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If I have an in-rack system that needs to be calculated with the ceiling system, does the ceiling system need to be positioned above the most demanding racking? This might result in neither individual component area used being the most demanding of their type. Or do I calculate the most demanding rack along with the most demanding ceiling? I drew a quick-and-dirty sketch of a warehouse with the most demanding rack in red, the most demanding ceiling area in green, and the water source in blue.  If the two areas are not lined up, this goes against the assumption that only one fire is happening in the building at a time. I'm thinking that the two need to be averaged over each other to come up with the most demanding single area, even if the most demanding ceiling or rack are not involved.
Thanks in advance for your input. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
11 Comments
In reviewing the top articles from 2024, I re-read #11 regarding forward flow. As an AHJ, this is something we have been focusing on for the last four years and have uncovered multiple water supply issues.
My question is related to NFPA 13 and the 2-1/2” hose valve that is required for every 250 gpm (950 L/min) of system demand. From the fire suppression side, we usually generalize that a 2-1/2” hose valve can only flow 250 gpm. However, in our forward flow testing and research, we have found that a 2-1/2” hose valve off a main riser can actually flow almost 600 gpm. So my question to the forum technical design experts is, if we are getting an adequate gpm flow for system demand from the pitot reading, do we really need to flow a hose valve for every 250gpm of system demand? In other words, if system demand is 450 gpm and we are getting that from a single 2-1/2” hose valve, is that accurate and acceptable? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe What is an acceptable means to inspect/supervise underground fire line isolation valves in a "roadway box?"
These are non-indicating and unsupervised valves on a fire line. They do not have a lockable lid and may be in a drive or roadway, i.e. subject to traffic. If you recommend a seal, please be descriptive of how that would be practical. NFPA 13 provides the following applicable guidance: 16.9.3.3.1 Valves on connections to water supplies, sectional control and isolation valves, and other valves in supply pipes to sprinklers and other fixed water-based fire suppression systems shall be supervised by one of the following methods: (4) Valves located within fenced enclosures under the control of the owner, sealed in the open position, and inspected weekly as part of an approved procedure. Thanks for your help. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am a project manager currently building a SCIF in Northern Virginia. I was told by the landlord that we couldn't use Schedule 80 PVC for di-electric breaks as they have had a PVC break causing millions of dollars of damage prior. We don't like wrapping/grounding the pipe.
Have you run into this? Do options exist, and what would you recommend to isolate through a SCIF? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe From my AHJ perspective and in regards to flexible drops and tenant improvements, where you typically don't receive hydraulic calcs, how are you then accounting for their equivalent lengths and friction loss?
I know some AHJ's require new calcs whenever these are being used period. I'm interested to see how others handle this. Thank you! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am working on a sprinkler system where the corridor has a wooden ceiling, as shown below. Upright sprinklers protect the space above the ceiling. I want to know whether the pendent sprinklers below the ceiling are also required? Is this an open grid ceiling under NFPA 13? The ceiling has the following characteristics: Bamboo ceiling panels with mesh void and solid wood frame with galvanized black metal rods as hangers for proper support, panels are to have a consistent panel size of 15 cm void between each panel and the wall and 30 cm void between the panels for the greenery to be hung. Can anyone help me in this case? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  I am hoping for some help here. I have a cold storage facility that has racks in it. Customer is adamant they do not want in-rack sprinklers. Building is 30-ft tall to the peak, storage is at 25-ft, racks are push back/drive in 29' deep with no longitudinal flue space. They are storing a Class I commodity.
Is there a ceiling-only design that's possible, for a dry system, for this? Or a direction for me to look into? It's not a conditioned space, just a big ice box. I would greatly appreciate any help or feed back, thanks. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Anyone know what temperature the sprinkler should be for a school's boiler room?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a small dry system of 196 total gallons installed in a small feed/grain storage warehouse at a Tractor Supply store. The dry valve is very close to the unheated storage area. They are using racks with commodity stored up to 15 ft high. This system is well under the 500 gallons for required water delivery time.
Is the Extra Hazard Inspectors test still required with two lines, two outlets on each line, or is a typical Inspectors test for Ordinary Hazard acceptable? I assume the Extra hazard arrangement is still required, but wanted some clarification. NFPA 13 Figure A.7.2.3.7 shows the manifold from four sprinklers and two branch lines. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe My area's adopted building code references NFPA 13, the 2016 Edition.
