How accurate is your volume?

[Black Devil Dog]

I recently bought a 40 litre Crown urn to begin BIAB brewing. The way I worked out how much liquid I needed was pretty simple, I got a 10 litre bucket, filled it to the 10 litre mark, tipped the water into the urn, did it again for 20 litres, same again for 30 and used a jug to add my 1 litre amounts. Marking the sight gauge with each addition.

After a couple of brews I thought I'd check my measurements against another bucket........ well they were different.

So which one is right?

I could have used another bucket for a best of three, but I decided to use my pretty unreliable mathematical skills to work out the volumes and see if I could prove one or the other correct.

The result, my workings were pretty close to one of them, but not exact and human error may have played some part in the result. Nevertheless I have opted to go with my own workings.

The other was out by some way and would have resulted in about 2 litres extra overall.

 

[verysupple]

I'm assuming your "unreliable mathematical skills" method was to measure the inner diameter of the urn and use V = pi x r^2 x h in which case as long as you measured the diameter accurately that's your best bet. Buckets aren't exactly scientific grade equipment so who knows what volume they really were.

 

[Bizier]

I know that on my kettle via cylinder volume 44mm is 10L, and if boiling you need to factor in the 4% expansion, so either multiply or divide by .96

 

[Bada Bing Brewery]

Weigh your water. 1 lt = 1 kg, then mark it.
Nearly gone
BBB

 

[WarmBeer]

Weigh your water. 1 lt = 1 kg, then mark it.
Nearly gone
BBB

Under the assumption you are on the planet earth, at or near sea level.

You know what happens when you assume...

 

[Yob]

You get stitched up by a ladyboy at the full moon party?

 

[Midnight Brew]

If you search for BIAB Equipment Calculator it should come up with the original copy but witht hat you plug in your numbers and diamater of the kettle and it works it out for you. Then just buy one of those old school 600mm stainless steel rulers and you'll be fairly accurate from then on. That calculator applies to round kettles. Cant remember who made it but I always run my beersmith figures through it just incase. Keep 2 copies of it, one original and one you edit and base your system off.

 

[JDW81]

My volumes are accurate enough for home brewing.

My volumes weren't exactly measured with scientific grade equipment (I don't think the old fire king 1L jug would cut it in a lab), but I hit my mash temps, and pre boil volumes so I'm happy.

JD.

 

[hellbent]

I use a 2ltr milk container to check my water 10ltr bucket.... just take notice when next in the supermarket to where they are filled with milk then use that as a guide. Don't do as I did once and trust a 3ltr plastic jug bought from a $2 shop, it turned out to be a fair whack under 3 litres!

 

[mosto]

Slightly off topic, but I had a similar realisation last night. I started my brewing journey a couple of years ago with a Coopers fermenter. A mates dad then gave me a second Brewcraft fermenter he didn't use anymore. This fermenter had markings by the manufacturer at 5, 10, 15, 20, 25 and 30 litres. The bloke I got it from had marked the 23 litre mark with permanent marker. I fermented 23 litre batched in this for a while with no problems, hitting expected OG most of the time.

I then began kegging and bought two 20 litre jerry's from bunnings, as I scaled back to 20 litre batches, but fermenting two at at time. Not easy to pour a can of goo through the small openings, so I took to mixing the batches up in the BrewCraft femermenter, to 20 litres, then transferring to the jerry. It came up to a point on the jerry where the moulding changed, so was easy to remember. I only did a couple more kits, then moved to extract, doing 10 litre boils, siphoning into the jerry and topping up to the point on the jerry that I remembered. I've been missing OG's fairly consistantly with since then and put it down to soething I was doing wrong since moving to extracts.

I needed a quick keg filler before trying my first BIAB, and only had about 800g of extract and 200g of grain leftover. I bought a Coopers Real Ale can from Woolies and chucked together a kits and bits English Pale Ale. I mixed it up in the BrewCraft fermenter (to the 20 litre mark), confident in all measurements and processes. The OG I took before transfer to the jerry was 5 points over, which seemed a lot. On closer inspection of the jerry, there is a 20 litre mark I hadn't noticed before which is an inch or so above where the fermenter had filled to. It appears there's a significant difference at the 210 litre between the two.

Out of curiosity, I checked my other jerry, that was sitting full of napisan, and it also had a 20 litre mark, although at a level to the other jerry. Both jerry's were bought from Bunnings and both look identical, except for the 20 litre mark!

I hadn't actually thoguht of weighing them with water in them. That maybe the may to check.

 

[verysupple]

Weigh your water. 1 lt = 1 kg, then mark it.
Nearly gone
BBB

Under the assumption you are on the planet earth, at or near sea level.

You know what happens when you assume...

And assuming that it's pure water at ~4 degrees C and that your scales are accurate...and the list of assumptions goes on .

 

[Midnight Brew]

The BIAB calculator I was talking about can be found here. Had toruble trying to attach it but here's the link

http://www.biabrewer.info/viewtopic.php?f=25&t=189

 

[GalBrew]

Or you could go and buy a more accurate measuring device. All mesauring equipment has tolerances. If you are super picky go and get the biggest laboratory style measuring cylinder (not beaker or flask) you can get your hands on. That will be the most precise thing.

 

[Ducatiboy stu]

Dont forget the meniscus.........

 

[Black Devil Dog]

As verysupple noted, there is really only one way to be 100% certain.

V = pi x r^2 x h

 

[Rocker1986]

I also use a 40L Crown urn for BIAB. What I did was to measure out the strike water for a batch one day by each litre using a measuring jug and then put markings on the sight tube at 25, 30, then each litre up to 35 or 36. It isn't 100% accurate by any means but it's close enough for rock n' roll. I generally hit my gravity targets and volumes so that's good enough for me.

 

[GalBrew]

Dont forget the meniscus.........

True that.

 

[WarmBeer]

As verysupple noted, there is really only one way to be 100% certain.

V = pi x r^2 x h

At ~20 degrees C.

Volume will increase up to 4% as you tend toward 100 degrees.

F&*king physics, man, how do they work?

 

[BobtheBrewer]

I recently bought a 40 litre Crown urn to begin BIAB brewing. The way I worked out how much liquid I needed was pretty simple, I got a 10 litre bucket, filled it to the 10 litre mark, tipped the water into the urn, did it again for 20 litres, same again for 30 and used a jug to add my 1 litre amounts. Marking the sight gauge with each addition.

If you have a concealed element in your 40L Crown Urn then here are the measurements you need. Use a 600mm steel rule.
Diameter is 33.7cm
The first 6 litres measure 78mm (to cover the element hump)
Thereafter 1 litre = 11mm
I use Brewmate as a calculator to work out how much water you need for a particular recipe, and to work out how much water you need for say 34.54litres
34.54 minus 6, multiplied by 11, plus 78 (=~392mm)
To work out your volume in the urn, using the measurement from the rule,
mm minus 78, divided by 11, plus 6
This is a pretty accurate measure, but remember that at various temperatures the volume will increase/decrease. I measure the volume before boil after mashout, and the volume after boil just before whirlpool.
I hope this is of some help.

 

[yum beer]

Use a standards approved measuring device, Pyrex measuring jug as an example.
And always assume that your assumptions are incorrect.