Waste tank
From Unofficial Stationeers Wiki
Waste tank is one of the vital tanks you have in your EVA Suit. When it is full it will cause the filters to stop working and you will suffocate. Keep it below 4000kPa. When your tank gets near 4000kPa then it will cause LowOxygen cautions then CriticalOxygen cautions so it can suffocate you! Watch out for its pressure!