Should I even consider looking into the later versions of NFPA 13 (2019-present)? If there are major differences, how do we reconcile following only 2016 since the building code references it even though it may be outdated now? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Operationally, why would a fire department with a 1,500 gpm pump on a fire engine connect to a building FDC that has a 1,750 gpm pump?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Under NFPA 13, 2016, Miscellaneous and Low-Piled Storage in Table 13.2.1. A system designed for Ordinary Hazard Group 2 allows for 5-ft or less storage of Group A plastics, and in a separate section of the table allows for Class I- IV with a height of 12' or less.
Is it permissible to store the Group A on the floor up to 5-ft in height, with the Class I-IV above it on the racks provided the racks meet the requirements of this section? Section 5.6.1.2 on Mixed Commodities seems to address more the amount of what is being stored and not so much the arrangement. I can see both side of the argument, but I can't seem to find anything the answers my question definitively. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a project with deep concrete beams which are 24 inches deep, 4 inches wide, and located 6'-6" center to center.
Building is at least 20 years old. The original contractor, I think, treated the first beam like a wall and put a row of sprinklers on each side of it. The deflectors are 12 inches down. I'm assuming they then “skipped “ the next beam. At the third beam he put another double row. And then repeated the pattern. There are 4-inch deep lights in the center of each bay. They are sticking a layer of sheet rock on all sides and the ceiling. The sprinklers are 15 feet apart. It looks like the they are just protecting the bay on each side of the skipped beam with no sprinkler lines. The middle beam obstructs the coverage. This is a light hazard area with 9-ft ceiling height to top plat panel. Should the sprinklers be calculated flowing 6'-6" x 15'-0", or, flowing 13'-0" x 15'-0"? I believe a case could be made for both. It’s an all purpose room in a school basement. I could offer them OH 1 at 6'-6" x 15'-0" without changing spacing on the branches. I could only achieve Light Hazard if 13'-0" x 15'-0" is utilized. The architect shows minor changes for small closets, a few walls, and we're changing the sprinklers to quick response. Thank You very much. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 13 9.3.5.11.6 states 'For longitudinal braces only, the brace shall be permitted to be connected to a tab welded to the pipe in conformance to 6.5.2' 6.5.2.2.3 specifies that 'Tabs for longitudinal earthquake bracing shall be permitted to be welded to in-place piping where the welding process is performed in accordance with NFPA 51B.'
Section 6.5.2.4.7 states ' Tabs for longitudinal earthquake bracing shall have minimum throat weld thickness not less than 1.25 times the pipe wall thickness and welded on both sides of the longest dimension.' My questions are: Is anybody using this method for longitudinal bracing? How do you calculate a brace using this configuration? Is there a tab on the market specifically for this application? Additionally, is Section 6.5.2.2.3 suggesting that tabs are only permitted to be welded in field? We do giant open warehouses where bracing typically can go exactly where the plan shows it. We fab 90% of our pipe in-house, and if we could specify the tab's location on the fab listings, we could potentially get rid of 212 pipe clamps for all longitudinal bracing. Besides the obvious install issue of 'it might not work in the exact location it's welded' - am I missing something...? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe For a sprinkler pipe that is low enough above the finished floor that it could be walked into by a person of standard height, can it be wrapped in foam or soft material by code to prevent knocking one's head on it?
Alternatively, is it allowed to wrap this pipe in yellow tape or adhesive to increase its visibility to prevent running into it? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a project where the Specifying Engineer has noted to have a small hose connection for periodic (maybe every 6 months) building maintenance use to wash down a water intake filter.
They have specified that it be fed from the jockey pump upstream of the jockey discharge check valve and connection to the fire pump connection, so it would seem that it would not really affect the fire protection system or fire pump discharge. However, I don't think it is a good idea, and I think a separate pump for building maintenance should be provided. Looking to see if there is any code reference I can use for backup as common sense doesn't always work or maybe I am wrong. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is anyone aware of a horizontal sidewall sprinkler model that is listed for installation up to 18" below the ceiling?
