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Istorch

New Member

1

Saturday, May 1st 2010, 3:33pm

Back flow

Can a back flow device break

HooKooDooKu

Supreme Member

2

Monday, May 3rd 2010, 12:15pm

Just leave one out exposed to freezing temperature full of water and find out..... :)


So the simple answer is yes.

However what happens during a failure depends upon the type of device.
For example, an RPZ is designed such that if any component inside the device fails (say a check valve becomes stuck open), the device will still protect the water source by spewing water rather than allowing it to flow backwards.

By contrast, if the check valves in a simple duel check become stuck open, the backflow preventer is rendered useless (i.e. it no longer functions as a back-flow preventer).

Hunto

New Member

Posts: 2

Location: Copperas Cove Texas

3

Thursday, June 17th 2010, 11:47am

Back Flow Devices

I live in Central Texas Area where my local code requires the back flow devices to be above ground. Here is my problem:

I live on a hill with a steep sloping front yard. My water meter is at the lowest point in the side walk. Most of the articals I have read says the devise must be six inches above the highest sprinkler head.The installers installed a FEBCO Pressure Vacuum Breaker, model 765 at the bottom of the hill just above the water meter. I brought it to their attention that it must be 6 inches above the highest sprinkler head in the system. Now they want to install an Airgap device which I think must also be 6 inches above the highest sprinkler head. I don't know the make and model number yet. Can anyone give me advice.

Wet_Boots

Supreme Member

Posts: 4,088

Location: Metro NYC

4

Friday, June 18th 2010, 8:18am

an RPZ device can be installed at an elevation below the sprinkler heads.

HooKooDooKu

Supreme Member

5

Friday, June 18th 2010, 8:49am

If allowed in your area, a double check backflow preventer can be installed just about anywhere: above grade, below grade in a meter box, indoors, above sprinkler head, below sprikler head, etc. The only limitations to its placement is that you have to be able to access the test-cocks.

However, many consider a DC to be the least safe form of backflow prevention (hence why some areas do not allow them). They are totally unsuitable if anything is being injected into your irrigation water (i.e. fertigation... but for something like that, an RPZ is really a MUST).

One of the reasons DCs are considered less safe is that if trash in the water fouls up one of the check valves, there a really good chance the other check valve gets fouled at the same time. And if both check valves get fouled, then you don't have any backflow protection. One thing that can help, and is good for your valves and other equipement, would be to install a filter up-stream of your backflow. That was my solution, to get a 150 mesh filter suitable for mainline pipes. I do both lawn and drip irrigation with my system, and the filter provides filtration for the drip irrigation, and keep trash out of not only the DC, but the valves and drip irrigation system as well.

Hunto

New Member

Posts: 2

Location: Copperas Cove Texas

6

Friday, June 18th 2010, 6:33pm

Back Flow Devices

My installer ended up putting in a FEBCO 860 (RPZ) I hope that I dont have any problems with the device or the City Inspector. What kind of support, if any, is usually used as PVC is not that strong?

hi.todd

Supreme Member

Posts: 417

Location: Houston, Texas

7

Friday, June 18th 2010, 10:29pm

Usually some angle iron with holes in it and brackets. Try to support the metal and stay off of any PVC pipe.
:thumbup: :thumbsup:

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