Check valve leakage

[Rudy]

I had a situation where High Pressure was backfeeding my Presoak line, and causing a line to separate in the equipment room. I found a bad 1/4" check valve (an ancient Paraplate with very worn poppet). I found a Fluid Controls 1/4" spare and reinstalled it. There's still some backfeeding....but not enough to blow the line.

I removed the Fluid Controls check valve, installed a new Teflon repair kit....and tested it with an air hose. It holds, but not perfectly. If you blow air into it, a VERY little bit still leaks.

I ordered some new ones from Kleen Rite. Guess what? They also leak a very, very small amount also. If I take an air hose and blow into the proper end.....a thumb held on the opposite end eventually gets lifted due to the small leakage. This doesn't seem right.

Here's my question. Do check valves have to "wear in" or need time to "seat".....or are these things faulty?

 

[mrfixit]

I find the fluid controls to be one of my favorites. Are you using the Teflon seal or rubber. Either may take a few shots at 1000 to get a perfect seal, Teflon probably a few more. They are designed for hp so a 100# isn't much to force it sealed. Plus designed for water. You have no water pressure forcing the poppet tight.

I like to stretch the springs a tad when rebuilding to help prevent siphoning. Though these aren't that much of a problem like the weaker ones.

When the hp is behind it, it shouldn't leak for you.

 

[Rudy]

Thanks. That's reassuring. Yes, I have the Teflon. That's why I was asking, since it's stiffer. I've had good luck with the 1/2" size. I was surprised to feel the air leaking with the Fluid Control, and not with the Paraplates......

 

[mrfixit]

Most of mine are 1/4" for chem to bay. Where the pp Teflon and new also? Its probably due to the seal design between the two. Flat seal or tapered. I think the tapered are a little better because as the seal wears it just gets tighter. I could be wrong.. They both have thier pluses and minuses.

 

[MEP001]

I've seen the same thing with the Fluid Controls Teflon seat valves - the high pressure will deform the seal and make it seat under pressure, but 1 PSI from blowing won't make it seat completely. I've had almost no trouble with the Fluid Controls valves.

 

[Ric]

I've seen the same thing with the Fluid Controls Teflon seat valves - the high pressure will deform the seal and make it seat under pressure, but 1 PSI from blowing won't make it seat completely. I've had almost no trouble with the Fluid Controls valves.

Do you use the teflon seats?

 

[MEP001]

Yes, I tried the o-ring ones first and the seals would sometimes come off. The teflon seals don't.