data-raw/hydrometers/hydrometer-dims-README.md

In evanmascitti/asi468: Store Glassware Data and Other Information for Repeteated Lab Tasks

The dimensions are abbreviated using the symbols in ASTM D7928-17.

Each entry in the spreadsheet corresponds to a measurment made on the hydrometer.

Measurements abbreviations are followed by an underscore and then the unit in which they were recorded. It is more convenient to record the length units in mm as this is what a digital caliper usually reports.

The R script that builds the data object converts all the mm measurements to cm.

For the bulb volume, the entered value represents the average of 3 or more measurements.

The column pure_water_offset represents the hydrometer reading when placed in pure water at 20 deg C. If the value is positive, it should later be subtracted from the actual reading and also from the blank correction, because the reading should be zero in this pure-water condition.

EDIT: after trying this out, it made almost zero difference. I worked through the math by hand and I guess it basically doesn't matter, because this is already accounted for in the blank correction measurement, which is also "equally wrong". It very marginally affects the effective depth, but it's so little that it's not worth doing the extra correction. I am going to take the pure_water_offset column out of the csv file the column there and also remove the code insid soiltestr that uses this adjustment. Should I ever need to see how this was done, see soiltestr commit dda1338, file R/compute_hydrometer_fines_pct_passing` lines 49 and 56-94; it is explained pretty well there.

evanmascitti/asi468 documentation built on Dec. 4, 2022, 11:09 a.m.