Forward flow testing of RP's on Glycol Loops

[ContractorDave]

I may have asked this question before ... I know that NFPA hasn't replied to me on this yet: Is forward flow testing required on the glycol RP?

Dave

 

[cdafd]

GOOD question

I guess 1st question if you are talking about a small part of a larger system that the anti freeze is tapped off of, is how much floow do you need??

Can it be achieved by a drain or inspector test, which it looks like it should.

Seems 13 means all backflows on a system

 

[cdafd]

other question is is the device testable, and what kind of test can be done on it??????

 

[ContractorDave]

Generally speaking, a glycol loop is a part of a larger system. Regardless, that's the situation I am asking about. I have never seen an RP on a glycol loop with a connection installed on it for the purpose of a forward flow test. You would not want to use the drain connection because you would be wasting glycol. I suppose if a check valve were installed after the RP with a tee in between it could be done.

My specific situation involves a facility with 4 separate glycol loops of varying sizes. There is one 8" DCVA on the supply which we flow test at a wall hydrant. There is no provision other than the loop drains to forward flow the anti-freeze systems. The amount of time involved would be significant, never mind the costs associated with replacing glycol.

Dave

 

[cdafd]

well first problem is I do not think forward testing came into play in 13 till 2002

then any system prior to that would more than likely not have the setup to do the test


also, some ahj's are not requireing the forward flow testing for a few reasons.

 

[cdafd]

I guess you could shot a proposal to the owner to install a means to flow test.

 

[NJ1]

In my opinion if a forward flow test is required but the system has a Glycol loop the only way is to proposed to the owner to recycle the antifreeze while the test is being performed. After completing the test you must recharge the system with the glycol solution. All this must be done while weather permitting.

 

[ContractorDave]

""In my opinion if a forward flow test is required""

Well that's just it. IF it is. Is it? I have posed the question to both the NFPA 25 and 13 committees and neither have chosen to respond yet, where in the past with other issues I have inquired about they have always been quite expedient in their replies.

Dave

 

[NJ1]

I think I have the answer for this.
NFPA 25-2002 Edition section 12.6.2.1
All backflow preventers installed in fire protection systems SHALL be tested annually in in accordance with following:
1) A forward flow test shall be conducted etc..........
2) A backflow performance test , as required by AHJ, SHALL be conducted etc..........

No where in the standard has an exception to GLYCOL loops. Like i said before it must be schedule during weather permitting so that glycol can be recycle.

 

[ContractorDave]

If you finish the sentence, you see the problem NJ;
25, 2008, 13.6.2.1:
(1) A forward flow rate shall be conducted at the designed flow rate....

When have you ever seen a data card on a glycol loop telling you it's designed flow rate unless perchance it happens to be one of the calculated areas? You are certainly not going to flow a 2 1/2" RP at the system DFR if it's part of an 8" system.

Dave

 

[NJ1]

I am just going by the what the standard says. I have never seen no exeptions to the rule. I have never seen a data card on a glycol loop telling you it's designed flow rate however I would like to see th exeption on any NFPA 25 standard. Also I just reviwed the 9th Edition of Cross Connection manual which supersedes NFPA 25 and there is no exeption there neither.
My question what do we do in this case?

 

[ContractorDave]

As I mentioned NJ, I have asked for clarification from both NFPA 13 and 25 committees but they have chosen to remain silent on this issue. Perhaps this is an outstanding issue that they are still in the midst of dealing with?

Dave

 

[NJ1]

I dont know why you have to be so agressive with me. Like I said the standards dont have an exeption at all. Besides this whole conversation started because you said:
Is forward flow testing required on the glycol RP?
Untill I dont see an exeption or the committes says other wise then is required. I asked my Boss which is a PE and he stated the same as me. Untill you find somewhere in the standard an exeption then is required. Perhaps we should confirm with the Cross Connection Manual as I did and there is no exeption neither.

