Instrument Calibration Intervals: Self-Calibration Accepted?

[likephysics]

Just out of curiosity why is the calibration interval 1yr for lab instruments like DMM, scope etc.
Why not 2 years.

Also, you use a higher accuracy bench DMM to calibrate a hand held DMM.

Instead of getting calibration done by an outside agency, Why not calibrate the handheld DMM yourself using an already calibrated bench DMM.
I am trying to ask if "self-calibration" is accepted in the industry.

 

[Bobbywhy]

likephysics,

Get used to calibration of laboratory instruments and the reasons why we do it by going to the standards folks at:

http://www.nist.gov/calibrations/upload/sp250-46-2.pdf

Be sure to check Section 5.

Cheers, Bobbywhy

 

[davenn]

Calibration is normally done using very high precision signal, voltage , current sources etc ( depending on the instrument being calibrated.
This is why it generally costs lots of money to get signal generators, spectrum analysers, oscilloscopes etc calibrated by a certified calibration lab.

I guess a 1 yr period was chosen as a tradeoff between calibrating too often and not enough
Components can age a lot in 12 months time and cause the calibration to become very poor
and as the instrument gets older the components will likely to age even faster

Instead of getting calibration done by an outside agency, Why not calibrate the handheld DMM yourself using an already calibrated bench DMM.
I am trying to ask if "self-calibration" is accepted in the industry.

generally ... no it wouldn't, very few labs would have the precision test equip as I mentioned above. Any business that owns instruments that need regular calibrating will be required to show proof of an independently done calibration certificate

I'm a certified Trimble service technician and the company I work for I do calibration certificates on optical surveying equip. for our customers. Those customers can be required to produce a cal cert to a project manager that they may be contracting to.

Dave

 

[sophiecentaur]

Just out of curiosity why is the calibration interval 1yr for lab instruments like DMM, scope etc.
Why not 2 years.

Also, you use a higher accuracy bench DMM to calibrate a hand held DMM.

Instead of getting calibration done by an outside agency, Why not calibrate the handheld DMM yourself using an already calibrated bench DMM.
I am trying to ask if "self-calibration" is accepted in the industry.

It depends upon what 'the industry' needs, for a particular application. It has to depend on the particular circumstances. Sometimes, it is quite sufficient to check that results from two locally available instruments agree to within the particular required limits. You wouldn't often need to check the Mains Volts to 0.1% accuracy, for instance.

 

[dlgoff]

Equipment calibration is a huge issue when it comes to the Food & Drug Administration.

http://www.fda.gov/ScienceResearch/FieldScience/LaboratoryManual/ucm171880.htm

This procedure specifies the schedule and requirements for maintenance, performance, calibration, and verification of laboratory testing equipment. Meeting the criteria in this procedure demonstrates control of the maintenance and calibration parameters needed to achieve the accuracy of instruments used for analytical testing.

http://www.fda.gov/ScienceResearch/FieldScience/ucm171821.htm

The program for calibration of equipment demands that calibrations and measurements made by the laboratory are traceable to the International System of Units.

 

[TurtleMeister]

It depends upon what 'the industry' needs, for a particular application. It has to depend on the particular circumstances. Sometimes, it is quite sufficient to check that results from two locally available instruments agree to within the particular required limits. You wouldn't often need to check the Mains Volts to 0.1% accuracy, for instance.

Yes.

I was the calibration technician for a manufacturing facility a few decades ago. I did calibrations for electrical test instruments including voltmeters, wattmeters, power analyzers and many more. We had what we called the "in house standards", which were only used for calibrating the other instruments. The "in house standards" were generally of higher stability and accuracy than the normally used instruments. They "the in house standards" were calibrated once every six months by an outside agency. Or it may have been once a year for some instruments. My memory fails me. A calibration certificate was also issued by the outside agency for proof of traceability for each "in house standard". The frequency of calibration for the instruments used in manufacturing varied, but most of them were every month. A log was maintained for each manufacturing instrument and a sticker was placed on it after it was checked.

However, like sophiecentaur said, all of this may vary depending on the industry. The most important thing, and the thing that most all industries will have in common, is the traceability requirement.