I just purchased 2 inexpensive alcohol filled LIG(liquid-in-glass) thermometers for the pool. Sitting side by side 1 is consistently reading 3deg higher than the other and then I noticed both have a black horizontal line marked on the glass, one lining up about 70Fdeg(~21C) and one lining up about 67deg(~20C) on the plastic housing temp scales. So there's the reason for the 3deg diff in temp.
After some searching, I learned the black line is a reference temperature line put on thermometers when temp scale is printed on a separate housing and meant to align with a certain degree on the scale, but what is the correct 'reference' scale temp alignment value? I also came across something called an alcohol temperature correction chart that seems to show 20C deg as the baseline temp (0 correction needed).
For $10, I realize temp reading varying by 2-3deg is probably to be expected, but I was just curious if anyone here may know if the reference mark on an alcohol filled thermometer is supposed to be lined up with the 20degC mark on the plastic temp scale?
After some searching, I learned the black line is a reference temperature line put on thermometers when temp scale is printed on a separate housing and meant to align with a certain degree on the scale, but what is the correct 'reference' scale temp alignment value? I also came across something called an alcohol temperature correction chart that seems to show 20C deg as the baseline temp (0 correction needed).
For $10, I realize temp reading varying by 2-3deg is probably to be expected, but I was just curious if anyone here may know if the reference mark on an alcohol filled thermometer is supposed to be lined up with the 20degC mark on the plastic temp scale?
