2. Rigorous sealing

2.1 By deformation

A flexible, easily deformable metal member is welded or brazed to each of the moving and fixed surfaces. The result is a displacement force which is generally proportional to the stroke.

A first solution is to use a thin membrane, from a few hundredths to one or two tenths of a millimeter thick, generally corrugated to give it greater flexibility (figure 2 ). The stroke is very short, on the order of a millimeter, as are the possible pressures, on the order of fractions of a megapascal. A single membrane is rarely used.