Flexible reducing coupling acceptable in a drinkable water storage tank

Hello everyone,

Anyone know of a flexible reducing coupling that is acceptable to be used for drinkable water? I need to make a tight seal between a 4'' stainless steel pipe and a 3'' PVC inside a water storage tank.

Thanks,

Luc

If it's under pressure the answer is no.

There will not be any pressure. All we need is a tight seal. We want to pass the 3'' PVC right throught the 4'' stainless steel coupling and out of the tank. On the other side of the tank we will continue with the 3'' PVC pipe.

I checked the Fernco rubber coupling but they are not accepted for drinking water.

Luc

They are not accepted because generally potable water is under pressure. In your case though it should be fine.

It is NOT the pressure that makes it suitable, it is its construction and the materials used. Anything for that application would have to have a NSF seal, and Fernco's, because their normal use is for sewers, do not even make a submittal for testing. "Dresser" couplngs are potable water rated, and come in reducing sizes, sometimes the reduction is in their construction and other times by the use of reducing gaskets.

Well yes, but I doubt there is anything in the rubber that would cause a problem health wise. But, having tried to use one for a temporary repair I can attest to the fact that under pressure they blow up like a balloon and pop.

Thanks hj and Peter. I google searched and called several of our suppliers without a suitable solution.

We will use an alternative solution.

Kind regards,
Luc

You did not call the RIGHT suppliers then. Here, I could have what you need from about 6 different suppliers in a matter of a couple of hours depending on how far I would have to drive to each one.

FERNCOs are made of elastomeric PVC. PVC itself is pretty safe, it is the plasticizer that is in question.

https://www.fernco.com/sites/default/files/literature/SDS-997596-020315.pdf

If the fitting will be submerged in potable water I probably wouldnt use it. But if it will only be making the tiniest bit of contact on the inside of the fitting Id say go for it.

As an aside, I have used Fernco couplers on the suction side of 1/2 HP well pumps, which also receive 50 psi pressure when the pump kicks off. This was only used temporarily to test pumps, but it did hold up and made a perfect seal under suction and pressure. I added a few extra clamps and a lateral steel cable just in case.