User contributions
- 13:08, 12 March 2021 (diff | hist) . . (+40) . . m What is a vacuum valve
- 13:06, 12 March 2021 (diff | hist) . . (+33) . . m What is a vacuum valve
- 12:45, 12 March 2021 (diff | hist) . . (-20) . . m The definition of the vacuum valves