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Before people say, "Ask the AHJ," I am him; he is me.
I have an applicant who has combined plots of land with a mid-rise and some detached townhouses. A shared fire line supplies the two structures, but only the mid-rise FACP monitors the supply tamper. The townhouse FACP will not know if the water is off (except for the tampers at the risers within the townhouse). The buildings are owned by the same ownership. They are arguing they are technically meeting IBC 2015 903.4 "Valves controlling the water supply for automatic sprinkler systems, pumps, tanks, water levels, and temperatures, critical air pressures, and waterflow switches on all sprinkler systems shall be electrically supervised by a listed fire alarm control unit." It is being monitored, but the fire marshal and I are of the opinion this doesn't provide monitoring for the townhouse and does not meet the intent of the code. Does anyone have any thoughts on whether a shared line can be monitored by only one building that it serves? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
6 Comments
My jurisdiction (I am the AHJ) has had several buildings built with private hydrants supplying the sprinkler system where the main comes into the building, through the RPZ, feeds the sprinkler system/standpipes, and leaves the building and feeds the hydrant(s).  This has always seemed counterintuitive to me, at best. I feel we are "robbing Peter to pay Paul" and have wondered if this arrangement will adequately supply the sprinkler system when we (FD) pull water from the hydrant and pump it back into the FDC.
Per our state law, private hydrants have to be "protected" with a backflow. Is this configuration code compliant, and if not, what is a solution? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe In an area subject to freezing, we have a remote FDC that supplies a riser room at the same level. The feed is through underground pipe.
Is the base of the FDC required to have an automatic drain similar to what's at the base of dry barrel fire hydrants? If not, how are these FDC's typically drained after use? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is there any particular drainage pipe requirements needed for an FDC that makes a U-loop underground?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a fitting (a 90-degree elbow) from a fire ductile iron water line be under the footing, which turns the pipe up into the Fire Pump room?
In other words, the pipe feed comes from a water tank underground, then turns up with a 90 under the building footing and the pipes through the footing. Is this acceptable? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a bunch of new houses going in. Some are along an existing street, and some are around a newly formed cul-de-sac.
How do I determine the number of hydrants, how far apart they are, and the maximum distance to any of the homes? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe If I have a fire tap that services multiple buildings, is it required to have a service valve outside the building on each line?
Does each building need to be capable of being isolated in case of service needs without interrupting others? As it is, if one building needs work done to the #1 valve on the backflow then the other buildings will have to lose water during repair. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe MeyerFire has a great thrust block calculator that appears to match NFPA 13’s annex/appendix exactly. https://www.meyerfire.com/blog/a-new-thrust-block-calculator-part-i How can the thrust block volume fit within the dimensions of the thrust block? The default entries, for example, give a thrust block volume of 57.8 ft³ (NFPA 13 Equation A.6.6.1c), a base height of 2.2 ft, and a base width of 4.27 ft. This meets the bearing area required by the equations. NFPA 13, Figure A.6.6.1(b) gives the angle between the base of the thrust block and the pipe as 45°. This makes the thrust block a pyramid shape but ends with a pipe instead of coming to a tip. The Figure shows both vertical and horizontal angles as 45°, but that wouldn’t work unless the height and width are equal. If 45° is the minimum angle, then the width of 4.27 ft would control the distance from the base of the pyramid to the pipe. If each side has a 45° angle, this distance would be half the width or 2.135 ft. These dimensions can be used with the pyramid volume formula to give another method to check the thrust block volume. The pyramid formula is V = L*W*H/3, which gives a volume of 6.7 ft³. This is very different from the NFPA equation result. Even if the thrust block was poured as a cube, its volume would be V = L*W*H, which is 20 ft³ -- still much smaller than the NFPA value. – I am counting the tip of the pyramid, which is part of the pipe, not the thrust block. It would be more accurate to exclude the tip, lowering the required volume slightly, but it would be harder to calculate. If the pyramid were 57.8 ft³ with a bearing area of 2.2 ft by 4.27 ft, then it would need a distance from the pipe of 18 feet. I think there is something wrong with Equation A.6.6.1c in NFPA 13. It doesn’t make sense that it cancels the thrust force with the weight of the fill material. If you could use some incredibly dense fill material (pretend fantasy fill that is 8670 lb/ft³), then the thrust block volume would be 1 ft³ by that formula, but how is that small thrust block volume going to transfer the thrust forces onto a large enough soil surface?  The weight of the thrust block material should not be related to calculating the volume of fill material required.
