Backflow preventors 4

[okieduck]

Hi everyone!
Our city is researching the issue of backflow preventors and double detector checks. The problem is, we have researched EPA, AWWA, and other agencies for standard specifications and can not find any. Basically it is up to the local authorities to determine what shall be used. If anyone has experience in this area, I would appreciate some guidance. Currently we use 4"-10" DDC and we are looking to reduce the cost of installation.
Thanks for your time!
Joy

 

[hydrae]

One method that I have seen for the consistant fire water user, is that if there is consumption on the bypass meter, The customer gets a letter, expaining that if the use is not stopped in six months, the fire system will be considered standard use, which will require the installation of a full size meter with the system development charges, for which the customer will be billed, many tens of thousands of dollars.
This method requires "policy makers" direction though
Hydrae

 

[KRSServices]

Okieduck,

I think my wires are crossed on this one, and therefore a little confused. Initially you were referring to a double detector check, and normally for larger services, the installation (at least up here) is provided with a bypass line so that the valve can be serviced without interuption of service.

The service line is metered elsewhere. My questions concerning the bypass and therefore the comment regarding unauthorized use pertains to how the bypass is termed and used. In your case, is the term "bypass" the fire line into the building? If so, then how is it that the bypass line is metered?

You mentioned the double check requires a minimum of 3 gal/min. This sounds like a compound system (high vs. low flow). If the water through the bypass and the big check valve is metered, how then is it possible to be unauthorized?

To me, unauthorized use is the bypassing of the meter with a water line or the installation of a secondary water service, unknown to the Owner of the Utility. Depending on the size and use of the building, the 3 gal/min through the bypass may or may not be a leak, but if it is a known quantity and being paid for by the building owner, why is everyone so excited? Unless of course, water conservation is the prime goal in the entire exercise. Is it possible to elaborate further, the comments thus far have sparked my interest and now I'm the Curious George.

KRS Services

http://www.krs-services.com

 

[okieduck]

KRS,
Sorry for confusion. Basically, there is no other meter on the fire lines except the bypass meter on the DCD. The guys go out and see a use on the bypass meter, record and go on. What the big deal is the amount of water that has been detected. Like 200,000 gallons. Thats too large to be a leak. And its not just this business that has a large reading. If these are all leaks, we have some serious work ahead of us.
It is a high/low flow device as suspected. The bypass meter is required by USC to carry a minimun flow of 3 gal/min, and after that, the check valves open in the main assembly. The manufacturer states that flow ceases through the bypass after approximately 8-10 gal/min.
Hope I cleared your confusion, if not, let me know, cuz it also helps my communication skills.

 

[KRSServices]

Okie,

Thank you for your reply, while it did answer some of my questions, a few more have been raised. The 200,000 gallon usage, is it daily flow or monthly through the bypass meter? What kind of business is it? Is this an office building or tower, housing many offices? A laundromat? A plastics or fiberglas manufacturer? What is the daily flow through the main assembly, in other words, how often do the check valves open?

Depending on what the 200,000 gal. represents and the type of building, I am not thinking that the figure may not be too alarming at all. Can you email me with some specifics and is possible, the totalized meter readings for the building for a specified period?

I am still a little uncertain as to what you originally termed as unauthorized use.

KRS Services

http://www.krs-services.com

 

[okieduck]

KRS,
Well, maybe "unauthorized" use is a little hasty. I dont know the daily use, because the DCD is the only meter on the system. We have put in for a daily logger. This business is a hospital, which is even scarier. But I have ran some numbers, and over a 6 month period, which is the length of study so far, those numbers could indicate a major leak.
However, there have been no reports of drop in pressure or moldy walls or anything.
Anyway, that issue is being argued by higher than me, so I quit for now. Thanks for your interest!

 

[KRSServices]

Okie,

LOL, sorry to see that you are bailing on this issue. Schools and hospitals are traditionally one of the highest users on a system. Considering that the meter is not situated on the only water source, nor a compound meter, I would venture an experienced guess that the water flows are likely quite normal. Hospitals have an incredible amount of different fixtures and it is likely that those flows are not abnormal, rather, they are likely a typical flow. This of course can be evaluated and calibrated by other observations to substantiate whether there is a leak present.



KRS Services

http://www.krs-services.com