Method for determining the degree of wear of a valve, and apparatus for carrying out said method

A method for determining the degree of wear of a valve, wherein

• the degree of wear of the valve depends on the degree of wear of an expandable material operating element present inside the valve,
• the expandable material operating element performs a mechanical movement with each change in temperature, which mechanical movement leads to wear and
• the expandable material operating element is connected mechanically to a piston,
• characterised in that
• the movements of the expandable material operating element (3) are calculated by initially detecting the change in temperature on the expandable material operating element (3),
• whereupon the changes in the temperature are converted into movements on the basis of the temperature/movement curve applicable to the expandable material operating element (3) and
• the degree of wear of the expandable material operating element (3) is calculated from the quantitative sum of the movements.