PVC Allowed for Remote Underground FDC Feed?

5/15/2020

Have a project which has a remote fire department connection outside of the main building. The fire department connection has its own dedicated feed that goes from the remote FDC, underground, up into the building, where it connects to the fire sprinkler riser downstream of the backflow preventer.

The check valve for this line is required to be inside the building, so the main between the FDC and check valve in the building is intended to be dry.

NFPA 24 (if that applies) allows PVC for underground water service in its table of permitted pipe types.

NFPA 13 specifically states that galvanized steel is permitted to be used between the FDC and the check valve serving the FDC. I can't see where NFPA 13 would mandate pipe types for this arrangement.

Is this underground FDC feed allowed to be PVC?

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9 Comments

Wes

5/15/2020 09:59:40 am

A few references:
- NFPA 24 allows water service pipe to be PVC, but has no mention of different pipe types for typically dry mains (NFPA 24-2019 Table 10.1.1.1).
- NFPA 13 permits this FDC feed to be galvanized steel, but does not mandate any pipe type for this application (NFPA 13-2019 10.1.1.3). Commentary states this approach is possible, but coating and wrapping would be necessary.
- NFPA 13 permits unprotected cast-iron or ductile-iron where jointed with gasketed joint for air service underground (NFPA 13-2019 6.1.1.4.2). This pipe is not pressurized, however, as a dry system routed underground would be.
- Cutsheets for AWWA C900 PVC pipe don't appear to exclude normally-dry applications.

Casey Milhorn

5/15/2020 12:47:28 pm

Lots of great comments. One additional thing to watch for is the class of C900 pipe. Years ago DR-18 was listed to 150 psi if I remember correctly, which ruled it out for use on an FDC line that may be pressurized over that. Now DR-18 is listed for 235 psi, and DR-14 is listed for 315 psi (from memory, did not verify the pressures). So in most applications DR-14 and DR-18 should be acceptable as long as the application isn't in a fire district where there SOP require pressures over 235 psi. You definitely probably want to avoid DR-21 or 25.

Mike

5/15/2020 10:30:27 am

Why is the check valve required in the building?

If I remember correctly, the FDC check needs to be replaced verified that it opens every 5 years. That's going to be a mess if it's inside the building.

No mention of freezing conditions in OP. I'm in SoCal so we don't have freezing conditions. I don't know how East Coasters do it.

Thanks for the question.

Wes

5/15/2020 10:32:49 am

The AHJ is requiring it inside the building - I'm guessing so that it is accessible for testing and not buried below grade.

Freezing is not a concern for this project. It's in an area that could freeze, but freezing is not a specific concern for this pipe.

Shane

5/15/2020 12:52:51 pm

I had the same question on the check valve location in reference to the FDC. I have always put the check valve close to the yard FDC to keep it full of water to prevent all the air being pushing into a system during a fire. Although, I have recently be corrected in rather rude response that I should know my code and to look up, NFPA 14 6.4.2: Locate the check valve as near as practicable to the point at where it joins the system. I understand keeping the pipe dry in freezing locations, but I am in Florida.

Rob

5/15/2020 11:08:46 am

On a lot of projects, the piping for the fireline and remote FDC line are on the Civil Drawings and will call out the materials based on local requirements. In a lot of jurisdictions what materials and installation practices are dictated by the local municipalities public engineering department or water department. Usually what I have seen even in a dry remote FDC line is either C900 or ductile iron pipe, usually with a ductile spool (flanged) to come up above grade. Hope that helps.

Jonathan Joseph

5/15/2020 11:24:00 am

I don't see a problem with the pipe material as long as you restrain it well and make sure it is at least 1 foot below the frost line.

It will be up to your AHJ but my main worry about non pressurized FDC is that pedestrians could throw trash in the FDC.

Make sure that AHJ is ok with having locking FDC plugs

Richard Mercer

5/15/2020 12:27:39 pm

You did not mention the version of NFPA 13 the Jurisdiction references. the 2019 NFPA 13 Hand Book had an FAQ for table 6.1.1.1.

"The use of plastic pipe, including polyvinyl chloride (PVC), polyethylene (PE), and oriented polyvinyl chloride (PVCO), are now included in Table 6.1.1.1 for use in underground systems, provided the piping is manufactured in accordance with the referenced AWWA standards. Listings are available for PVC and PVCO pipe and couplings for underground fire service."

Wes

5/15/2020 12:28:57 pm

Thanks Richard - it is the 2019 Edition. I was just curious if it being typically dry changes the material requirements at all.

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