Are duckbill valves supposed to have gaps?

If you want a high performance of non return function, then A good duckbill valve aren’t suppose to have gaps.

Let’s take take a look the structure of duckbill valve as followed pictures.

You could see that duckbill’s lip should stay close to prevent back-flow, and flow pass by lip’s opening.

And a fine gap is barely visible by eyes after cutting the lip, you could see the gap’s opening and closing from a 2.5D projector. You could check this video from YouTube:


Or you could know more info from site below:

Certainly in some cases, the users doesn’t care about small back-flow, then it would be alright. But I believe most of cases require no gaps to perform better.

Meanwhile there are many others reasons causing gaps, such as chemical, working times etc.Contact us to know more details of duckbill valve, such as flow data, chemical resistant, material report, ect . Our Email [email protected] , Phone/Whatsapp: +86 18359163977. Website: www.rubbervalve.com 

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Data of air/liquid flow, aging, high & low tempreture, chemical resistent test etc.

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