Caleffi 573 backflow preventer valve

NoelAnderson

Should you use some sort of plumber's grease or sealant on the gaskets of the 573 series backflow preventer valve from Caleffi? I can't find anything in the instructions and on the jobs I have used them on I have to keep going back many times and tightening their nuts due to leakage.

Thanks,
Noel

hot_rod

Are you getting the newer blue colored ones?  Those should seal without any sealant. The previous green ones work better if they are wet first.
All are compression set material, so don’t over tighten them.

NoelAnderson

Thanks Hot Rod. I don't know which color I got, but I will assume it is a green one. I have retightened every few days about six times. I installed them dry and there has always been a drop or two when I checked it, so I give the nut a twist with a wrench. Will the gasket keep expanding and eventually seal itself?

jad3675

I had the same issue with the 573, Caleffi thermostatic mixing valve and Caleffi PRV I have at my house - all with green washers.
I only tightened them to one 'ug' as I didn't want to risk damaging the washers or the threads.
I have a lot of wrench time with Italian motorcycles, so I assumed this was part of the charm.

Blue monster pipe dope on the threads has fixed the issue for me, though.

Is there a part # for the blue washers?

John

hot_rod

over tightening  seems to be the cause of most drips. One grunt should be plenty. Once they are compressed too much, time to replace.
Yes, I have heard of pipe dope being used. Too much could plug the screen however.

I’ll check on the blue version in that size, it’s a rolling change on all sizes.

Ironman

Soaking the gaskets for at least 15 minutes before using them has worked well for us. Rehau taught us to do that in one of their classes years ago because they use the same gaskets with their manifolds.