Stenner Duck Bills

[1Sammy]

Can some please help me with my thoughts on the operation of the duck bills. I see these as check valves.
So, there is one installed in the injector lets say. Return line pressure is 8 PSI. Pool pump on, stenner is off. 8 PSI pushes the duck bill closed and the pool water gets just that far. Stenner comes on and the pressure being greater than 8 PSI pushes the “valve” open and lets in the chlorine or acid. Am I missing something here guys ? Stenner shuts off after x minutes and the duck bill needs to close, but I see it having to “compress” for lack of a better word, the liquid between it and the stenner rollers. So it will not close unless there is a leak to drain off the pressure first? Writing this on a Monday so I might be brain dead from the weekend still..
Stenner tells me via email asking them if I can install a duck bill with a 25 PSI pump and they say no, it will not Stay closed at this lower 25 PSI . But But But, does not the pool return 8PSI close it ? I’m lost. Is there something magical in that 100 PSI injector so it works but won't with the 25 PSI.

 

[JohnT]

I don't think it takes any pressure on the pool water side to close the duck bill. It "wants" to be closed, and it only opens when the Stenner is pushing liquid through it. There will be very little pressure in the return line to your pool. The pressure on the gauge actually represents the pressure between the pump and the filter, and there will be a substantial drop after the filter.

 

[1Sammy]

Thanks JohnT.. So a spring in there ? I don't think so. What will cause it to want to be closed please. I have 8 PSI as i put a pressure gauge in the return line where the "Tee" is for the Stenner injector before i installed the injector. Thanks.

 

[JohnT]

The piece is made like a tube that tends to stay flat. Kind of like the roll up party noise makers. As long as there is more pressure inside than out, it opens and liquid flows. When outside pressure is equal to inside pressure the tube collapses, and when outside pressure rises above inside pressure it seals even better.

Check out Duckbill Valves, How they work! - Minivalve

 

[1Sammy]

Ah ha, easy enough once you know the answer JohnT, thanks much. Now i understand and also see where the duck comes into play, lol.
But, lol, always a but. I wonder why Stenner says the 25 PSI pump do not have enough pressure to keep them closed ? If anything should it not be enough pressure to open it, hummmm.. I like the idea of having this in the system but don't want to throw away my money if it will not work. Thank you.

 

[JohnT]

Ah ha, easy enough once you know the answer JohnT, thanks much. Now i understand and also see where the duck comes into play, lol.
But, lol, always a but. I wonder why Stenner says the 25 PSI pump do not have enough pressure to keep them closed ? If anything should it not be enough pressure to open it, hummmm.. I like the idea of having this in the system but don't want to throw away my money if it will not work. Thank you.

When Stenner talks about 25psi not keeping the check valve closed, they are talking about the pool water pressure. With the low line pressure the duck bill won't seal tightly.

The differences in Stenner pressure ratings are primarily the pressure into which the pump is injecting, not the pressure the pump itself creates. What makes those pumps different is the rating of the tube and the presence of some kind of check valve in the line.

The primary purpose of the check valve or duck bill is as a backup to prevent a leak if the tube on your pump splits. The pump itself is the primary seal between the pool water and the chlorine tank.

 

[1Sammy]

I read that a few times but still must be missing something, lol.... I told them my pool filter return line has 8 PSI at the injection point. I tested that with a pressure gauge. Now that i know what that duck bill is and how it works i can not understand why a 25 PSI Stenner will not work with it but a 100 PSI will. Anyone with a 25 PSI using a Duck Bill with there Stenner ? Thank you.

 

[trivetman]

You’re confused about the difference between 25psi and 100psi stenners. The only difference is the 100 psi version has the duckbill. The duckbill isn’t needed for injecting into a plumbing system lower than 25psi as the rollers and tubing will stand up to the pressure. For injecting into a system higher than 25psi the duckbill keeps the high pressure away from the stenner tubing and rollers. Its not the case that the duckbill wont work in lower pressure - its just not needed.

the duckbill can serve as a check valve in lower pressure systems but I understand its not exactly leakproof. I think that is consistent with what others have said in this post.

 

[1Sammy]

You’re confused about the difference between 25psi and 100psi stenners. The only difference is the 100 psi version has the duckbill. The duckbill isn’t needed for injecting into a plumbing system lower than 25psi as the rollers and tubing will stand up to the pressure. For injecting into a system higher than 25psi the duckbill keeps the high pressure away from the stenner tubing and rollers. Its not the case that the duckbill wont work in lower pressure - its just not needed.

the duckbill can serve as a check valve in lower pressure systems but I understand its not exactly leakproof. I think that is consistent with what others have said in this post.

hummmm.. So what you are saying no one here with swimming pools need a duck bill ? I like the idea of having one as a check valve that will cut down somewhat at least the pressure in the pool return line squirting 8 PSI of water out through a 1/4" broken line if it should happen.

 

[trivetman]

hummmm.. So what you are saying no one here with swimming pools need a duck bill ? I like the idea of having one as a check valve that will cut down somewhat at least the pressure in the pool return line squirting 8 PSI of water out through a 1/4" broken line if it should happen.

it probably is true that no-one “needs” the duckbill. I haven’t read about anyone running a pool at that high psi - especially after the filter. I put it on mine to provide a backstop for the reason u r saying - just for insurance. I think the downside to them is they can clog up and need replacing. I am on yr 1 of having it so I am not speaking from experience.

 

[1Sammy]

I finally Got IT. Sorry guys for being so delayed in catching on for what you are saying. Now that i know what that set of lips, aka duck bill is and how it works i Finally understand. I was Stuck on the 25 PSI as the Stenner 25 PSI pump, but that is NOT the case. The 25 PSI is what is needed on the POOL side to keep the duck bill closed to be effective enough for no water to get out. ( as you guys said above ) Stenner does not supply the injector with a duck bill with the 25 models as they are injecting into low pressure. They supply them with the 100 PSI pumps as they are used in lines much greater then what we use in our pools. What threw me off is the post i have read on here about the 100 PSI Stenner guys and using duck bills. I just figured i needed one for my 25 PSI pump.
All this as the guys said above, i was STUCK on thinking 25 PSI "pump" would not work with the duck bill, SORRY...
Installing one for the use of a check valve will protect that line and as i understand will block the pool water for most part from escaping. WOW, lol.. daaaaa on me.

 

[trivetman]

I finally Got IT.

Knew u could do it!!!