Versions:

• Mod: 1.1.6
• MC: 1.20.1
• Forge: 47.3.12

I did a test with the turbine because I was not able to close the steam/water cycle. I would understand if a little water disappeared, but here the entire tank from Mekanism disappears in a moment. Video from the test: https://youtu.be/h4gO0Dss-Uw

From 1,000,000 mb of steam, only 42,000 mb of water remained.

JEI also shows that should be 1:1 :

Note: Look at screenshot. In JEI process name translation is missing.