In mechanical seals with secondary seals made of elastomers to seal gases and gas-charged media under high pressure, gas diffuses into the secondary seals. When the pressure is relieved, the gas reemerges. Sudden decompression causes explosion-like degassing; the surface of the elastomer is torn open at several places, destroying the sealing element. Gas adsorption and hence the risk of explosive decompression can be prevented by choosing suitable non-elastomers as the material for the secondary seal. It is better still to prevent possible violent decompression by taking appropriate control and/or process engineering measures.