Quality Calibration Procedures - Frequency of equipment calibration - ISO 17025

[eng.luma]

hello all
am a new member here and i really need a quick help, i recently get the job of a quality officer applying iso 17025, i really need a helping hand with my tasks;
while prapairing the quality procedure of calibration i couldnt find any information about the Frequency of equipment calibration so i would be graet full if any one get me some links to visit or some tabels that may help.
i also need a quality procedure for estimating uncertainty of measurments
thanks alot for any help

[JerryStem]

What kind of equipment do you have that needs calibrating? Something normal like gageblocks or thermometers, or something more obscure that isn't well documented?

I've found if you keep it reasonable & can prove it, you can set your own intervals. Start out at something common like 1 year, 6 months, whatever. Then over time if you can show that the items were "in-spec" each time, you can extend the intervals.

As for MU, good luck. We've had lots of problems thru A2LA but I think it may be resolved finally. If you get a good assessor, you have a much better chance the first time around.

Jerry

[eng.luma]

thanks a lot for your reply, am working to get the accreditation for a fertilizer and plant analysis laboratory so the equipments are: spectromotometers, ovens, thermometers, atomic absorbsion, Kjeldahl auto digestion and titration. for me i thought that one year could be suitable but i need to know if i may have some spesifications or a limited interval of time!!!!!!!

i will be glade if you could send me some web sights that give a free quality procedures i still need some help to get rid of estimating uncertainty of measurments to control the quality of our laboratories test result
thanks a lot for you sir

[JerryStem]

I'm not familiar w your equipment so I cant say for certain about intervals but 1 year would probably be a good starting point.

As for measurement uncert and procedures, start with A2LA's site. From there you may find more links. Use Google to look up Measurement Uncertainty & you'll be kept busy for awhile.

Good luck.

Jerry

http://www.a2la.org/

[Kevin H]

Another site to checkout is the United States National Institute of Standards & Technology usually know by the acronym NIST. They look to have some good information on measurement uncertainty at the following web address:

http:/physics.nist.gov/cuu/Uncertainty/index.html

[preetham]

To my understanding the calibration frequency will depend on the usage of the instruments.if you use the instrument very offenly then you have to calibration frequency should be of 6 months or min .if your usage of the instrument is very less then you can fix the frequency for one year or more.

Preetham

[Jim Wynne]

Originally Posted by preetham

To my understanding the calibration frequency will depend on the usage of the instruments.

Actually, after the initial interval has been set, the "as found" condition in subsequent calibrations should be used. If the as-found condition after x number of calibrations is continually such that adjustment isn't necessary, it may be reasonable to extend the interval.

[Baldrick]

In working out your frequency, the capability of your equipment is a major factor, as the other posters have said above. However, you should also consider what would happen in the event that an instrument was found to be "out of calibration" i.e. it needed an adjustment.

In this circumstance, you have to review ALL OF THE RESULTS MADE USING THAT EQUIPMENT SINCE THE LAST SUCCESSFUL CALIBRATION. This is because, in theory, the instrument may have gone "out of calibration" immediately, and all subsequent results may have been affected.

This is covered in ISO9001 clause 7.6 (capitalisation is mine):

"...the organisation shall assess and record the validity of the previous measuring results when the equipment is found not to conform to requirements. The organisation shall take appropriate action on the equipment, AND ANY PRODUCT AFFECTED".

So if you calibrate a critical instrument for the first time in 12 months and find that it has "shifted" and requires adjustment, you need to review all results from that instrument during the past year and determine whether you may have shipped any nonconforming product. This could be a headache, especially if your product is safety-critical.

So you may want to set your calibration frequencies at more regular intervals, even if you have confidence in your equipment.

FWIW, our lab has devices that are checked as frequently as every hour, with weekly and/or monthly checks also done in house using traceable transfer standards. Devices are also sent out annually to their (ISO17025 accredited) vendors for service, maintenance and calibration.