Back Flow Preventer

[boze]

Installing a potable back flow valve system, and have seen some systems with a strainer ahead of the valves.
I do not see this addressed in the plumbing code.
Some systems include a strainer, and this seems to be practical.
Ideas and comments will be appreciated.
Current plan (by others) is to not use a strainer.

 

[PEDARRIN2]

If you are referring to a reduced pressure zone type backflow, a strainer is a good idea because sometimes there is small gritt/particles in the domestic water from the main.

This particulate matter can sometimes slightly foul the operation of the check valves so they do not close completely and cause small discharges from the relief in the reduced pressure zone of the backflow (the area between the two check valves).

It is mainly a nuisance issue that causes owners to wonder if there is something wrong with the backflow preventer.

Refer to the following,

http://media2.wattswater.com/0834246.pdf

 

[IRstuff]

"This particulate matter can sometimes slightly foul the operation of the check valves"

BTDT, just last year. My city requires every house to have a backflow preventer, which is required to be inspected every year. Naturally, that winds up being the only time it's actually operated, and naturally, debris gets into the valve and causes it to leak. Oddly, we don't have a requirement for a strainer. And, naturally, the typical plumber doesn't carry parts for repairing said valves; you have to get the authorized backflow inspectors, whose day job is repairing and installing said valves.

TTFN
faq731-376

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[PEDARRIN2]

Putting backflow preventers in residential settings are becoming more prevelent and in my opinion - a good idea.

USC did a study on the level of cross connections in residential areas and it almost makes me want to only drink bottled water (

http://media.wattswater.com/PrevalenceofCross-Connections.pdf).

And when you look at what happens in commercial/industrial settings and think, "something like that could happen in my neighborhood" - it almost makes me want to put one in myself.

Most residential plumbers would not have the training to test/repair backflow preventers. But most commercial plumbing contractors with service departments would have the appropriate training.

 

[boze]

Thanks to all for responding.
Responses provide very satisfactory viewpoints.