Demijohn volume scale

Postby Cerberus » Sun Apr 20, 2014 18:10

Demijohns are usally described as 4.5 litres, but are they really and where exactly is the 4.5 litre mark? With the help of a measuring cylinder I marked out a Muntons demijohn (also sold by Wilkinsons under the Wilko label) litre by litre to produce this reference scale which may help you when trying to add specific quantities of ingredients or make the volume up to a specific amount. The base of the dj says "450cl", but as you can see the demijohn is actually 4.6 litres if filled to the neck ridge. (To the absolute brim it's 4.65 litres). I think these demijohns were really designed to be 1 imperial gallon (=4.546 litres) which you can see falls at the base of the neck.

The second attached image is a tidied up copy of the scale that you can print out (at 150dpi — a mm scale is included so you can check you've printed it out life size) and tape it down the side of your demijohn as in the first picture. Note that the scale should be read from the side: the thickness of the glass and refraction causes the level in the shoulder region to seem somewhat higher when viewed from above. The printable scale has extra markings (the "V"s) which show where the liquid level will seem to be when viewing the scale vertically instead of side-on.
demijohn-s.jpg
demijohn with litre scale
demijohn-s.jpg (58.28 KiB) Viewed 2555 times


Note that although demijohns seem to be a standard product it's possible that other brands of demijohn may differ size. For reference, the Muntons one is 56cm in circumference and in height it's 265 mm to the base of the neck ridge.
Attachments
demijohn-scale.jpg
demijohn scale for printing out
demijohn-scale.jpg (64.53 KiB) Viewed 2555 times

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Re: Demijohn volume scale

Postby Moley » Sun Apr 20, 2014 18:18

The trouble is that even if you've got several DJs which appear to have come from the same manufacturer, they could still vary slightly.

I have calibrated a few of my DJs and they range from 4.6 to 4.9 litres, averaging around 4.75 litres. This can be useful if you rack wines to a slightly smaller jar.
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Re: Demijohn volume scale

Postby Cerberus » Tue Apr 22, 2014 00:52

I didn't realise there was that amount of variation between djs. I would expect dj's of a given make would be very similar though since they're produced in moulds so should be pretty uniform, and my 3 Wilko/Muntons djs all seem to be identical. Maybe my scale will only be reliable for that make though.

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Re: Demijohn volume scale

Postby Moley » Tue Apr 22, 2014 06:38

I would agree, if your DJs have come from the same factory and modern batching techniques are putting exactly the same weight of glass into the moulds, then volumes should be consistent.

Most of my 30-40 DJs are 30-40 years old and have not all come from the same factory, I have at least 3 different profiles and their weights (and therefore wall thicknesses) do vary.
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Re: Demijohn volume scale

Postby Gorty » Fri Oct 24, 2014 01:08

Yup, got the same problem. almost as many profiles as 'DJs' But thanks anyway Cerberus.

Buy wisely, brew carefully, drink copiously and stuff the rest!

Fermenting:

25L The Range 'MYO' Red.
25L The Range 'MYO' White.
5L 'WOW' Pineapple.
5L 'WOW' Blueberry.
5L 'WOW' Pomegranate.
5L 'WOW' Mango.

Clearing:

25L The Range 'MYO' White.
25L The Range 'MYO' Red.
5L 'WOW' Orange 2nd attempt.
5L 'WOW' Ribena.

Bottled:

5L 'WOW' First attempt.
5L 'WOW' Cranberry.
5L 'WOW' Apple.
5L 'WOW' Pomegranate.

Drinking:

25L The Range 'MYO' white.
25L The Range 'MYO' Red.
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Re: Demijohn volume scale

Postby Frogfurlong » Fri Oct 24, 2014 11:23

1litre of water = 1kg*

weigh the container, leave on the scales and add 1kg of water at a time and mark the level, this will give you a reference for any size/shape of container.

Obviously you can make smaller units with smaller amounts 100g = 100ml etc :)

*based on pure water, but close enough for our purposes.

People assume that Brewing is a strict progression of cause to effect, but *actually* from a non-linear, non-subjective viewpoint - it's more like a big glass of wibbly wobbly... beery weery... stuff.
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Re: Demijohn volume scale

Postby Crastney » Fri Oct 24, 2014 13:02

each time you fill a DJ, put in 1 litre at a time, (maybe easier when washing or cleaning than when adding must or racking wine) and add markings in permanent marker to the outside, you'll soon find you've marked all your DJs.

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