If there is a slight gap in a duckbill when it arrives, please be rest assured that it is NOT defective. After extensive testing with a pressure gauge, we found the breast pump suction was not compromised at all.
However, duckbill valves will lose suction with regular wear and tear. Replace them every 1-2 months to ensure optimal performance. Another way to know if your duckbills need to be replaced is by doing this test:
When all your pump parts are properly assembled and your breast pump is turned on, the duckbill will pull closed at the tip. However, if the duckbill looks 'floppy' and is not closing properly when your pump is on, it needs to be replaced.