Forward-Flow From Hose Valves Over FDC?

10/11/2021

So the issue of "forward-flow testing" of the backflow preventers has come up a lot as of late, at least here in Massachusetts. More and more design drawings are calling for "provisions" to forward-flow test the backflow preventer. I've seen multiple ways of doing this and I'm curious as to which method is best.

One method I see is adding a bypass around the FDC check with a normally-closed butterfly valve in it. This allows you to open the butterfly valve when you want to test the backflow preventer and flush through the FDC piping.

The other method I see is to extend the manifold and install a couple hose valves to use in testing.

My personal opinion is that if you have the ability to run the hoses outside, use the second method. The reason for this is that if each zone has a control valve, you can shut off the sprinkler system while flushing and not introduce any of the debris in the underground into your system. By doing it the other way with the bypass, you have to mess with the FDC, and if the FDC is fed from anywhere on the system other than the end of the manifold, you can introduce debris into your system.

Is this a better approach?

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13 Comments

Alex

10/11/2021 06:26:17 am

Hi Anonymous,

There is nothing in NFPA 14 that states one method is better than another. From my own opinion, I agree that minimizing the amount of water running through the system is best. I’ve added a hose valve to the end of my manifold multiple times to provide a means to forward-flow the backflow preventer.

I’m curious to see what others have to say.

Thanks,
Alex

Craig Hanson

10/11/2021 08:11:21 am

As a former fitter who is now an Inspector and plans reviewer. I will say the easiest way to do the forward flow test (its only done every 5 years) is to take a pup piece of piping the same size as the check valve and swap them out and test through the FDC. you will also have to take the FDC siamese off but that's no problem. This is a lot better than dragging hoses up a stairwell and connecting to the combo standpipe hose bibs and a lot less messy with no tripping hazards for residents.

Jessica Lutz

10/11/2021 10:16:58 am

This is a great solution, as long as the FDC is easily removeable.
Many contractors prefer FDCs with snoots in walls, and/or internal clappers.

chad

10/12/2021 07:37:12 am

The issue with that is, it requires the tester to reverse the check valve when he is done. As me how I know this gets left that way.... Laziness, mistakes etc. get in the way of this being fool proof. The bypass valve around the check with a tampered valve, at least its supervised.

Randy Kimbro

10/12/2021 03:03:34 pm

As an AHJ, the forward flow test is required ANNUALLY and usually done as part of the annual sprinkler inspection (NFPA 25 (2017) 13.7.2. MeyerFire had a great article about this in 2018:
https://www.meyerfire.com/blog/solutions-for-the-overlooked-forward-flow-test

Starting with NFPA 13 (2019) 16.14.5.1.1 the ability to perform the forward flow test must be hard plumbed; "serviceable without requiring the owner to modify the system to perform the test.

The FDC hydrostatic test is done every 5 years. NFPA 25 (2017) 6.3.2.

Jack

10/11/2021 08:46:12 am

In the 80 s , when you bought a bfp, they included hose valves to test it.
Due to competitive pricing, and the “ rules “ not forcing to forward flow them, the inclusion of the valve(s) seemed to drop.

CJ Bonczyk

10/11/2021 09:04:09 am

Personally if possible I like to eliminate the amount of wall penetrations as much as possible. I will make the main drain large enough to accept full flow of the backflow and tie the flushing connection into that. Then any ancillary drains (fdc ball drip, main drain, inspectors test, etc.) into a large drain manifold and make a single penetration. Thus you would have possibly only a FDC wall penetration and drain penetration. If the backflow flushing connection required is too big I just try to create a multi hose valve test connection on the manifold.

Jesse

10/11/2021 10:12:57 am

I once had the CEO of a Fortune 500 tell me, "it doesn't matter who pays the green fees, just that the green fees get paid".

In my professional life, I took that to mean that there are numerous ways to achieve the outcome needed, and how we get there needs doesn't need to be the same way for every situation.

Several AHJs in my area are hitting this as well. And I think the solution is project dependent. All of these are good options.

Dave

10/11/2021 10:48:23 am

For comparison, whether the backflow is inside the building or out in the yard, we spec incorporating full forward-flow test valves as part of the riser manifold assembly, starting with a normally closed butterfly w/tamper switch* , THEN to the required quantity of 2-1/2" hose valves, penetrating the wall. Like CJ, I'm not a big fan of additional wall penetrations, but this is our preference. If this does not result in the hose valves penetrating safely into a service yard, if theft might be an issue, or in certain education or healthcare situations, I will keep the hose valves inside the riser room with the hose discharges directed towards the riser room door to the exterior and hopefully they bring intact hoses. Where theft might be an issue, I've seen 2-1/2" grooved caps installed through the wall with loose grooved hose valves supplied in the riser room. I've also seen low-bid sub just install a capped shaped nipple on the manifold and say there is your "means" - Not good.
Despite all this effort, unfortunately my local AHJ's still haven't been enforcing this testing requirement.

* For proper tamper operation it must be specifically a normally-closed model such as the Vic 707C, Tyco BFV-300C (black-handle), Reliable N.C. BFG-300, etc., and make sure the fitter knows the difference.

Mike

10/11/2021 10:57:49 am

I've designed downstream test manifolds similar to fire pump test headers.

I think what's important is the estimator needs to preplan this with the designers and incorporate that into the bid to prevent arguments if they win the job.

Bruce Seiler

10/11/2021 01:03:22 pm

We have done many of the comments above. I personally do no like utilizing the FDC. As mentioned above, in order to gain the full flow from the outlet, you need to removed the FDC unless it is a Storz Connection. I like the idea of connecting the test discharge to the a drain existing the building. We do this as part of our standpipe system testing where we upsize the drain and utilize that to discharge the water outside.

Question. What type of equipment is everyone using to perform this test?

Anonymous

10/12/2021 05:01:55 pm

"Question. What type of equipment is everyone using to perform this test?"

I'm curious, too, because in my experience, enforcement of this requirement has been rare. However, I have seen Hose Monsters used to measure flow, it seems most contractors I know have them. I've seen specs that require in the process, measuring and recording pressures upstream and downstream of the backflow to verify the backflow pressure loss, but correct me if I am wrong, this was never NFPA's intent; system demand and exercising the backflow being the primary goal.

David

10/13/2021 05:22:51 pm

Most of the time I see the main drain sized to accommodate the system demand, or an FDC bypass is used (only one outlets flows because of clapper though). I use a pitot gauge to measure the flow.

The problem I come across is that many of the fitters in my area don't cary the equipment (hoses, hose monsters, etc) to conduct the test during system acceptance. Can really ruin the landscaping if it hasn't been planned for.

Forward-Flow From Hose Valves Over FDC?

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