FREQUENTLY ASKED QUESTIONS ON METALDETECtORS
The installation of a metal detector on a production line is mandatory?
The continuous contact between the products and the metallic machinery is the most common cause of food pollution. In Italy the current normative is the Law Decree n. 155 promulgated in 26/05/1997 that imposes the control of all critical phases of the productive cicle, according to the HACCP directives.
Unobservance of such normatives can result in costly fees. Moreover, many mayor
distribution companies of the food industry requests to their suppliers the presence of metaldetectors in the production line.
The use of metal detectors protects not only the final customer, but the productive facilities
too, avoiding serious and costly damages.
What are the control procedures generally adopted?
Every mayor distribution companies, italian or foreign, requests to their suppliers a costant check of the functionality of the metal detectors.
For this is necessary to periodically check, using certified thets spheres, the revelation capacity of the metal detector. This check is normally made at the start of every productive cicle, and the result of the test is written down.
Higher security levels can be achieved by making a test botth at the start and at the end of the production, and if the final test goes wrong all products should be re-cheked once the metaldetectors functionality has been restored.
Is the detection limited to ferrous materials only?
No! Every metallic alloy, and thus even non-conductive alloys like steel, copper or aluminnium, can be detected by a metaldetector.
Stainless steels, of wich the most videly used are the 304 and 316 alloys, are amagnetic and possess a low conductivity, so their revelation is harder. To minimize this problem, Metalim uses an high frequency magnetic field, and so can detect this materials with relative ease.
Are the frequency used by metal detectors harmful to people?
The magnetic field of a metal detector is not dangerous for people due to it's low intensity, it's high frequency and it's screening.
All Coel's metal detectors are certified according to the 89/336/CEE directive and updated to the 92/31/CEE directive of the council in date 28 april 1992. Al metaldetectors are realized in conformity to the ETS 300683 - RES 9 normatives.
What are the tipical applications of an industrial metal detector?
"Metalim' can be used in every sector of the food industy: dairy, canning and perserves, meat industry, production of pasta, oil industry, rice, ice creams, frozen products, sweets and shugar, spices, fruit and vegetables, catering, ecc.
Which factors affects the operative senitivity of a metaldetector?
Some products, like fresh meat, cheese or freshly baked bread can influence metal detectors. Is thus necessary set the metal detectors to the best sensitivity for everty phase of the production cicle.
- The dimensions of the opening: the bigger the opening, the lower the sensitivity.
A rule of thumb generaly adopted is that a metal detector can detect
easly a sphere which diameter is 1% of the opening, meaning that a
10 cm opening allows the detection of a 1 mm sphere. Higher
sensibilities are, however, possible.
- The position of the contaminated product in the passage:
The sensitivity is minimum at the center. All our declarations of sensitivity refers to the centre of the passage.
- The kind of product:
products that are particularry hot, wet or big generates a bigger perturbation.
- Ambient condition:
vibrating parts, nearby maetallic masses, unstable installations are all factors that can induce false allarms.
Our installations uses particular tecniques to minimize perturbations.
- The speed of the product:
The optimal working speed is between 10 and 60 mt/min. Working outside this ranges is possible in particular applicazions.
Once spotted, is possible to reject only the contaminated product?
"Metalim" can command every kind of rejection sistem. It can also be connected to optical or acustical allarms, or to weighting systems. "Metalim" is free from false allarms, and has an high sensitivity and selectivity. On
piping, Metalim can be fitted with a pneumatic valve that rejects the contaminated part of the products.
Who sets and regulatie the metal detector?
COEL follows the client in the installation and use of the metal detector.
A correct setting of the metal detector is of key importance. The settings must be made according to the product characteristics to obtain the maximum sensitivity. This setting can be done at the installation or at our production facility. Frequent checks must also be made to verify the correct sensitivity using the test spheres.
Metal detectors alimentari