This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Polte Drosselklappe fr Turbinen. de Drosselklappe der PolteWerke scan from old catalogue unknown no remark at foto or masthead of publication publisher liquidated Armaturen PolteWerke Butterfly valves PDold Files by Wistula
Page 2023 Free-images.com. All images are Public Domain