5 replies to this topic

[petratsitlak2]

Hello to All of you,

 

I need your advice again!

 

I have been asked to make a calibration of our sieves. Sieves' mesh size are set as CCPs for our HACCP study.

 

What I would like to know is, if the calibration must be done from external lab with UKAS accreditation or if I perform the UKAS method for sieve tests (in-house) will be also acceptable from a future BRC auditor.

 

Also, we use some filter-bags for filtering liquids; again, the mesh size of these bags is set as a CCP. Apparently, we cannot perform a calibration in this case. Instead, is it wise to ask from our supplier a CofC stating the pore size of the bag for each delivery or should we ask for an annual certificate of a test that they might be doing? What is the best practice in this case? Has anyone confronted something similar to that?

 

I don't have any prior experience,so any other advice/guidance relating to calibrations will be greatly appreciated.

 

Many thanks,

Petra

 

 

[MWidra]

I've been wrestling with this issue myself, though not for a CCP. Calibration of sieves is not easy. We use them to characterize the particle distribution profile of our products. I would wonder if, once your sieves are tested, that you could check their calibration at a set interval with some calibrated beads. Calibrated beads do exist, and if you can find two sizes, one that should pass through and one that should be retained, that it would show that your sieve is performing the function of removing unwanted material. Then you may need to purchase new beads after their expiration, but you would not need to have the sieve re-calibrated, which is expensive. No matter what you do, document your procedure so that the auditor can see what you are actually doing. And, of course, keep records. Hope others have ideas as well, I'm interested in seeing what they say. Martha

[MWidra]

And, as a word to the administration, the HTML function is not working for me.

[Wer3005]

This is possible to
Buy standarized sample with known particle size. Mayby this way is good to consider

[GMO]

I would say that validation does not equal calibration and people get into this quite a lot.  It is possible to calibrate what is retained on a sieve vs. what passes but what is the point after it has been installed?  Surely this should be tested or assured at delivery?  Is it likely to change post installation without visual damage (or measurable damage in the case of a filter)? 

 

If you think about a pasteuriser, I would calibrate the temperature probes and check for leaks because both of these things are likely to happen.  For a temperature probe, I know that the reading can drift.  For a sieve, unless it's broken, I can't see what's going to change?  It's also worth thinking about the micro risks of doing the tests.  To do it, you'd have to remove the sieve from your factory for a controlled trial, then clean it back in (sieves are tough to clean!) 

[giseladenise]

HI,

Your sieve must be purchased with a CoC at reception. then you need to make sure that mesh is the right one by measuring the holes in on inch (wide and length). you can use convertor tables to arrive to microns and validate with the sieve's coc.

 

Scientifically there are a lot of studies proving which are the particles sizes that will go through your sieves.

 

Hope this help.

 

GD