Calculated Vol. v. Measured Vol. - Help Please

[MEPNew2Brew]

For reasons relating to equipment limitations, I don't have a reliable way to measure post-boil volumes accurately. I am confident in my pre-boil measurement as well as my gravity readings.

Rather than actually measuring post-boil volume, would it be reliable to just calculate it using the pre-boil volume and gravity, and total gravity points, and the post-boil volume and total gravity points? Total gravity points shouldn't change between pre-boil and post-boil, right?

For example -

Pre-boil - 7.74 gallons * 1.052 (SG) = 402.48 gravity points

Post-boil - X gallons * 1.061 (OG) = 402.48 gravity points

Solve for X

X gallons = 402.48/61

X = 6.6

Sound right?

Thank you for the assistance. I am going a bit crazy with trying to get my process to be more consistent. A big issue I have is an inability to measure post-boil volumes correctly.

 

[turkeygecko]

Looks right to me, but I'm not certain.

You could just mark a dowel with volume notches, sanitize, and dip in post boil wort to measure. They cost like $3.


Sent from my iPad using Home Brew

 

[acidrain]

There is no reason NOT to measure your volumes... it's just part of brewing.
Equipment limitations is bull. Like Turkeygecko said, mark your stir spoon or a dowel. If want consistency, measure your volumes.

 

[Oginme]

You can measure post boil by the amount transferred to the fermentor plus the amount of material left in the kettle. I use this as a double check (using the calculations you cited above) on my previous measurements of pre-boil volume.

 

[MEPNew2Brew]

Thanks for the input folks. I use a wood dowel to measure pre-boil. I am hesitant to use it post boil because I am concerned that StarSan will not sanitize it.

Do you use a wooden dowel to measure post boil?

 

[Grannyknot]

Dowels and volume sticks never worked well for me.
Mark your fermenter at 4-5-6 gallons with a sharpie (Or if you use brew buckets, they should be pre-marked).
Then, what ever you don't drain into your fermenter (kettle losses) can be dumped into a brew bucket for easy measuring.
Your post boil volume is whatever is in your fermenter + the kettle losses.

I collect all my mash tun runnings in a brew bucket so that I can measure pre-boil volume as well.

Proper volume measurements is key to good brewing.

 

[LandoLincoln]

Thanks for the input folks. I use a wood dowel to measure pre-boil. I am hesitant to use it post boil because I am concerned that StarSan will not sanitize it.

Do you use a wooden dowel to measure post boil?

They sell aluminum yard sticks.

 

[hio3791]

They sell aluminum yard sticks.

This is what I use. It's easy and accurate. I use Brewzor which easily calculates volume from measured height and compensates for heat expansion. The math itself isn't difficult if you rather use a spreadsheet.

 

[Happywanderer]

Aluminum yard stick at Home Depot is $2.99.

Dump a gallon of water in your pot. Measure.

Dump another gallon of water in your pot. Measure.

Rinse and repeat until your pot is full.

Make sharpie marking at 5.5 gal mark +4% ... 4% is the rough estimate for expansion of wort from 68* to 212* (room temp to boiling).

For my pot it is exactly 8 inches. I like round numbers.

Measure your wort at several points - preboil, every 20 mins during boil, and at flame out.

This is not science lab accuracy - but it will be close enough. And I go with 5.5 gallons because crap in the bottom of the brew kettle will likely mean you lose about .25-.5 gallon. So you should end up with just over 5 gallons in the fermenter.

 

[jkcolo]

If you are afraid of the wooden dowell touching the wort, you can calibrate your measuring stick doing the opposite: measure from the top of the pot down to the surface of the wort without touching the wort itself. Voila, you have your accurate post-boil volume.

 

[MEPNew2Brew]

If you are afraid of the wooden dowell touching the wort, you can calibrate your measuring stick doing the opposite: measure from the top of the pot down to the surface of the wort without touching the wort itself. Voila, you have your accurate post-boil volume.

Now, measuring from the top down is something I did not think of.

Off to HD or Lowes for an aluminum yard stick.

 

[wilserbrewer]

I would have no issue measuring the hot wort at flame out with a (non sanitary) wooden dowel. FWIW


Wilserbrewer
Http://biabbags.webs.com/

 

[wilserbrewer]

I would have no issue measuring the hot wort at flame out with reasonably clean (non sanitary) wooden dowel. FWIW


Wilserbrewer
Http://biabbags.webs.com/

Wilserbrewer
Http://biabbags.webs.com/

 

[DurtyChemist]

I use a tape measure then calculate the volume of a cylinder. 3.14*7.5*7.5*0.004 (cu in to gallons) = gallons of wort pre boil. No need to purchase anything.

 

[thekraken]

I collect all my mash tun runnings in a brew bucket so that I can measure pre-boil volume as well.

I did this as well, but then it occured to me that my plastic brew bucket might not like the 150 F wart and leach nasties into my brew, so I stopped doing that and started collecting runnings into SS stock pots. I never followed up on this notion, so is it food safe?

 

[barleywhore69]

I stick my spoon down to the bottom, mark the water level with my thumb on the spoon, then hold the spoon up to the depth chart I made. I made the chart by pouring in a gallon, making the mark on the chart, pouring in another gallon, mark the chart. I also put the markings for two different kettles that I use on the same chart for convenience.

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[thekraken]

Also, OP, you could etch your pot: https://www.homebrewtalk.com/f257/how-add-permanent-volume-markings-kettle-illustrated-463099/

 

[helibrewer]

For reasons relating to equipment limitations, I don't have a reliable way to measure post-boil volumes accurately. I am confident in my pre-boil measurement as well as my gravity readings.

Rather than actually measuring post-boil volume, would it be reliable to just calculate it using the pre-boil volume and gravity, and total gravity points, and the post-boil volume and total gravity points? Total gravity points shouldn't change between pre-boil and post-boil, right?

For example -

Pre-boil - 7.74 gallons * 1.052 (SG) = 402.48 gravity points

Post-boil - X gallons * 1.061 (OG) = 402.48 gravity points

Solve for X

X gallons = 402.48/61

X = 6.6

Sound right?

Thank you for the assistance. I am going a bit crazy with trying to get my process to be more consistent. A big issue I have is an inability to measure post-boil volumes correctly.

Before I had a sight glass I used a marked dowel and 2 silicon O-rings, one set at Pre-boil volume, the other set at post-boil volume, that way I wasn't trying to read values through the steam bath.

 

[kanzimonson]

I do exactly what you're proposing in the original post. I know where my pre-boil line is in my kettle, I check the gravity, make adjustments if it's off, and then start boiling. Then I know when it gets to X gravity then it's also at the right volume.