Should the FDC (shown below) be connected where it is shown on the proposed riser schematic?
It is my opinion that the right portion of the image below does not show proper connection of the FDC to the risers.
Is this correct?
It appears that the FDC if used, would send pressure back against the RPZ and diminish fire flow to the risers in use.
The pressure at the street is 80 psi. Water coming in at the FDC may be 150 psi. Note the connection to a fire hydrant.
Should the FDC connect directly to the dry and wet pipe fire sprinkler risers as required by code or is the proposed riser schematic acceptable?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
5/16/2023 07:33:14 am
NFPA 13, 2022 - 220.127.116.11
5/16/2023 08:06:38 am
I agree with Dan. I don't haver an issue with the FDC, but the addition of the CV where Dan indicated can save some headaches down the road.
5/16/2023 08:16:16 am
The local FD will connect into the hydrant to support the FDC. With no check valve, water will circulate back through the bottom of the riser, and back to the hydrant, causing the FD to be pumping back to itself thus limiting the amount of water going into the risers.
5/16/2023 08:27:16 am
I agree with Dean. You also have to understand that if the system is shut down at the backflow, there would be no water to the hydrant to supply the FDC. This arrangement should have the hydrant off the city water underground somewhere before the backflow.
5/16/2023 09:25:23 am
The arrangement looks correct minus the additional check valve mentioned above.
5/16/2023 09:29:34 am
I have no issue where the FDC is located. I do have an issue with the way the fire hydrant is piped downstream of the RPZ. When the fire hydrant is connected to the FDC, there will be a circulating loop, which will prevent water from getting to the sprinklers or the hose valves.
5/16/2023 09:42:40 am
I agree with Glenn, that's a bad idea leaving the hydrant connection at the riser design, poor engineering
5/16/2023 01:50:07 pm
I concur with almost all the statements 100%. Bad arrangement, that can be made less bad by adding the check valve mentioned. But, it's still a bad arrangement.
5/17/2023 07:13:18 am
In looking at this arrangement, the only possible reason for installing a hydrant as shown would be to facilitate full forward flow testing of the backflow preventer. It's a confusing and ineffective location for fire protection, preventing the FDC and hydrant from accomplishing their sole reason for being: support or reinforcement of the fire sprinkler system under maintenance or emergency situations.
5/17/2023 01:24:24 pm
We as an AHJ do not permit the fire hydrant to be connected as shown. Other than the street valve(s) they have to be live at all times.
5/17/2023 02:26:46 pm
Yeah, seems like it just needs a check between the hydrant feed and the riser,
5/22/2023 06:14:47 pm
In Illinois (I believe a health department requirement) any private hydrant must be "protected" by the backflow preventer and thus would have it located after the RPZ. I have never been a fan of this...unless there is a bypass that can be opened while maintenance is being performed on the RPZ.
Leave a Reply.
Subscribe and learn something new each day:
Top May 2023 Contributors
Get 100 Days of Free Sample Questions right to you!
PE PREP SERIES