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Attention! Irrigation Backflow Prevention Devices


mgbinspect
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Greetings all!

I'm calling on the brain-trust for a little help.

Last week, I called out a backflow prevention device on a lawn sprinkler system as being the wrong design for the application. My opinion was based upon some old (dusty) information. And, the relocation company is refusing to "further evaluate" unless I can give them more definitive information regarding my opinion.

I've been googling to find information to support my opinion/suspicion. I'm pretty sure I'm right, but not yet thoroughly convinced. So, I'm teeing this subject up for a couple of reasons:

1. To get confirmation that I'm on target

2. So information on the subject is available to others

Here is the backflow prevention device in question:

Click to Enlarge
tn_201010228543_DSCN0904.jpg

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This particular unit is located in a crawl space - considerably below over half of the sprinkler heads - by as much as ten feet in some cases.

Now, it is my understanding that this style of backflow prevention device (with an apparent air gap design) is NOT to be used below sprinkler heads, and must be a minimum of 12" above the highest head.

Here is a link to "similar" unit, but not the exact unit. Unfortunately, the system is an hour and a half away and I didn't realize I might need to have the actual unit manufacturer and model number. I actually don't think it will be necessary, as "air gap' style units, in general, fall under this restriction (I think... that's why I'm here... to find out for sure).

Here is a great general information link from the EPA that might be useful in our library.

In short, it's my understanding that when the device is below the heads, "Pressure Vacuum Breakers" are not suitable. In such cases, "Reduced Pressure Principle Assembly", or possibly the "Double Check Valve" design, is required. But, the EPA document doesn't clearly spell that out. (The first link above, however, does).

So there you have it. What I'm hoping for is that one of you guys is intimately familiar with lawn irrigation systems and can nail this one down for time and eternity. A simple confirmation will be nice, but I think that, if anyone is so versed, a thorough educational response about this subject, in detail for the sake of readership, would be FANTASTIC!

As always, thanks in advance for your assistance and I hope the general readership benefits from the thread.

All the best,

Mike

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Now, I don't do sprinkler inspections so I'm certainly not trying to imply I have knowledge of your issue, however the EPA document references ASSE Standard 1020 for information on PVBs. Here's a link where that can be purchased, and in the description of it, it states they can't be used where backpressure on the assembly can be present. I would think head pressure from higher sprinkler heads would count as that, but not sure. Here's the link to the standard:

http://stores.assewebstore.com/-strse-1 ... Detail.bok

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The vacuum breaker on a lawn irrigation system must be no less than 6" above the highest sprinkler head. Now where that is printed, I do not know.....

Yet, there is a style of backflow preventer that is suitable when installed below the heads. So, it's not an all inclusive rule. I take it you are referring to the design I have in my photo, as opposed to a different design?

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Bad install. Must be 12" above highest outlet. That device is subject to siphoning.

That's what I'm thinking, but there is a device that could be installed in that location, Yes? My biggest problem is that I'm going on probably twelve year old info from a lawn sprinkler guy I spoke to on site...

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Looks like a watts device

http://www.nobackflow.com/irrigpam.htm

Hmm... that link suggests that EVERY style must be above the sprinkler heads. Can that be right? I see them below the heads, quite often - just not the design in the photo...

On second look, I see that what you posted is PERFECT! I didn't notice that the reference point on some of the devices was the earth and not the heads.

And, what is equally invaluable - I see "DOUBLE CHECK VALVE ASSEMBLY (DCVA)" units all the time. I had no idea that they're no longer allowed. And, since many areas of the country require an annual inspection of the device, we should probably be calling out the presence of such units. A report modification is in order!

THANK YOU CHARLIE! YOU ROCK!

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Thanks for that link, Charlie. Good work!

I went to that site and had a live chat with a representative. Here is that chat:

"Please wait for a site operator to respond.

You are now chatting with 'Celia'

Celia: Thank You for contacting Sprinkler Warehouse. How may I assist you today?

you: Hi! I'm assuming that Series 800M4QT Anti-Siphon Pressure Vacuum Breakers are not acceptable installed below the sprinkler heads. Is that correct? I've found one installed a good ten feet below the highest heads. It needs to be changed out for a different unit. Correct?

Celia: That is correct.

you: Thanks!

Celia: My Pleassure. Have a great day!

Celia: Is there anything else that I can help you with?

you: no thanks"

I've modified the thread subject line to make it easy to find for future reference. Again, good work Charlie. Have a great day and weekend.

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Why not just look up this issue in your local plumbing code? The answer to pretty much every question you've asked is in there.

The problem with trying to use these threads for future reference is that they tend to fill up with as much misinformation as anything else.

If you call the manufacturer, Celia might tell you one thing on Monday, and Roger might tell you a completely different thing on Tuesday.

The local plumbing code has the advantage of not being a moving target. If you don't have a local plumbing code, you could use one of the model codes, like the IRC or the UPC. Either way, you've got a solid basis for the information.

For those who are interested, go to section 603 of the UPC or section 2902 of the IRC to learn pretty much everything you need to know about backflow protection.

And, for the Oregon inspectors, double-check backflow valves are still approved here for sprinkler systems.

- Jim Katen, Oregon

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Why not just look up this issue in your local plumbing code? The answer to pretty much every question you've asked is in there.

The problem with trying to use these threads for future reference is that they tend to fill up with as much misinformation as anything else.

