The problem with using the glass burette in our application is that to avoid false readings caused by seepage past the piston ring we have to use a thickish oil. This means that in order to get a truly accurate reading, it would be necessary, after filling to the top of the plug hole, to wait hours until all the oil clinging to the side of the burette had drained down. This is not practical, hence the specified measuring technique involving taking the reading within 30 secs. It the remaining oil clinging to the side that is the reason for the different reading given by the digital burette. However, the this amount will vary according to temperature and the exact time with that 30sec period, which is why Tal-Ko's 0.4cc difference may in some circumstances not be the correct allowance, and that is when the problems start.
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