Another issue I see with the equation is that it is suddenly using T = P*A*sin(theta) while all previous formulas were using T = P*A*sin(theta/2). Why did the angle change for this formula? Thanks in advance for any insight you could shed on the difference in volume versus shape with the NFPA formulas. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a scenario where the fire riser will be installed after the building is completed. If the pipe is located below the pedestrian walkway area, is this required to comply with NFPA 13, 2022, (6.4.2.2.2 In locations where freezing is not a factor, the depth of cover shall not be less than 30 in. (750 mm) below grade to prevent mechanical damage. [24:10.4.2.2.2])? See the attached sketch. If yes, what is the possible solution? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Can a 4" pump with 4"-6" discharge fitting be used on a private 10" combination line (fire suppression and hydrants)?
NFPA 24 Section 13.1 states that no line less than 6" shall service a hydrant. But does the fact that NFPA 20 Section 4.16 allows the 4"-6" discharge fitting as part of the pump assembly overrule this? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Hi all, what is the maximum length of the connection from the hydrant to the fire water main?
NFPA 24 mentions that the minimum size is 6" but couldn't find anything related to the pipe length. Thanks Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Typically when I work on campus/multi-building systems, I am using a single underground main and splitting off to each building. Since you don't have to consider a multiple building fire problem, we have typically worked on the hydraulically most-remote building for underground sizing and use wall PIVs to offer individual building shutoffs, with FDCs on the individual buildings.
I'm getting challenged on "what allows this in code?" It's mostly a question of - where is the limit on how long a loop can be? I'm looking at this from a sprinkler design perspective and whether each individual building's sprinkler system is able to perform hydraulically. Is the limit for the length/layout/sizing of a campus underground loop simply the more demanding of Fire Flow or sprinkler system feeds? Is there a code basis for this? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe According to NFPA 13 2022 Section 16.9.8.2 it is to our discretion what we consider a location " where they are not subject to mechanical damage?
When installing a Post Indicator Valve, what do you consider "not subject to mechanical damage?" Where is the line drawn, so to speak? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Had a review comment come back and needed to clarify. I have a 14-inch city main with an 8-inch tap to a backflow in a pit. It then runs to four hydrants, and then turns into the building supplying a fire pump. The flow test at the hydrant near the tap (#1 on image below) was 49 psi static, 47 psi residual at 920 gpm. The flow test at a hydrant nearest the building (#2 on image below) was 49 psi static, 39 psi residual at 750 gpm.  The 95 psi @ 1,500 gpm pump in the building is running the underground dry. The plot curve shows 20 psi at 2,100 gpm, however the pump rep said he barely got 500 gpm at 9 pitot and had to shut it down as the gauges went below 20 psi and air was starting to come out of the 2-1/2" hose valves.
This is a mystery to us - we have five different flow tests all ranging from 750 gpm to 1,060 gpm at 40-32 psi residual. Why would the pump be pulling the underground so low? They checked all the valves and rebuilt the backflow in the pit. Water meter is good as well (per the utility department). Looking for suggestions. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a floating dock standpipe with hose valves in the ocean be ran with PVC pipe?
NFPA 307 doesn’t go into detail about materials used but reverts back to NFPA 20, 22 and 24. This is in Florida. The AHJ wants it full of water so I have to issues, it’s too heavy to mount on the side of the dock, it’s not very big and it will be in the water or very close with high tide, so corrosion is inevitable. Is there anything stating Schedule 40 or 80 PVC is listed or acceptable for such use? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a private water main feeding a combined domestic and NFPA 13 system that was specified as C900. They installed SDR21 (6") instead.
They are using the argument that this 200 psi rated pipe will not be subject to the fire system pressure and therefore is ok. I cannot find where this is listed for fire service mains. Any direction? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Would it be possible to replace a Kennedy K-10 dry barrel fire hydrant with a wet barrel fire hydrant if the main valve of the K-10 was left open, and a wet barrel hydrant was then bolted to the standpipe base?
