All-Grain Brewery w/Automation--Concept Phase

Sawdustguy said:

Pressure is a very accurate way to measure volume. The reason that temperature can affect the reading is as the air in the tube that goes to the pressure sensor gets warm the pressure in the tube increases. Here is a video using pressure sensors to measure volume.

http://www.youtube.com/watch?v=2VaRCh_TuFM

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Sure its accurate if you know the density of the liquid. But if its unknown? Or approximate? Like I said in an above post, you could easily be off by 3/4 of a gallon or more.

Sawdustguy said:

Pressure is a very accurate way to measure volume. The reason that temperature can affect the reading is as the air in the tube that goes to the pressure sensor gets warm the pressure in the tube increases. Here is a video using pressure sensors to measure volume.

Click to expand...

Firstly I'm at work so can not watch the video (damn iron curtain!) so I appologise if this is already answered in that;
Why is there air in the tube, shouldn't the liquid act on the pressure sensor?
I understand that if you were measuring a gas that temperature would be import but not so much for a liquid.

kerklein2 said:

Sure its accurate if you know the density of the liquid. But if its unknown? Or approximate? Like I said in an above post, you could easily be off by 3/4 of a gallon or more.

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Your only problem is with the mash tun. If you know how much strike water you put in from the sensor in the HLT and how much sparge water you are using from the HLT you are golden. All other volumes can be calculated if you know the dead space in the mash tun and boil kettle. This method has worked very well for alot of brewers. I have no idea why it couldn't work for you. If you want to spend alot more money for flow meters more power to you. Maybe your company will buy them for you. If your company will spring for the flow meters this whole conversation is moot.

mattd2 said:

Firstly I'm at work so can not watch the video (damn iron curtain!) so I appologise if this is already answered in that;
Why is there air in the tube, shouldn't the liquid act on the pressure sensor?
I understand that if you were measuring a gas that temperature would be import but not so much for a liquid.

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Because you are actually measureing how much the air in the tube is being compressed by the volume of water. Temperature affects your reading because temperature has a direct effect on air pressure. This inaccuracy due to temperature can be overcome with a bubbler system. It still is a very inexpensive way of measureing volume because the pressure sensors are on about $6.00 each and the aquarium pump for the bubbler is $10.00. It works great for those of us who can not justify purchasing a couple $250 flow meters or level sensors that work at these elevated temperatures. There are less expensive flow meters and level sensors but they don't function at temperatures up to 175*. CodeRage is done some work on the bubbler system and it seems to work well. Here is Jason's (CodeRage) excellent explaination.

Using static air the heat will cause the air to expand and push out the bottom, which is okay, the readings will be accurate because it is venting. The problem is when cooling the volume of air has changed and thus creates a relative vacuum in the tube. A bubbler doesn't have this problem because it is constantly venting the pressure.

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Sawdustguy said:

Your only problem is with the mash tun. If you know how much strike water you put in from the sensor in the HLT and how much sparge water you are using from the HLT you are golden. All other volumes can be calculated if you know the dead space in the mash tun and boil kettle. This method has worked very well for alot of brewers. I have no idea why it couldn't work for you. If you want to spend alot more money for flow meters more power to you. Maybe your company will buy them for you. If your company will spring for the flow meters this whole conversation is moot.

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I get it now. Put the pressure sensor in the HLT and you are just calculating how much water you move in and out of there. I was imagining the pressure sensor in the MLT where you'd never get good accuracy.

kerklein2 said:

I get it now. Put the pressure sensor in the HLT and you are just calculating how much water you move in and out of there. I was imagining the pressure sensor in the MLT where you'd never get good accuracy.

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Yes, you are right on the money!!

The trick with a MLT pressure sensor is not to try for a volume measurement, just use it to maintain level during sparge water feed and transfer of wort to BK. The formulas for gravity correction when adding malt and the SG change as conversion progresses would be a bit of a challenge to work out and implement.

kladue said:

The trick with a MLT pressure sensor is not to try for a volume measurement, just use it to maintain level during sparge water feed and transfer of wort to BK. The formulas for gravity correction when adding malt and the SG change as conversion progresses would be a bit of a challenge to work out and implement.

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But the gravity of the wort will be changing during a runoff and sparge.

The goal was to maintain water over top of grain bed while introducing sparge water, significant changes in SG would happen after sparge water was expended. Float switches with adjustable switching elevation would be simpler to implement, but if you can obtain analog hardware, why not.

kerklein2 said:

But the gravity of the wort will be changing during a runoff and sparge.

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What Kevin (Kladue) is describing is simply Fly Sparging. You maintain a 2" layer of liquid above the grain bed while draining the Mash Liquor Tank from below the false bottom or through a manifold or braid. When you have the desired amount of wort, you are done. I am all for simplicity, so I use a Blichmann Autosparge, which is exactly what Kevin described as a float. I recieved it as a gift, but it is only $50.00 and if someone has the imputus, it can be DIY'ed much less expensively.

Sawdustguy said:

I am all for simplicity, so I use a Blichmann Autosparge, which is exactly what Kevin described as a float. I recieved it as a gift, but it is only $50.00 and if someone has the imputus, it can be DIY'ed much less expensively.

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In what I've read, you've received 2 March 809s and the Blichmann Autosparge as gifts... You're starting to make me realize my friends suck.

diatonic said:

In what I've read, you've received 2 March 809s and the Blichmann Autosparge as gifts... You're starting to make me realize my friends suck.

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The two pumps were given to me by two different people (my wife gave me one and a good friend friend gave me one) as birthday gifts at a birthday party given for me when I turned 50 (it was my first birthday party ever) and the Autosparge was a Christmas gift this year. Lucky I guess.

Sawdustguy said:

The two pumps were given to me by two different people (my wife gave me one and a good friend friend gave me one) as birthday gifts at a birthday party given for me when I turned 50 (it was my first birthday party ever) and the Autosparge was a Christmas gift this year. Lucky I guess.

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Lucky is right. All I've ever got is some AHS gift certificates and a beer mug that I've never use.

Sawdustguy said:

The two pumps were given to me by two different people (my wife gave me one and a good friend friend gave me one) as birthday gifts at a birthday party given for me when I turned 50 (it was my first birthday party ever) and the Autosparge was a Christmas gift this year. Lucky I guess.

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Old Fart! Haha you made it this far might as well be on the survival mode of life now. Congrats 50's nothing the clock speeds up as we get older. Only as old as you think, i'm still thinking 12 ask the wife. LOL!