Depending on the products and packaging, the spheres must then be calculated. The formulas for calculating the spheres can also be found in the EN60079-10 standard. Calculating spheres does not prevent common sense. In the case of light gases (less dense than air) a cone-shaped ceiling with a suction at the highest point should be used. A flat ceiling without suction would create a danger zone! Conversely, in the case of heavy gases (denser than air), a suction system should be installed at the sump. Without suction at this point, the tank would become a gas containment area! The calculation of the spheres in the standard does not exclude common sense.<\/p>\n
You now have the zoning for your packaging line. A point on the ATEX electrical components.
\nThe electrical components chosen must be in line with the zoning in which they are located and depend on the products used. These are the symbols found on the product label. The labels of ATEX products will be the subject of a dedicated article. It should be noted here that ATEX electrical components are much more expensive than non-ATEX components. This is because the volume sold by manufacturers is low and the risk is very high in case of an accident. Over-zoning your line is therefore not a relevant or cost-effective solution. There are few cases where the entire process, from container manufacturing to truck loading, is ATEX.<\/p>\n
To limit zoning, one solution is very effective: ventilation. Once again, we must refer to the zoning standard EN60079-10. The table in this standard shows that even a zone 0 can be transformed into a non-zone with appropriate ventilation. To be successful in your packaging project, you should ask builders to install extraction points. Manufacturers with experience in ATEX liquid filling machines will tell you about them anyway. Information on gas units can be found in standard 80079-20-1.<\/p>\n
In your internal discussions and with the manufacturers, consider the location of the control cabinets. Ideally, you should have a control cabinet outside the ATEX zone. If an electrical cabinet is in an ATEX zone, its touch screen must, depending on the zoning, either be ATEX at the required zoning level, or be behind a window. If it is behind a window, the screen will not be touch-sensitive but will be controlled by buttons…. In many cases, it will be more appropriate to have two cabinets: one cabinet for the touch screen and any buttons, and one cabinet for the rest of the equipment (e.g. servomotor, PLC, etc.). The enclosure with the rest of the equipment must be either explosion-proof or overpressurised. Explosion proof enclosures are generally smaller.<\/p>\n
The disadvantage, due to their compactness, is the low heat dissipation. They are therefore not suitable for lines with more heat-generating components. For example, servomotors. On the other hand, overpressure cabinets consume energy continuously, and require purging (time) if they are opened before being closed again. In some factories, to overcome these limitations, the main cabinets are placed outside the ATEX zone as in a dedicated room, and the cabinet with the touch screen is in the zoned room.<\/p>\n