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Can black steel be used for trapeze support? We have a project where the contractor has hung the sprinkler pipe with trapeze hangers from a piece of black steel pipe, anchored to the deck instead of directly to a piece of Unistrut or angle iron. Looking at NFPA 13 Chapter 17 (17.1.2, 17.4.1.3.1), it seems like this method is not allowed. Can you provide some insight as to whether this is allowed, or the pipe needs to be Unistrut, angle iron, or something else? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe 
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For the protection of steel columns using sidewall sprinklers, what is the k-factor and temperature rating needed?
The existing upright sprinklers for the high-piled storage are 286°F. I couldn't find information for this in NFPA 13 2022. Any help or advice would be greatly appreciated. Thanks in advance! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Hi all, we are working on a project where we have installed a dry preaction system, with a main pipe along the ceiling, which has a conventional upright protecting the upper sections of the area, while pendent sprinklers protect the lower parts of the area. Pendents are standard response sprinklers. Length of the pendent is around 16 inches (400 mm). I would like to understand a few things related to the dry system: Are these systems pressure tested pneumatically or hydraulically, or both? If tested hydraulically, water will be drained, but the pendents will still be filled with water, correct? Is this acceptable? The temperature is the area that should be above 68°F. The pipe is galvanized. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  NFPA 13, 2019 Edition, Section 8.6.22 states, "Premixed antifreeze solutions of propylene glycol shall be permitted to be used with ESFR sprinklers where the ESFR sprinklers are listed for such use in a specific application."
Are there any current ESFR Sprinklers listed for use with antifreeze? I am currently only finding obsolete sprinklers that were listed for such use. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Regarding the QR sprinkler reduction: where does the -3 formula slope come from and where does the +55 come from in the equation Y= -3x /2 +55?
I've asked a few designers and they don't know. They said it is just something that is "Baked in," much like the Hazen-Williams formula, which includes elements we just accept. However, I'm just curious and like knowing things like that. Thanks for any help. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We're replacing old fire sprinkler systems in an existing warehouse in the mid-atlantic region with new ESFR systems.
The old warehouse house skylights every 25ft (which is a lot more than we see in new warehouses being built). No sprinklers are required in the skylights due to the size, however the number of skylights does raise questions about ceiling temperature. NFPA 13, 2016 Table 6.2.5.1 shows a maximum ambient ceiling temperature of 100°F for ordinary temperature sprinklers. It seems unlikely that the ceiling temperature would exceed 100°F in an occupied warehouse space (even on a hot summer day), so I'm thinking it make sense to install all ordinary temperature sprinklers (besides around unit heaters) to not delay sprinkler activation, but it looks like the newer editions of NFPA 13 allow of intermediate temperatures to be installed throughout warehouses. Is anyone seeing all intermediate temperature sprinklers installed in warehouse systems to prevent accidental discharge? NFPA 13, 2016-2025 all essentially say sprinkler temperature ratings for ESFR shall be ordinary unless Section 8.3.2 / 9.4.2 require intermediate- or high-temperature sprinklers. (Section 8.4.6.5 in 2016, 14.2.6 in 2019-22, 14.2.5 in 2025) Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe During on-site install (such as grooving, threading, and collisions during handling), its possible to damage the galvanized layer of the pipe.
How should we best address this? Is spraying anti-corrosion paint on the damaged areas the best option? Something like a galvanize spray or are there other better treatment methods? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm looking at the Idle Wood Pallet Table, 20.14.1.2(a) in NFPA 13, 2019 Edition.
Below the table there's a note saying if using 11.2K or larger K-factor sprinkler or high-temperature rated 8.0K sprinkler, the design area can be reduce to 2,000 sqft. But the table notes anything over 6 ft storage require 11.2k sprinklers with various area of operation over the 2,000 sqft. If what I'm reading is correct, is there a reason to use any of the area of operation noted in the table instead of the 2,000 sqft, since I be using 11.2K anyway as required? I feel like that note is only really directed to the < 6 storage height for an option to use 11.2K to decrease the area of operation from 3,000 to 2,000. Is that right? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can an ESFR system protect extra hazard occupancies such as plastic injection molding operation using combustible hydraulic fluid?
If not, what is the concern? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Following up on the recent post about components of a wet-pipe riser assembly, I have noticed many contractors (including places where I have worked) typically install a basic shotgun-style riser with no check valves on the riser assembly, while others opt for a riser check or individual check valves added to the shotgun risers as their standard. (I'm not talking alarm valves)
I know sometimes there are benefits to having check on individual risers, but in cases where the check is not a requirement, what are the considerations people factor-in when making the decision whether or not to install riser checks? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a project with a very large Water Storage Tank that requires a 20" suction line from the tank to the suction manifold side of (3) pumps.
Per NFPA 20, at the connection point from the water storage tank to the supply line to the fire pumps as required by NFPA 20 (2019 ed.) 4.16.6.5, where the pump and its suction supply are on separate foundations with rigid interconnecting pipe, the pipe shall be provided with strain relief in Figure A.6.3.1(a). We can find no manufacturer that has a 20" UL/FM strain relief connection. We do, although, have a supplier that makes a 20" Flexible Double Expansion Joint, but not UL/FM Listed. Does anyone know of any other options, or can we just use this flexible expansion joint and get a waiver from the Fire Marshal and EOR? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Hi everyone, I’m looking into the compatibility between UL-listed K-factors and European classification under UNI EN 12259-1. Specifically, I’m reviewing a Viking upright sprinkler (presumed marked 5.6 gpm/√psi), with the typical UL listing and a 1/2” NPT thread. The orifice appears to be in the 10 mm nominal range. According to Table 3 of UNI EN 12259-1, a 10 mm nominal orifice corresponds to a K-factor of 57 ±3 l/min/√bar. However, UL 199 allows sprinklers to be classified as 5.6 even with some variation in orifice geometry, and the unit conversion from 5.6 US gpm/√psi gives approximately 80 l/min/√bar, which seems inconsistent with the European 10 mm / K57 classification. Have you encountered UL-listed 5.6 sprinklers that, due to actual geometry, fall within the K57 class under UNI EN? Are there known cases where K-factors "overlap" across standards? An excerpt from UNI EN 12259-1 Annex C below. Thanks for your insights — I'm trying to understand how this is approached in practice during technical evaluations or retrofitting in Europe. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  I have a horizontal standpipe Class 1 in a 157,252 sqft warehouse that needs calc'd, but I'm trying to figure out how to go about that.
