|
Is fire-rated construction ever enough to not warrant sprinkler protection?
Is there a NFPA 13 section that would validate this one way or another? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
14 Comments
How would you recommend determining when PRV hose valves should be used in a highrise?
I am designing a 12-story hotel. The highest outlet is at 125'-5". Our flow test is mid-50's static and residual at 1,500 gpm. I did the standpipe calculation using a combined source of the city and fire pump. I sized the pump to what the demand was at 750gpm @ 174.26 psi. In turn I put in a 750gpm @ 125psi fire pump and had a 6.45lb buffer. Do I then do another calculation to find out the maximum static pressure available on the supply side at each level and minus out the elevation loss? Can anyone give me a guide on how to find out which level needs a PRV FHV and which doesn't? Thank you in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am designing a community tornado storm shelter and per ICC 500, Section 309.1, any penetration of the shelter envelope by a liquid line is to be provided with an automatic shutoff.
How is this being achieved with sprinkler pipe penetration? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When is a cloud ceiling a ceiling, and when is it an obstruction?
I have a project with a 2-story lobby that has a mezzanine waiting area and clouded ceilings. The clouds are 3'-10" wide continuous clouds that run east/west across the room. The rows of clouds are spaced 4'-0" apart from each other but will have lights and diffusers between them serving the space. Spacing between the clouds and the wall varies but narrowest dimension is 2'-0". Even better, the roof above the cloud ceiling is sloped greater than 2/12" and will require an increased design area and sprinklers at the peak. The architect's intent was to not require sprinkler coverage below the ceiling clouds and consider them an obstruction not wider than 4'-0". I am not as comfortable with this but wanted to bring it up for discussion. I did see a forum post about this come up in 2022 but was wondering if anyone had additional comments. Thank you! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Concealed Fire Alarm Devices: I am looking into specifying concealed fire alarm devices for a project. I have two major questions:
1. Are concealed fire alarm devices reliable? I have heard second-hand that concealed fire alarm devices do not always function. 2. Are there a variety of manufacturers? I did a quick Google search and have only been able to find one manufacturer. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a wafer check or grooved check valve be installed directly on a fire pump discharge flange?
I've found they affect the pump performance by 3 to 8 psi. When testing we found this true and moved it by a foot. The pump didn’t hit its curve and was fairly new. Shouldn’t NFPA 20 or manufacturers be aware of this? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe As many/most of us know, there's an internationally standardized pictogram (symbol) for exit signs that's common in many countries worldwide. However, it's not yet common in the US, likely due to what appears to be a misconception that the IBC/IFC only allows "EXIT" lettering. IBC/IFC Section 1013.5 requires internally illuminated exit signs to be listed to UL 924. (There's a different section on externally-illuminated exit signs, 1013.6.1, that specifies "EXIT" lettering, however, the vast majority of exit signs are internally-illuminated and therefore not subject to anything under 1013.6 due to that section's scope clause.) UL 924 was revised a while back to allow the internationally standardized pictogram, including in lieu of "EXIT" lettering. (see section 42 of UL 924) Therefore, my impression is that a UL-listed internally-illuminated exit sign that uses the internationally-standardized pictogram complies with the IBC/IFC. (There are such products currently on the market.) Are UL-listed internally-illuminated exit signs using the pictogram in compliance with IBC/IFC? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Hydraulic Upgrade to old wet and dry systems and determine "C" factors to be used. Question:
We plan to upgrade a fire sprinkler system from a Pipe Schedule Ordinary Hazard system with k-5.6 standard response heads to 0.25/2000 sqft with k-8 sprinklers, what "C" factor should be used? The system is 55 years old and has a good water supply that would easily work for a new system using a C=120; however, debris has built up in the pipe, and if we were to do a hydro-pneumatic flush, the roughness would be much worse than that of new pipe. The AHJ has no answers other than to do what we feel is best, and the insurance company just wants to see the density increased and "proven" to work at 0.25/2000. Furthermore, there are 2 dry systems that are 55 years old, and they want these upgraded, too. Even if we add a pump, it's just going to slam the sludge to the end of the lines and plug up any new heads that are installed. Do you have any thoughts? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Does anyone know the historical context of why a 90-minute door is permitted on a 2-hour barrier?
Why the 30-minute difference? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Doing a mechanical machine room, and I need to add sprinkler coverage above and below ductwork.
I was told that if you have 2 sprinklers (one covering above the ductwork and one covering under the ductwork), you can run 1-in pipe to each. So here is the example: I have 4 sprinklers coming off a branchline but 2 of those are under ductwork. The uprights that are above and below are covering the same area. What pipe size do I need to use for this branch line? What code justifies this one way or another? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am designing a sprinkler system per FM requirements.
I have areas containing storage within non-storage occupancies, therefor I'm following FM Global Data Sheet (FMDS) 3-26. The storage area meets all of the limitations of Incidental storage. My question is, if the hazard class of the space is deemed HC-1 or HC-2, are the sprinklers protecting this area required to be FM-approved storage-type sprinklers...aka K11.2 sprinklers? If so, this would then tighten up my spacing to 100 sf? My ceiling is 11'-0. Thanks in advance for any help. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am working on a project with a diesel fire pump room that is Extra Hazard 2 (0.4 gpm / 2500 SF). The room is only 300 SF, which is well below 2,500 SF. The 2022 Edition, NFPA 13 28.2.4.2.4, indicates following a set of steps shown in A.28.2.4.2.4. This section indicates that if the flow is less than the minimum required flow, then the difference in flow must be added to a node on the system. A.28.2.4.2.5 shows a picture example of where to add the flow. The current design has 4 sprinklers within the room, each discharging around 30 gpm ((0.4 gpm x 300 SF) / 4). When reviewing the shop drawings, 880 gpm was added to a node, increasing the system pressure to about 150 psi! How is NFPA 13 28.2.4.2.4 supposed to be accurately calculated within the hydraulic calcs? Do you create an imaginary system and, in this case, add 21 more sprinklers for a total of 25 (2500 / 100 SF per sprinkler)? Adding the 880 gpm to the system shown on the shop drawings and getting a required pressure of about 150 psi doesn't seem right.  Does 'cold solder' specifically mean that one sprinkler gets another wet, or does it mean that one sprinkler keeps the floor area cool enough so the adjacent sprinkler doesn't activate?
