How to calibrate an analytical balance

[pippo]

People,

 

I have Class S NIST weights, but I dont understand what is meant by "tolerance" when calibrating a Mettler. Say, I grab a 100g weight, zero the scale, place it on the pan, and get a weight - say 99.9965g. That is pretty good to me, but when a manual says "calibrate to NIST tolerance for class s ", what do they mean? Sjhouldnt that imply a min /max tolerance? Where then do you find this tolerance?

 

Thanks

[CharonY]

If you use certified weights the only thing you generally have to do is to go into the calibration mode, put the weight on it and then just type in the value. If you want to know whether your measurements are within allowed tolerances there are generally reference handbook from NIST (i.e. for overall guideline) or from the manufacturer.

[John Cuthber]

People,

 

I have Class S NIST weights, but I dont understand what is meant by "tolerance" when calibrating a Mettler. Say, I grab a 100g weight, zero the scale, place it on the pan, and get a weight - say 99.9965g. That is pretty good to me, but when a manual says "calibrate to NIST tolerance for class s ", what do they mean? Sjhouldnt that imply a min /max tolerance? Where then do you find this tolerance?

 

Thanks

 

http://www.nist.gov/calibrations/upload/78-1476.pdf

 

Page 11 gives the tolerances for class S

 

But I have the feeling that that system may have been overtaken by newer standards .

[pippo]

Big thanks, Char and John. That link was useful. (Char, that mettler is from the 1950's. Mechanical. No "cal" mode on those) Balance still works. Its a real piece. Like a swiss watch.