Calibration of Devices

Greetings all, for those who dont know my rescent posts i work for a small company to which i have been given control of all things BRC and food safety related. YAY   i say rescent its been a year now and although im finding my way i still get caught out by something new....

So..... V6 section 6.3 if i am interpretating this correct is that for example:

Scales and temperature probes that are used for monitoring CCP's or related to legality ie Weight of finished product must be calibrated to a recognised standard if one exists.

so my question would be, If my weights are calibrated  and my reference probe is calibrated to a UKAS or simular standard externally. is it acceptable to calibrate internaly based on risk from that? do i still need to send each probe /scale off to be individually calibrated to that same standard?

Also Moisture machines - we do not use them for any CCP or legal reasons we just do this as a point for quality. i presume there is no standard for this equipment because it uses temperature and weight which again can be done using the calibrated weights. and temperature is built in to the device. my interpretation would be as above for probes and scales. am i right there?

Lastly Aw machines this is used for final product analysis and is food safety related so i would argue it needs to be calibrated to a standard which is?) and where above id would use a calibrated weight or ref probe does such a thing exist for Aw machines???

Any help here appreciated, i feel the company is throwing money away if im right. which i could put towards buying some new scales and the like....

Kind Regards

Dave

Based in the UK

Hi

As long as you use an appropriately accurate and precise methodology for calibration, you need to simply maintain traceability back to the original national or international standard.  Whoever did the calibration of your existing primary equipment will have done the same. 

As an interesting point, I once had an auditor, one of those who inevitably knows everything and is always right, who gave me a non-conformance because my master thermometer, which had been calibrated by the National Physical Laboratory in the UK, had a stated offset of 0.2 Deg C.  His view was that an offset was unacceptable on a master thermometer!

Some NC's can be difficult to correct if dealing with crass stupidity.  Always be prepared to challenge an auditor when you know better.

Oh, the Aw question.

Your water activity machine should come with instructions as to how to calibrate.  I haven't used one for a while, but a decent reference book should give the Aw of various standard solutions, if that helps.

Regards,

Philip (UK)

 

Scales and temperature probes that are used for monitoring CCP's or related to legality ie Weight of finished product must be calibrated to a recognised standard if one exists.

 

so my question would be, If my weights are calibrated  and my reference probe is calibrated to a UKAS or simular standard externally. is it acceptable to calibrate internaly based on risk from that? do i still need to send each probe /scale off to be individually calibrated to that same standard?

 

Kind Regards

 

Dave

 

Based in the UK

In my BRC experience,  yr externally calibrated items represent yr master units and can be used internally for calibrating scales and thermometers (although a master thermometer calibrated at 0degC would not necessarily be useful for calibrating another thermometer used at 90degC).

Thanks / Charles.C

Oh, the Aw question.

Your water activity machine should come with instructions as to how to calibrate.  I haven't used one for a while, but a decent reference book should give the Aw of various standard solutions, if that helps.

 

Regards,

Philip (UK)

What he said.  It's hard for an auditor to argue with your calibration method when you are following the manufacturer's instructions.  For any piece of equipment.

Martha

Yeh i figured that my logic was ok on this subject, if my weights are calibrated to a standard and my internal scale calibration checks with corective actions in place are undertaken with those weights, which are traceable to a standard i cant see any argument.

Same with probes, intersting point about 0 degrees and 90.. however i would logicaly only use a master reference probe that has the same operating range as the units to be calibrated against. if i had a special probe operating at 90 > 250  i would need or / use a reference probe calibrated with the same operating criteria.

as far as Aw machines, moisture balances scales and probes, they all come with instructions for internal calibrations (manufacturers instructions) but where they instruct to calibrate weight for example the moisure machine says it shouldnt need doing in normal operation but its a 30 second task to calibrate and would NOT be to a standard with exception to the fact that the weight used IS to a standard. Aw machine came with some test solution i need to read up on to see hwo this is done but as far as i know the solution albeit from the suplier rotronic is not traceable to a recognised standard. so i guess my only course of action there is to send away.. and that this so called test kit would only be used based on risk for internal monitoring during that year. to highlight when or if the unit has deviated. (like testing probes and scales but not to a standard traceable point)