Per NFPA 14, 2016 edition, it seems to me that you would have the hydraulically most demanding hose valve flow 250-gpm @ 100-psi, and then flow three (3) more hose valves at 250-gpm until I get to a 1000-gpm total. However, Section 7.10.1.2.2 only says to do this up to 3 hose valves total. What am I doing wrong? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe How do you dispose of foam after the test (non-fluorinated)?
No one seems to know what to do with it. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe While water curtains can be used in lieu of a fire-resistant rated proscenium curtain to separate light and ordinary hazard areas, could the water curtain be deleted if the entire area was protected by a properly designed and installed ordinary hazard sprinkler system?
Essentially, trade increased coverage for the water curtains? Example - all large stages and theaters, and small ones like all-purpose rooms with stages. Hose valves, if required, would remain. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a project where they are retrofitting a sprinkler system in an old building. The structure is hollow block with lathe & plaster applied to the exposed side of the hollow block.
Does anyone know an approved method to hang pipe greater than 1"? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe This is a backflow preventer retrofit project where I'm trying to figure out what the system's original design criteria was.
I am working with an existing 7,300 sf warehouse area within a larger building, which includes offices and a workshop. It is a marine operation, and the products stored are primarily spare boat parts, propellers, shafts, brackets, housings... large metal objects stored in wood crates or cardboard boxes. I have determined this to be Class II Commodities, stored no higher than 20'. I am thinking that, based on NFPA 13-2019, Table 21.4.1.2 and Figure 21.4.1.2(b) curve B, I need a density of 0.3725 gpm/sf over a 2,000 sf area. I would also be required to have a maximum protection area of 100 sf based on Table 10.2.4.2.1(d). Here's where it gets tricky - the branches are spaced roughly 15' apart, and heads are spaced 8' or more along the branch line. Some are as far apart as 11'-6". The heads are K8.0 solder-type. Because of the K-rating, this shouldn't be a pipe schedule system. Is anyone aware of an alternative storage protection method that this system may be designed to? The installation date is 1986. Any thoughts would be greatly appreciated. I do not know what density I should be applying to this area in my calculations. Thank you very much! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a project with a 40,000 sf refrigerated storage area with an exposed metal deck roof with steel joists. Roof is sloped; the low end is 29-ft floor to deck and the high end is 31-ft 8-in.
Can I use the sprinkler criteria of 30-ft max ceiling height for storage areas of this space that are below the roof, where it is 30 ft or less, and use different sprinkler criteria where the roof exceeds 30 ft? More specifically, do I need to use the maximum roof height for the sprinkler criteria of the entire space? My issue is that there is rack storage and palletized storage, and FMDS 8-9 does not have a ceiling-only solution for palletized storage with a ceiling height greater than 30 ft. Any insight is appreciated, thanks. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Another fantastic month of discussions! Hats off to July 2025’s Top Contributors
Can an outside horn and strobe be used for a general alarm, or just for water flow only?
I can't find anything specific in NFPA 72, 2016 edition. Is it more of an AHJ call? I can understand where it could be a nuisance if used for general alarm notification. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Per the 2019 edition NFPA 13, Section 9.2.4.1.1, you can omit fire sprinklers within a small bathroom not exceeding 55 square feet that have walls and ceilings of noncombustible or limited-combustible materials with a 15-minute thermal barrier rating.
Now, if you read further down in section 9.2.4.2 relating to closets and pantries, it states, "surfaced with noncombustible or limited-combustible materials. So in section 9.2.4.1.1, are we talking about the sheetrock walls and ceiling or the construction of the walls and ceiling? If the bathroom walls and ceiling are constructed of wood but are covered with sheetrock, are the sprinklers still allowed to be omitted? I think it's confusing when they specify "surfaced with" when they are talking about the closets and pantries. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm working on a tenant improvement for a retail storage for a very large & common phone company. The architectural plans list the occupancy as Business.
I’ve designed one of these before, and when I pulled up the drawings from that previous job, the architect labeled it as Mercantile, so I designed it at 130 sqft spacing under Ordinary Hazard Group 1. Now, on this current project, there's no mention of Mercantile—only Business. The space is straightforward: a sales floor and a restroom in a 1,218-square-foot area. Can this be designed as Light Hazard? Looking at NFPA 13 (2019), Section 4.3.3 – Ordinary Hazard (Group 1) (using NFPA Link), the enhanced commentary refers to OH1 as covering “most light manufacturing and service industries where the use of flammable and combustible liquids or gases is either nonexistent or very limited.” That doesn’t really sound like a retail cellphone store to me. Even in the Annex, A.4.3.3 OH1 (6): Electronic Plant—this doesn’t seem anywhere near that level of hazard. Could someone help me out here? I get that I could just design to 130 sqft spacing and be safe, but I’m really aiming to understand and apply the right classification—not just overdesign. Trying to be the best, most informed designer I can be. Thanks for your time and any insight! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
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