Dear colleague,
In my opinion there is some misunderstanding in the side of the auditor
you are mentioning. I do not know the characteristics of the equipment you
operate, but I think it is based on detecting deformations of a magnetic
field when a metallic body (ferrous and non-ferrous?) pass through it. Since
it is not possible to foresee what type of metal piece could come as hazard,
modern metal detectors are adjusted to detect all of them, and reference is
made to the size of metallic pieces that could be detected rather than to
the material.
The metallic spec ("the hazard") that could eventually pass unnoticed
(to the machine) shall have a size that could pass, in turn, undetected to
the consumer and will not harm him or her, this size will be taken as the
"critical limit".
Therefore what the machines are really controlling is the size of the
metallic piece right above the size that is considered harmful. For modern
metal (HACCP) detectors therefore it is important the size of the
calibrating balls.
In your case you have them in a plastic pellet, therefore they are not
wear off by use and they measure the same as the beginning therefore no need
of "calibration" for them, till the plastic wear off and you may find
necessary to buy some new reference probes.
If the machine does not detect the small ball taken as the minimum
detectable size (your "critical limit") then you are in trouble, and you
have a problem with your machine. This is the reason for the calibration you
are doing (and must do). In this case you are doing two operations in one.
Verification, that the machine is operating detecting metallic pieces and
simultaneously calibrating against a reference size.
Sometimes due to ignorance or lack of standards probes, people is using
a simple not calibrated metal piece (e.g. a pen) to test that the metal
detector is functioning, but this is incomplete and risky, HACCP auditors
can in this case ask for "calibration", and the calibration refers in this
case to the use of the calibrated (by size) balls you are mentioning to use.
But this is not your case.
What should be important for HACCP auditors is to see if you have a
record (the samples) of metallic pieces actually found in the products. The
samples are an indication that the CCP is working. Moreover, they are a good
indication for internal HACCP audits from where this type of problems could
come (from nuts and bolts of the machines to beer caps).
HACCP is for preventing problems to happen, not just to keep records and
make inspectors and auditors happy given prescriptions. Prevention in this
case could imply proper maintenance programmes on machines, a SSOP for
maintenance and repair people (not in the regulations but important for this
kind of hazards), proper monitoring of activities by employees (e.g.
drinking in handling and processing areas, use of paper clips, etc). What to
do will be said by the metallic pieces you detect.
Kind regards.
Hector M. Lupin
Senior Fishery Industry Officer (Quality Assurance)
Fish Utilization and Marketing Service
Fishery Industries Division / FAO of the UN
Viale delle Terme de Caracalla 00100 Rome Italy
Tel.: +39 06 570 56459 Fax: + 39 06 570 55188
E-mail: hector.lupin@fao.org
Please visit our website: http://www.fao.org <http://www.fao.org/>
-----Original Message-----
From: Michael Graz [mailto:MichaelG@ij.co.za]
Sent: Monday, February 18, 2002 1:25 PM
To: Seafood HACCP Mailing List
Subject: Metal Detection
Dear All
In our factories we metal detect all finished products leaving the
factories, in some cases we metal detect incoming raw material. We verify
that the metal detectors are functioning on an hourly basis using test wands
of set sizes obtained from the suppliers of our Metal Detectors. These test
wands are plastic strips with a metal ball of predetermined sizes set in
Perspex at one end.
At a recent regulatory HACCP audit we were asked about calibration of these
test wands, how often we do it and they wanted calibration certificates. I
have never been asked this by any other auditor and have never heard of this
being done, so my question is: Does anyone have any information regarding
this matter that would help clarify the situation for me? If anybody has
had their test wands calibrated, how did you go about it?
Regards
Michael Graz PhD
Quality Assurance Manager
Irvin & Johnson Ltd.
P.O. Box 4804, Cape Town, 8000, South Africa
(Tel) ++27 21 440 7955 (Fax) ++27 21 447 0601 (Mobile) ++27 82 652 2079
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