 

[ContractorDave]

My apologies NJ, but I'm not good with 'argument from authority' (ie I'm a such and such with this lovely pedigree so there!). I'd much rather hear a reasonable argument on the merits of a particular stance ... the pros and cons of a situation. That is how one learns something. Not because you read in some standard "it SHALL". I like to understand WHY it shall. I have questioned NFPA on many issues over the years. Sometimes their explanations or interpretations are concise and helpful - other times not so much. On this particular issue I have asked for direction from two separate committees and have received no response whatsoever. As usual I have also posted my question here. So far, nothing that has been said has convinced me that forward flow testing of the backflow preventer on glycol loops is intended. The wording of 13.6.2.1 (1) ..."where hydrants or inside hose streams are located downstream of the backflow preventer." and A13.6.2.1 ...A bypass around the check valve in the fire department connection..." appears to address a backflow preventer that is present at the system supply only, and not glycol loop devices.

Regards
Dave

 

[NJ1]

Why dont you try contacting the New England Water Works about the regulations or requirements stated on the Cross Connection Manual. I believe that this manual supersedes NFPA when it comes to backflow requirements.
Start there for now

 

[ContractorDave]

Thanks for that NJ. But I'm in Canada. Not only that, I'm in the Northwest Territories where we have yet to officially acknowledge the 21st century, let alone implement a cross connection protocol. The NFPA standards are more relevant to my situation.

Regards
Dave

 

[NJ1]

Wow. Sounds like some protocol issues has not being resolve by the Goverment in your area. Well Good Luck. Hopefully the NFPA can answer your questions. I am in the tri-state area where even the health department gets involved with Fire Protection. Crazy Huh?

 

[TravisMack]

Dave:

My gut feeling is that you need to test it. Assuming that this is for 40 gallons or less, the required design flow can't be that great and likely would get it out of a 1" aux drain.

This has brought up an interesting issue, and I am going to start showing the tee for testing and check valve downstream of the RPZ for the AF system to facilitate testing.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[Cidona]

I like the idea of the Tee and check valve after the RPZ.
If that was practical for this installation would seem you might have 2 courses of action.
(a) Get the system hydraulic information and see what flow is going through the RPZ. Test through the new test connection at that rate. Depending on how good the buildings systems's documentation and survability is this might be very esy or very hard, but if you're going to be retrofitting quite a bit of header piping the survey may not be that much more. Obviously depends on the site/contract conditions and documentation.
Option b would be less desireable because it does not comply to the letter of the Standard but may be something that Owner, AHJs, Insurance, etc may be okay with if option a is not feasible.
(b) Use the RPZ's Rated/Tested flow rate or call the valve manufacturer and see if they have any guidance on minimum testing.
I have heard alot of people having issues with some backflow preventers which I beleive is a large part of the motovation for requiring the forward flow testing. Would seem to make sense that the valve be exercised over the course of it's life.
I had not previously considered the requirement of the forward flow testing of the RPZ on the antifreeze but it would seem that in order to comply with 25, 2008, 13.6.2.1 the provisions should be provided for such test for new installations.
Haven't seen it myself but it would seem that's what would be involved in complying with the Standard.

 

[ContractorDave]

Travis

Jim Lake has responded from NFPA 25 with "It is the intent of the standard that all backflow prevention devices be tested for both forward flow and backflow.

However I believe that in the case of small preventers on antifreeze loops Paragraph 13.6.2.1.1 or 13.6.2.2 could be applied.

13.6.2.2 "Where connections do not permit a full flow test, tests shall be completed at the maximum flow possible."

My reply --------"Thank you for the reply. 13.6.2.1 (1) has the qualification “…where hydrants or inside hose stations are located downstream of the backflow preventer.”

I would submit that this precludes almost every backflow preventer on an antifreeze loop. Would this be a proper interpretation of this section?"---------

I was quite surprised to get a quick reply "I would agree, yes".

Now before anyone get's the idea I'm not wanting to test these devices let me clarify: Tom Wellan (AFSA) pointed out in a very good article (Back Flow Devices, Forward Flow Tests Oct 2006)that "the intent of 12.2.6.1 (now 13.2.5.1) is to exercise the back flow prevention device periodically since fire protection systems are relatively static." And I am in full agreement with this. The problem comes with this not quite hypothetical example: There is a tender out with 100 buildings, all with DCVA on the supply. There are 200 anti-freeze loops amongst them (Canada Northwest Territories remember?). The price of the tender is going to vary significantly depending upon how you have to deal with these 200 devices. Therefore I would like more direction or a better interpretation of 13.6.2 from NFPA.

And now I believe I have it.

Regards
Dave