Systems that are intended to prevent pressure equalisation between two chambers at different pressures and that are connected together by gaps. For this purpose non-contact seals (gap seals) or - more often - contact seals are used (Figure D 16).
In relation to the layout and loading a differentiation is made between hydraulic seals and pneumatic seals.
![8909ee435410d4de98e634516805ddcac6180fcd 0001_dichtungen.gif](/fileadmin/smc/files/8909ee435410d4de98e634516805ddcac6180fcd.gif)
Figure D 16: Categorisation of seals