Or is it both? I've recently had several conversations in which the other party was convinced that cold-soldering can only occur when one sprinkler wets and cools another sprinkler's thermal element. I was taught a long time ago that cold-solder referred to one sprinkler keeping the floor area wet and cool but not wet enough to effectively put out or control a fire, thereby allowing the fire to 'skip' to the next sprinkler, allowing the fire to grow larger than had both adjacent sprinkler heads activated properly. Obviously, if a sprinkler gets wet and does not activate, it causes the same problem. It makes a difference in my mind because, at soffits or varying ceiling elevations, the lower sprinkler could spray into the higher sprinkler's floor area. If the vertical change is 36" or greater, NFPA says to treat it as a wall, and sprinklers must be 1/2 x S from this plane. In my mind, the differences in ceiling height would effectively create a baffle, and neither sprinkler would actually wet the other. However, if they were closer than 6'-0 measured on a flat horizontal plane, they would still be cold soldered since one sprays into the floor area of another. I see this all the time. Do you have thoughts on this? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe This is a corner exit stair in a 2-story Type II-B building. There is 2-hr fire separation per client request (only 1-hr by code). There's one column in the corner that only supports exterior precast walls and roof structure. Does it need to be fireproofed? I would assume it doesn't. Any ideas? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  I have 18 years of experience in sprinkler design, and I have a NICET Level 3 certification.
The company I work for is asking me to hold the License in three states because the previous holder is leaving. I have read the verbiage stating I would be responsible for everything, including the contracts. That seems scary to me. In your opinion, is the additional responsibility worth it, money-wise? I don't want to sell myself short, but I also want to be fair. Do you have any suggestions or tips on how I should be thinking about this? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe The 2018 IBC, Section 1009.7 for Exterior Area for Assisted Rescue (EAAR) requires exterior walls within 10 feet to be rated 1-hour for exposure to fire from the inside.
When a window is located within 10 feet of the EAAR, can it be protected with a window sprinkler system? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe What occupancy would you classify two sleeping rooms in an office building (otherwise B Occupancy)?
The area of the two rooms is 400 sf, and the area of the offices is 6,870 sf. Will the rooms be R-2? Does the building need sprinklers as a result? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have an instance of "flowswitch cycling" on a new wet-pipe system. The RPZ backflow is thought to be causing the flow switch to fluctuate and, therefore, not get us the flow alarm in a timely manner or at all. We have opened the manual high point air vent and flowed for several minutes with no success. Has anyone had this or found a solution to it? Potter has a technical bulletin on this but does not go into detail about how to resolve it. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Regarding forward-flow testing, I have read that a main drain (if sized appropriately) can be used in place of other means. This was in the 2016 NFPA 13 A.8.16.2.4.2, but I cannot locate it in the 2019 version.
With that, what is the best practice for testing at the time of system acceptance? Without being able to use a hose monster, is the main drain test sufficient to ensure the backflow fully opens? Other than hydraulic calculations, how is it proven that we have an acceptable result? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a client who owns multiple assisted living facilities. It's residential construction with attic insulation on the roof trusses' bottom chord, and louvered gable ends with ridge vents.
They have existing wet pipe sprinkler systems in the attic and have experienced busted sprinkler lines in the past. They want to heat the attics to prevent this with electric heaters. I have done the heat loss calculations and have determined the heating load would be more than their current electrical service can support. The only options I see available are heat trace, anti-freeze, or conversion to a dry system. Anti-freeze with UL-listed anti-freeze was my first thought, but it looks like a backflow preventer would have to be added. Does anyone have experience with this and/or have recommendations on how to address this? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I understand the definition of the "Common Path" from Section 3.3.49 in NFPA 101, but within the examples it is up to the point when you reach a corridor and have the two exit alternatives. In a case like the one in the image shown below, the orange area is very wide, or open space, up to where they would measure the common travel distance. At what point does the path of common travel stop in a scenario like this? What is that threshold?  Is there any way to install sidewall sprinklers in a room with sloped ceilings?
Say you had a rectangular room with a ceiling attached directly to the underside of a traditional gable roof with a high ridge peak in the middle. Concealed pendent ceiling sprinklers are often not possible because the space above the ceiling is completely filled with insulation. Can you do sidewalls on the vertical walls near the ceiling high point to protect the room? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Thank you to everyone for sharing your expertise and making this community stronger. Special shout-out to our Top Contributors for September 2024—you keep this place awesome!
Do OSHA safety regulations apply to RPZ and DCDA backflow preventers?
OSHA requires 30 inches to the face off a side wall for maintenance for horizontal installations. My contention is that if the drain to the RPZ runs to that wall, you will have an obstruction and trip hazard, and it will not be accessible for maintenance. I've also installed the RPZs 4 feet above the tight pump room floors for access. It's never been a problem. Please advise. IBC says to install backflow preventers according to the manufacturer's instructions. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
ALL-ACCESS
SUBSCRIBESubscribe and learn something new each day:
COMMUNITYTop June '25 Contributors
YOUR POSTPE EXAMGet 100 Days of Free Sample Questions right to you!
FILTERS
All
ARCHIVES
July 2025
PE PREP SERIES |
RSS Feed
