Forward flow testing of RP's on Glycol Loops
Forward flow testing of RP's on Glycol Loops
(OP)
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
Dave





RE: Forward flow testing of RP's on Glycol Loops
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
RE: Forward flow testing of RP's on Glycol Loops
RE: Forward flow testing of RP's on Glycol Loops
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
RE: Forward flow testing of RP's on Glycol Loops
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.
RE: Forward flow testing of RP's on Glycol Loops
RE: Forward flow testing of RP's on Glycol Loops
RE: Forward flow testing of RP's on Glycol Loops
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
RE: Forward flow testing of RP's on Glycol Loops
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.
RE: Forward flow testing of RP's on Glycol Loops
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
RE: Forward flow testing of RP's on Glycol Loops
My question what do we do in this case?
RE: Forward flow testing of RP's on Glycol Loops
Dave
RE: Forward flow testing of RP's on Glycol Loops
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.
RE: Forward flow testing of RP's on Glycol Loops
Regards
Dave
RE: Forward flow testing of RP's on Glycol Loops
Start there for now
RE: Forward flow testing of RP's on Glycol Loops
Regards
Dave
RE: Forward flow testing of RP's on Glycol Loops
RE: Forward flow testing of RP's on Glycol Loops
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
www.mfpdesign.com
RE: Forward flow testing of RP's on Glycol Loops
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.
RE: Forward flow testing of RP's on Glycol Loops
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
RE: Forward flow testing of RP's on Glycol Loops
Just to through it out there as food for thought,and I haven't dealt with AF systems in a while, but might it be an option on some of these buildings with alot of AF systems, to swap out the big DDCA at the supply for a RPZ and change the existing small AF RPZs for swing checks with 3/32 orifice. The cost might be offset in certain cases with not needing to retro fit multiple test headers and reduce testing costs in the future. Obviously actual valve takeouts and availability need to be verified.
RE: Forward flow testing of RP's on Glycol Loops
Regards
Dave
RE: Forward flow testing of RP's on Glycol Loops
Just to mention as a reminder, RPZs typically have more friction loss, so that needs to be concidered. Though hopefully with the improved hydraulic design of the newer models, along with the reduced takeouts, may still remain an option for these new buildings.
Accomadation for RPZ discharge would also have to be concidered, etc.
100 buildings! Nice work if you can get it:). Good luck!