Water bubbles in flow sensor

Hi there!

I recently purchased the G1/4" Water Flow SensorSKU: TEM01071B, and have been trying to integrate it into a project where a user would drink through a straw. I’m having trouble with lots of water bubbles showing up, and im not sure where they are coming from.

Are these flow sensors air tight? Should they be oriented a certain way to release trapped air? Currently I have it in a vertical position.