Calibration does not involve adjustment. In fact adjustment is ill advised as it invalidates all previous calibration history and breaks the trends. Calibration defined as only comparison to known reference with known uncertainty, no adjustment. Adjustments are service procedure which can be performed between two calibrations to get "before'' and 'after' conditions. Labs that do adjustment without customer consent have good chance to make things worse , if we talking about precision instruments. Equivalent in metrology would be trying to adjust national 1kg standards to IPK every time when those are sent in for comparison. That would add lot of unwanted uncertainty. In metrology drift itself is not much of a problem, problem is to have it drift in predictable , ideally linear matter, so corrections can be applied by math at the time of use.
On June 6, 2020 11:58:55 AM EDT, Miguel Yepes <[email protected]> wrote: >But in calibration you have to make some type of corrections and on >verification you dont you just compare to be within the manufacturer >ranges. Now for instance Tektronix has verification manuals to check >their equipment, before they called them calibration manuals and >included adjustment to meet the specifications of the manufacturer. Now >the user cant adjust easily because most are via software and is not >commercially available. > >________________________________ >From: volt-nuts <[email protected]> on behalf of Dr. >David Kirkby <[email protected]> >Sent: Saturday, June 6, 2020 9:19 AM >To: Discussion of precise voltage measurement ><[email protected]> >Subject: Re: [volt-nuts] What if “verification” in metrology? > >On Sat, 6 Jun 2020 at 12:18, Florian Teply <[email protected]> wrote: > >> Funny thing how things work out time-wise: I had a discussion >yesterday >> on the very topic during re-audit for ISO 9001. >> > >Yes, it is. > >In basic terms, verification in metrology is a very slimmed down >> calibration: For a calibration, you essentially check every range of >> your instrument at usually five or more spots within that range in >> order to determine accurracy of your instrument in each range. >> For a verification, you do this only at the spot where you intend to >> measure. So if you were to measure a nominal 7.2V source, you'd >compare >> the reading of your meter with your, say, known good 7.5V reference >> instead of doing a full calibration of the meter. >> > > >> So, in order to determine whether or not your chinese voltage >reference >> meets its specs, you'd check your meter against, say, the >> well-characterized LTZ1000A you happen to have in your lab. >> >> Strictly speaking, you still have to do it as carefully as you would >do >> a real calibration, taking all known effects into account, but it's >> still much less time-consuming than a full calibration as you check >only >> one single point instead of all possible ranges with five points >each. >> >> Does this help answer your questions or did I just bring up more >> questions than answers? >> > >Yes. I wish VIM was a bit more explicit about it. A single sentence >just >does not do it justice. > >best regards, >> Florian >> > >Dave >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com >and follow the instructions there. >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com >and follow the instructions there. BR, Illya Tsemenko _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.
