Method and structure for enclosing a packaging machine

An enclosing structure for a packaging machine, said packaging machine including at least two work portions having different operational tasks, arranged one after another along a packaging line of said packaging machine, the enclosing structure comprising:

• enclosing panel-shaped means assembled together to form at least two enclosing chambers for protecting each of said two work portions arranged one after another along said packaging line during operation of said packaging machine, a first enclosing chamber enclosing an environment at a pressure higher than an outside pressure disposed about a work portion requiring said pressurized environment and a second enclosing chamber enclosing an environment with a pressure equal to the outside pressure disposed about a work portion located upstream or downstream of said first portion along said packaging line;
• means for generating at least one flow of high pressure air delivered only into said first enclosing chamber for maintaining a pressurized environment therein, and wherein said high pressure air is the only source of air supply that enters the first enclosing chamber;
• passages only provided in said second enclosing chamber between the first enclosing chamber and the second enclosing chamber, the only air entering the second enclosure being permitted to pass solely from said first enclosing chamber with the pressurized environment to the second enclosing chamber with the pressure equal to the outside pressure;
• suction means for withdrawing air from an inside of said second enclosing chamber in an amount sufficient to maintain the pressure inside said second enclosing chamber substantially constant and equal to the outside pressure, during operation of said work portions within the enclosing structure;
• means cooperating with said generating means and with said suction means for purifying a flow of air at an outlet of said second enclosing chamber.