I've searched high and low and can't seem to find one. This would be for a light-hazard application installed in a gypsum soffit with flat, non-combustible ceilings. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe How do you reconcile NFPA 30, 2021 Edition, Chapter 9 General Storage Requirements which reference NFPA 13, 2019 Edition, and vice versa?
NFPA 30 Section 9.6.1 says that the MAQ is doubled when the building is sprinklered per NFPA 13. NFPA 13 has the Extra Hazard Group 2 occupancy, which covers "substantial amounts of combustible or flammable liquids." The word substantial obviously makes it an engineering judgment for when EH2 should be applied. Hypothetical example: An existing warehouse is sprinklered per NFPA 13 to protect rack storage of Class I-IV commodities and cartoned group A plastics. The owner wants to store a Class III-B liquid in the existing warehouse on the storage racks. They would store more than the baseline MAQ but less than double the MAQ they get for having an NFPA 13 system. In my opinion, this storage arrangement would be out of the scope of NFPA 13, so the double MAQ for sprinklering per NFPA 13 would not apply. I'd require a protection scheme from Chapter 16 of NFPA 30. Do you disagree? What if they only wanted to store under the baseline MAQ amount? Would you require a protection scheme from Chapter 16 of NFPA 30? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe With a wet ESFR system overhead, would a double interlock in rack system be permitted below?
I would assume linear heat detection would be installed in the racks, not at the roof? These are oil storage racks and foam tray storage racks that require in-rack sprinklers. The customer has a problem with forklift/sprinkler head interaction. If allowed, I would assume the rack and overhead systems would need to be balanced. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When doing Calculations for a building that has a fire pump that is fed by an above-ground water tank, what do I use for available supply?
The fire Pump is 75 psi at 1,500 gpm. City water refills the water tank. City water is 104 psi static, 81 residual at 1,453 gpm flow. Do I factor in the tank by figuring the pressure created by elevation, or do I bypass the tank and use the city pressure in combination with the fire pump? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Does Phantom Flow apply to a 750 sqft Paint Spray booth?
Currently acting as AHJ for a spray booth sprinkler submittal. We commented that their hydraulic calculations must comply with 2022 NFPA 13 Sections 28.2.4.2.4 and 28.2.4.2.5. Are we correct in our interpretation that Section 28.2.4.2.5 requires an additional flow to be added, like a secondary hose stream allowance, so that the design discharge meets the minimum required discharge? In this specific submittal, it would require an Extra Hazard Group 2 (EH2) spray booth (approximately 750 square feet in area) to add additional flow in the calculation to meet the minimum EH2 design discharge of 1,000 gpm? (ie: 0.40 x 2500 = 1,000 gpm). The Appendix material seems to confirm this interpretation. It seems like overkill, but I cannot find an NFPA Section that would allow the minimum design area (2500 sqft) to be reduced for calculation purposes, even if the spray booth itself is only 750 sqft. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is a flow switch required on the discharge side of the fire pump on the pipe before it exits the pump room?
We have an approved job that does not have a flow switch, and the fire marshal is requiring one. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe If a bathroom is greater than 55 sq ft, but is compartmentalized into spaces less than 55 sq ft each, does the exemption from coverage apply to the compartments (assuming all other requirements apply)?
We have a bathroom where the toilet is separated from rest of the bathroom. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have an atrium on our project, and due to some changes in the interior design, fabrics (half circles drops) were added as shown in the attached pictures. This has an impact on my sprinkler coverage and obstruction. Can those fabrics (450mm depth) be considered as obstructed construction under NFPA 13 Section 11.2.4.1.2 (2) – NFPA 13 (2019 or 2022)? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Why is there a drastic change for limiting an NFPA 13R sprinkler system from a four-story, maximum 60 feet height above grade plane in IBC 2018 to the maximum of the top floor being only 30 feet above fire department access in IBC 2021?
Here, we have many townhomes (R-3 group) that could easily comply with the 2018 edition of the IBC, but they will exceed the top floor 30-foot limit of the 2021 edition of IBC. Also, the 2024 IBC tries to fix the drastic change by providing an exception for Group R-2 buildings by raising the top floor height limit from 30 ft to 45 ft. That's great and all, but townhouses are still considered R-3 buildings and do not qualify for the exception. How would you proceed for a townhome with a top floor over 30 feet above fire department access? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
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