If you call the manufacturer, Celia might tell you one thing on Monday, and Roger might tell you a completely different thing on Tuesday.

The local plumbing code has the advantage of not being a moving target. If you don't have a local plumbing code, you could use one of the model codes, like the IRC or the UPC. Either way, you've got a solid basis for the information.

For those who are interested, go to section 603 of the UPC or section 2902 of the IRC to learn pretty much everything you need to know about backflow protection.

And, for the Oregon inspectors, double-check backflow valves are still approved here for sprinkler systems.

- Jim Katen, Oregon

I suppose some good came of the thread - the unit that is installed all over the country that is no longer approved.

I didn't realize that the code would get so specific, regarding types of backflow units approved based upon being above or below sprinkler heads.

If that's the case, you're probably right - there's no point in making TIJ a resourse for information that is readily available. I'll try to keep that in mind regarding future posts, Jim.

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I suppose some good came of the thread - the unit that is installed all over the country that is no longer approved.

I didn't realize that the code would get so specific, regarding types of backflow units approved based upon being above or below sprinkler heads.

If that's the case, you're probably right - there's no point in making TIJ a resourse for information that is readily available. I'll keep try to keep that in mind regarding future posts, Jim.

I don't mean to discourage questions or discussion. I'm just surprised that, in all of the responses that I saw, no one mentioned the most obvious resource for the answer to the question.

- Jim Katen, Oregon

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From the IRC

P2902.5.3 Lawn irrigation systems. The potable water

supply to lawn irrigation systems shall be protected against

backflow by an atmospheric-type vacuum breaker, a pressure-

type vacuum breaker or a reduced pressure principle

backflow preventer. A valve shall not be installed downstream

from an atmospheric vacuum breaker. Where chemicals

are introduced into the system, the potablewater supply

shall be protected against backflow by a reduced pressure

principle backflow preventer.

The height for the valve above the system or sprinkler head is not given in the IRC. I guess it defaults to the manufacturer?

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From the IRC

P2902.5.3 Lawn irrigation systems. The potable water

supply to lawn irrigation systems shall be protected against

backflow by an atmospheric-type vacuum breaker, a pressure-

type vacuum breaker or a reduced pressure principle

backflow preventer. A valve shall not be installed downstream

from an atmospheric vacuum breaker. Where chemicals

are introduced into the system, the potablewater supply

shall be protected against backflow by a reduced pressure

principle backflow preventer.

The height for the valve above the system or sprinkler head is not given in the IRC. I guess it defaults to the manufacturer?

The IRC defaults to the "applicable standard" at the right column of Table 2902.3. The UPC is more helpful. Its analogous table is 6-2. The far right column in that table gives specific heights for each type of backflow prevention device. For atmospheric vacuum breakers and spill-resistant pressure-type vacuum breakers, the distance is 6". For Pressure vacuum breakers, the distance is 12".

- Jim Katen, Oregon

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From the IRC

P2902.5.3 Lawn irrigation systems. The potable water

supply to lawn irrigation systems shall be protected against

backflow by an atmospheric-type vacuum breaker, a pressure-

type vacuum breaker or a reduced pressure principle

backflow preventer. A valve shall not be installed downstream

from an atmospheric vacuum breaker. Where chemicals

are introduced into the system, the potablewater supply

shall be protected against backflow by a reduced pressure

principle backflow preventer.

The height for the valve above the system or sprinkler head is not given in the IRC. I guess it defaults to the manufacturer?

The IRC defaults to the "applicable standard" at the right column of Table 2902.3. The UPC is more helpful. Its analogous table is 6-2. The far right column in that table gives specific heights for each type of backflow prevention device. For atmospheric vacuum breakers and spill-resistant pressure-type vacuum breakers, the distance is 6". For Pressure vacuum breakers, the distance is 12".

- Jim Katen, Oregon

I knew I had seen 6" somewhere! I guess to be on the safe side just say 12" and be done with it.

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For anyone that might be interested: The outstanding document Charlie put up, points out that the double check-valve system backflow preventer is no longer permitted on residential lawn irrigation systems.

I had the good fortune of speaking with an irrigation guy today, and learned why those units are no longer approved. The reason is actually a pretty big deal to HIs, so getting familiar with that unit might be prudent. I see them often.

The double check-valve system worked fine, but when it fails, there is no visible or apparent sign of failure. It simply becomes an instant undetectable cross-connection! And, since it was designed to permit the introduction of chemicals to the sprinkler system, this can be a REAL problem.

The newer reduced pressure system, has a relief valve that begins to dribble or flow when the unit fails. (brief minor intermittent flow is normal, but constant dribble or flow indicates failure).

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For anyone that might be interested: The outstanding document Charlie put up, points out that the double check-valve system backflow preventer is no longer permitted on residential lawn irrigation systems.

I had the good fortune of speaking with an irrigation guy today, and learned why those units are no longer approved. The reason is actually a pretty big deal to HIs, so getting familiar with that unit might be prudent. I see them often.

The double check-valve system worked fine, but when it fails, there is no visible or apparent sign of failure. It simply becomes an instant undetectable cross-connection! And, since it was designed to permit the introduction of chemicals to the sprinkler system, this can be a REAL problem.

The newer reduced pressure system, has a relief valve that begins to dribble or flow when the unit fails. (brief minor intermittent flow is normal, but constant dribble or flow indicates failure).

And for the Oregon guys, double check backflow valves are still very much legal here.

- Jim Katen, Oregon

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