Backflow preventer on existing 6" main

[sjp8]

I am working on a redevelopment project and am trying to re-use an existing 6" water main that is looped through the site to an existing 12" main located in the County Road (NY). The water utility currently owns the 6" main, but, the developer is taking over the site and therefore the line must become privately owned if it is to be kept in operation. The water utility is requiring that we install vaults at the property line at each end of the main. Each vault is to be equipped with a DCV and meter. I am used to splitting fire protection and domestic within the vault, however in this case, I would like to design a configuration that has a backflow preventer and meter in series on the same line.

Does anyone have any information on how this should be configured or know where I could learn more?

Thanks.

 

[Alpheus411]

I've seen a number of sites with domestic & fire on the same line, they use a dual service meter, also called a combined meter, bypass meter, fireline meter or simply master meter, such as this one:

http://www.herseymeters.com/prod_fire.html

Then they just connect it to whatever type of backflow preventer they need. I'm not sure about the logic they use in determining the order in which to put the dual meter and BFP in though, or if it matters much. I've dealt mostly with utilities that specify exactly how they want their master meters done.

 

[PEDARRIN2]

If the 6" is looped then flow can occur in either direction - thus the requirement for pits at both ends.

A dual check valve backflow preventor can be used for fire water service and can be put in a pit. But if your jurisdiction requires a reduced pressure principle backflow preventor for the domestic water - those cannot be placed in a pit. You might want to check what is required.