How do you measure your boiler volume

[lord groan]

I can work out volumes fine, thats not the question, I have a Parry tea urn, its label states 27l, but the "max" marker embossed on the side is about 8cm below the rim, the dimensions are 32cm deep by 40cm diameter. So
40cm/2=20 =the radius.
Area of base is therefore pi x r2= 3.142 * 400= 1256.64cm2
This means for every cm deep I have 1.256litres, so my 27l boiler actually holds 40.2litres. Parry obviously take the safe useable volume as the figure, rather than the actual tub capacity. I reckon 40l should be fine to use as a boiler but that raised my real question which is
many of you good people use a buffalo 40l or Apollo 40l boiler. Is that the actual capacity or the safe usable capacity?

[AnthonyUK]

The Buffalo 40l is actually 50l but the usable limit is where the handles screw on which could leak if not sealed.

[Linus]

According to the software on the BIABrewer site a 40 litre buffalo its 8.7mm(0.87cm) is 1 litre.

[Cazamodo]

I have a sight glass now.

I used to use a stick.

[TC2642]

by sight, I know roughly where I want the final volume to be in the boiler and aim for that.

[Fil]

SS Ruler dipstick. in my 98l ss stock pot 1 cm is just about 2L

and for liquor into the tun i am gonna use scales to weigh the volume,

[hebbstar]

I use a copper dipstick with marks on it for a 70 litre pot.

3 cm = 5 litre.

Makes the maths interesting when stressed !

Cheers

[Jim]

Tape rule as a dipstip. My boiler is cylindrical, just over 33cm tall and full capacity is 33l, so volume of liquid in litres is (near as makes no odds)

33 - measurement.

[Frothy]

Of course when the liquid is boiling it will take up a larger volume than when it's cold.
I made the mistake and calibrated my sight glass with cold water - there is quite a big difference!

[Fil]

mass adjusted to consider gravity ie if 1040 1.04kg per litre.. should be a good indicator (i hope:) )

[Cazamodo]

I've always took a reading at boiling and multiplied by .96. I have no idea if thats correct haha.

[Fil]

I've always took a reading at boiling and multiplied by .96. I have no idea if thats correct haha.

me neither, tho im currently running under the assumption mass is temperature independent??
based on nothing other than recall of a long ago lesson at school.
tho the temperature may effect the measuring device.. So my intention is to sit upon an insulation sheet.. and monitor the ambient temp under the scales when testing the set up.
im still collecting the bits atm.

The mass of the tun contents may change however as the grist absorbs the liquid as some gasses in the air may also get involved.. making cus-cus on the scales would puzzle me as mixing 100g of pasta with 160g of boiling water resulted in a mass greater than 260g???
this was explained to me in the pub.. so b*llsh*t warning, that the air is also filling some of the volume of the expanded pasta when hydrating??? tho it could also be error creeping into the electronic scales as the heat from the water takes effect on the electronics???

[mooj]

I measure the head space and subtract from the full volume. I have a 70L bergland pot and 1" is near enough 4L.

[Maltmaniac]

Beer engine from Mr Wheelers site has a very nice vessel gauging app on it which I find accurate using a ruler/tape measure. Usually my measurements for mash and sparge volumes are spot on when using it. It's simple and friendly to use, check it out.

[phil.dadd]

I calibrated my pot by reading the depth of 20kg of water from 7° to 95°. I determined a depth per litre at various temperatures to use. The difference wasn't as much as I thought tbh - the depth was 21.5cm at 7° and only 22cm at 95... About 2.5% difference then... I didn't account for steam extraction as I raised the temperature, but I kept the lid on to keep that to a minimum, and not much steam was produced to be honest as it didn't boil...