We're in southern California, so we commonly have wet barrel hydrants in the area. Replacing with a wet barrel means we wouldn't have to excavate. The main reason I see is that the drain holes would be left open if the dry barrel main valve is removed. We have been unable to find new main valves for Kennedy K-10 hydrants. Your comments would be greatly appreciated. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Last week someone asked a great question about the limits of where NFPA 20 starts and stops.
In a similar vein, what are the limits of where NFPA 22 and NFPA 24 start and stop for a typical system with a water storage tank, fire pump and private mains? We had a question at work yesterday as to whether NFPA 24 or NFPA 22 applies to pipe before a water storage tank. It'd be helpful for us to understand these limitations in addition to the conversation last week. Thanks in advance! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe In the NFPA series of standards, is there a requirement for a water line supplying private fire hydrants to have backflow protection?
I am working on a project where the fire marshal is requiring double check detector assemblies to be installed on six private fire hydrants. The line serving the hydrants has no other connections to it. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am running 8” and 4” water storage tank fill and suction lines above ground in an exterior utility yard. Is lateral and longitudinal bracing required for aboveground piping supported on pipe stands located outside of a building, in an exterior utility yard? Due to underground conflicts with spread footing foundations the underground piping has to be routed above ground to the final location and connection points on the tank. The pipes are supported by 1’-6” non adjustable pipe stands attached to slab on grade. This project is located in a seismic zone and the seismic force factor does not exceed 0.5Wᵖ and I am using ACI 355.2 qualified anchors as required by NFPA 13 2016 Edition. Sections 9.3.8, A9.3.8, 9.3.8.1, and 9.3.8.2. The pipe stands I am using are following the NFPA 13 2016 Edition prescriptive method detailed in sections 9.2.6.3.2, 9.2.6.4.2, 9.2.6.4.4.1, and 9.2.6.4.5.1, I’ve also attached a detail for clarification. Thanks in advance!  Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
If I have a PIV installed, is it required to be tied into a fire sprinkler system?
I work at a campus style facility with a fire water supply loop for fire sprinklers. We have a couple of buildings that do not have a fire sprinkler system, however, there is a PIV outside the buildings that are in the closed position. I am assuming they were installed for "future use" assuming a fire sprinkler system gets installed. Is there an NFPA code reference that requires the PIVs to be "in service" or used for their intended purpose, or are we code compliant with them being "for future use"? I do have a concern with responding fire units incorrectly assuming that there is a fire sprinkler system in these buildings due to the PIVs being installed. What are your thoughts? Thanks! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Are you required by NFPA 24 to enter a building underneath the foundation, or can you enter a building with the the fire service main from the side of the building?
Many are under the impression that due to the fact all illustrations in NFPA 24 show the fire main entering under the building, footing/foundation, that this suggests that it is a requirement. Please can someone shed some light on this? Regards. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm working with a city inspector who is adamant that we add a second non-rising stem valve (NRS) in the fire sprinkler service main just before the building. The first valve being in the street at the live-tap location with the roadway box.
Is a valve required on the service main before the building? The requested location would place the valve under the sidewalk, accessible by T-handle wrench only, prohibiting reliable supervision of any kind. I can't seem to find any language in NFPA 24 that I can use to argue against the second unsupervised valve. I don't see any value in the position the inspector has taken and requested a copy of the city ordinance requiring the additional valve. Installing the second valve wouldn't be a huge deal but certainly seems like an unnecessary opportunity for an unsupervised valve to get closed or fail. I would like to hear what others in this community think and if anyone has something to offer. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can HDPE ISO 4427, PE100 SDR 9 PE be used for underground water service pipe (dedicated for fire water), even though it carries no FM Approval?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have question regarding fire pump capacity.
In my situation the water department is requiring a city tap size to be 2 pipe sizes larger than the fire protection backflow preventer. In my project, I was using a 4" backflow and 400 gpm fire pump so my underground/city tap would be required to be at least 6 inches. The AHJ is requiring me to increase the area size in one of my remote areas. So, my sprinkler demand now becomes 582 gpm. To avoid having to use a 500gpm fire pump (with a minimum suction size of 6-inch) and increase the underground to 8-inch, could I still use the 400 gpm fire pump to supply the 582 gpm demand? This comes out to about 145% of the pumps rated capacity. I have never come close to the 150% mark before and just want to see what others think. If the underground size wasn't required to be 2 inches larger I wouldn't even think about it and go with the 500 gpm pump. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
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