THE IMPORTANCE OF SEALS AS ELEMENTS OF CO NSTRUCTION

Sealing of moved machine parts demands the management of a large field of action because motionless positions have to be sealed reliantly as well as movement at different speeds. Besides one has to regard chang ing external working conditions, e.g. pressure and temperature. Seals composed of highly extensible elastomeric materials offer the possibil ity of adaptation to changing working conditions if there is a qualifi ed design. Deriving profit by using self-support effects will be possi ble only if the working effects of active and passive seals are well k nown and the engineer and the user upply them correctly. Concerning li fetime and reliability of elastomeric seals there are limits caused by aging and hardening of the material which weaken the described mechan isms of function. The steadily increasing requirement to better perman ence to high temperatures and more aggressive chemical additives while extending service intervals will demand to guarantee the reliability of sealing in the future by progress In material and a better seal des ign.