Method and Arrangement for Exhausting Gas from a Coating Material

A method for exhausting gas from a coating material comprising the steps of:

• feeding coating material to a bottom area of a drum rotating around an essentially vertical axis inside a vacuum tank, the vacuum tank having an inner wall, the vertical axis defining a radial direction and a height direction, wherein the drum has an inner wall with a plurality of steps;
• using forces created by rotating motion of the drum to cause the coating material to rise up the inner wall of the drum and flow over at least two of the plurality of steps;
• veiling the coating material over a front edge of each step to form a radially extending veil-like thin film of the coating material spaced from the inner wall of the drum, which extends between said front edge of the step to the inner wall of the drum;
• causing the coating material to discharge from an upper edge of the drum as a thin film against the inner wall of the vacuum tank so that the coating material flows downwards along the tank inner wall;
• and
• conducting the coating material out of the tank.

An apparatus for exhausting gas from a coating material, the apparatus comprising:

• a tank connected to a source of vacuum;
• a drum mounted for rotation around a vertical axis inside the tank, the vertical axis defining a radial direction and a height direction, and the drum having an outer surface;
• wherein the drum has an inner surface which has at least two steps levels formed of successive concave sections, defining front edges which determine the elevation of the step levels, the front edges arranged such that the coating material rising upwards due to the effect of the rotating motion will form a thin veil-like film of the coating material spaced from the inner wall of the drum, which extends between said front edges of the steps levels to the inner wall of the drum;
• a coating material feed pipe extending into the tank and positioned to discharge coating material into the drum;
• and
• an outlet mounted to the tank for discharging the coating material from the tank.