samuls, I think we need a bit more info on your question. I'm a bit lost but here's what I think you might have meant...
What I think you might have been asking is, "For every centimetre of depth in a 50 litre keg, how much water am I adding?"
If that is the question, then it's an impossible one to answer but there are ways around this. Lucky I have had an IPA as I am actually going to think this through
The first thing to realise is that for any flat-bottomed, straight-sided vessel, the depth of the liquid can be easily determined and therefore, the volume can also be easily determined. I'm going to assume that everyone understands this.
The problem with kegs is two-fold...
1. Measuring the internal diameter accurately.
There are many ways to do this and we can come back to those if needs be. For now, let's concentrate on the real
2. The Dead Space
Okay, a normal keg is either convex or concave at the bottom (doesn't really matter which) and the rest of the keg is usually straight-sided. So we have one of the following... The grey area represents dead space.
Assuming that the rest of your keg is straight-sided as most kegs, except the old style, are, then all we have to worry about is the dead space.
Let's say your dead space is 5 litres...
With the keg on the left, things will be easy as you can measure your depth in the centre and then just add 5 litres.
The keg on the right will be not much harder. Just measure your depth, subtract the cms between the bottom of the 'dead space' and then add 5 litres.
I'd like to thank you for your question samuls but I'll get in trouble as I'm sure the guys working on the new calculator (the BIABacus) will now be trying to work out how to incorporate this.
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