpressure relative to 1 atmosphere, what does my value for h need to be? My height above sea level?

My other option is to use a differental pressure sensor, and have one probe in the air

In that case, what is my value for h?

does it make sense to measure a difference in pressure between two depths in the tank?

The value for h being the difference between them?



Sorry for the large number of questions. Any help would be appreciated.

Cheers,
James

 

[Muddydisco]

One very large flault with your plans!!!!
Co2!!!
The fermenting beer gives off co2 hence your pipes will fill with co2 and give inacurate readings

 

[unclepumble]

Would the production of CO2 by the yeast not screw up the readings taken by the sensors and therefore make calculation pretty impossible, , if you had a sensor attached to a submersed hose you would see the air space above the wort it was submersed in increase in pressure over the course of the brew.

I work at one of the biggest brewerys in the UK, and we still take regular samples and plot a graph of the fermentation process, as I think this is the only really accurate way to do it.

Bar reading regular samples on a spectrometer.

UP

 

[Aleman]

Would it not be easier to use the weight of the container and fermenting brew :hmm: ?

After all that is what Specific Gravity is (Sort of) The difference between the weight of a volume of wort and the same volume of water.

 

[robbo18]

you can buy electronic hydrometers, but they are expensive i think there is also a electronic u-tube meters that also do the same thing. they are expensive because they are used in industry not just for small projects. a dip pipe can also measure the pressure but you would need some compressed air and no doubt this would affect the brew.

 

[rabbie]

In industry it's common to have a stand pipe connected up to vessels with a sight glass, mainly to measure the level.
You could try and rig one up on the side of your FV (need to make it air tight :hmm: ), pop a hydrometer in and watch it drop over the course of the fermentation. If you want an electronic signal you'd need a sensor to measure the relative difference between top of the hydrometer and the liquid level, but that would need to take account of the yeast head probably. Difficult but it can be done.