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e654562

Active Member

Posts: 5

Location: USA

1

Friday, April 13th 2007, 5:33pm

1" vs. 3/4"

I am looking at purchasing a backflow device for my sprinkler system since the ones installed currently are junk.. I am looking at the Febco 850 and am trying to figure out what size to purchase 1" or 3/4". The line after my meter is 3/4".. Would it hurt to install a 1" one?
Thanks,
Bill stork

drpete3

Supreme Member

Posts: 376

Location: USA

2

Saturday, April 14th 2007, 5:53am

is it 1 inch coming into you back flow? It wont hurt to use 1".
Thanks,

Pete

e654562

Active Member

Posts: 5

Location: USA

3

Saturday, April 14th 2007, 12:01pm

No.. the feed after the meter is 3/4".. I could change the T in the 3/4" and convert to 1".. or I could leave the current T which is 3/4" all around.. which way is best?
Thanks,
Bill stork

Wet_Boots

Supreme Member

Posts: 4,057

Location: Metro NYC

4

Saturday, April 14th 2007, 3:35pm

Three quarters. Backflow capacities are way beyond those of the pipe sizes they possess, just like water meters.

e654562

Active Member

Posts: 5

Location: USA

5

Saturday, April 14th 2007, 4:57pm

would it hurt to u se 1"
Thanks,
Bill stork

Wet_Boots

Supreme Member

Posts: 4,057

Location: Metro NYC

6

Sunday, April 15th 2007, 6:15am

About as much as it would hurt to use inch-and-a-half. Understand that many backflow preventers of the 3/4" and 1" sizes are actually identical castings, only differing by the size of the pipe thread and valves on the unit.

e654562

Active Member

Posts: 5

Location: USA

7

Sunday, April 15th 2007, 11:16am

Sorry to be stupid about this. does that mean yes or no.. A friend of mine gave me a 1" today for free and wanted to know if it would be ok to use. i figured it should be fine since all valves and manifold are 1"..
Thanks,
Bill stork

Wet_Boots

Supreme Member

Posts: 4,057

Location: Metro NYC

8

Sunday, April 15th 2007, 12:06pm

I'd say use it in good health, but if you haven't figured that out by now, I would be politely inquiring whether you actually know whether this gift backflow preventer is of a type that is actually approved for use in your state/town/whatever ~ A Febco 850 is a Double Check Valve Assembly, and those are not toxic-rated, and are therefore unusable where protection from possible toxic backflow is required. Learn what the plumbing codes/laws are where you live, then make your decision.

HooKooDooKu

Supreme Member

9

Monday, April 16th 2007, 5:25am

Based on what I've learned at www.irrigationtutorials.com, the only thing to consider between a 1" v. 3/4" backflow is pressure losses. Each backflow will have a different pressure loss graph (pressure loss v. flow rate). These graphs are NOT strait line graphs. They actually are very curvy, and frequently have a "sweet" spot where they lose the least amount of pressure. If the flow rate is higher or lower than the "sweet" spot, there will be a greater pressure loss. Now sometimes these pressure losses don't amount to much of anything, and if you've got pressure to spare, then you don't care. If you are borderline in having enough pressure to work with, then you'd want to review these pressure charts. Most manufaturers have them availible on their web sites. Well, I assume they do. When I was looking into WATT back flows, I had no problem finding them, and I THINK I even found Febco at one time too.

sprinklerdr

New Member

Posts: 2

Location: USA

10

Thursday, April 19th 2007, 5:06am

I'd have to agree with Wet Boots on this one. Sure would hate for you to install the backflow and then come home and your water was off because it's not the right one for your municipality. Heck, here in Columbus there are at least six different variations on code and enforcement, all based on the municipal code.

Should you decide to go with it, another option is to use 3/4 into the bottom of the backflow and then use a 3/4 sweat x 1" MIPT copper adapter as your transition to 1" on the inlet side, then 1" out.
Can't make it wet? Maybe I can help!

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