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The last 2 posts

Monday, June 2nd 2014, 10:21pm

by hi.todd

good backflow questions, you probably know what I will say.

The PVB can be used in high hazard applications it protects against back siphonage, but not back pressure. The elevation in the sprinkler system can cause back pressure. That is why the PVB must be 12" above the tallest head and all piping.

The Double Check is ok for non Health hazard application or low hazard applications. It can handle back siphonage and back pressure.
Again it is low hazard. Check with local codes.

The RP is a great device that can handle high hazard, Back siphonage and back pressure. The RP Must be installed 12" above Grade. It absolutely can not be below grade. If water pressure is an issue, the RP can kill 10 to 12 LBS of your working pressure.

For more information on backflow issues check out BackflowInformation.com

Monday, June 2nd 2014, 9:13am

by andyl

Replace a Febco 765 with...?

I moved into a house with a 3/4" Febco 765 on the supply to the sprinker system, and found a crack in the input shutoff valve. As I have looked into replacing the part, I have discovered that as far as I can tell, a 765 should never have been used, because it is several feet below the highest part of the system. So I have a couple of questions:

What happens when a PVB is below the highest part of the system?

It looks like I need a double check valve assembly, e.g. a Wilkins 950XLT2 or 350XL, a Watts 007M3, or Febco 850. Does that make sense? Is there any reason to prefer one of these over any of the others (or is there a more commonly used model)? I'm in the Northeast, if that matters.



Thanks.