Circumferential seal for a vacuum pressure chamber on a metering device

A metering device having a vacuum pressure chamber formed between a stationary trough-shaped casing and a revolving transporting disk, the device comprising:

• an annular support body made of air-impermeable sealing material arranged along an inside of the trough-shaped casing, said support body including;
• (a) an outer edge provided with a recess and forming a step-like cross-section,
• (b) a first surface spaced from the transporting disk by a first distance,
• (c) a second surface, recessed from said first surface, and spaced from the transporting disk by a second distance, greater than said first distance, and
• (d) an outer side extending and conically expanding from said first surface to said second surface, said outer side and said first surface jointly forming a corner;
• an O-ring having a cross-sectional diameter greater than said first distance and less than said second distance;
• said O-ring being made of air-impermeable, elastic material and loosely resting on said outer side and said second surface and spaced from the transporting disk by a small distance when vacuum pressure is not applied;
• and
• when vacuum pressure is applied to the vacuum pressure chamber, said O-ring presses toward the space between said first surface and the transporting disk and away from said second surface, said O-ring makes linear contact with both said corner of said support body and the transporting disk, whereby relatively low frictional forces are generated by said O-ring on the revolving transporting disk.