NFPA 20 permits the demand for a suppression system to be between 90% and 140% of a fire pump's rated capacity (NFPA 20-2019 4.10.1 and Annex A.4.10.1). The pressure demand must always be less than the pressure supplied by the pump's performance curve along this range.
Does this concept apply to standpipes? For instance, could a 750 gpm pump provide 1,000 gpm demand for standpipes since it would be running at 133% of its rated flow? If it can be done, is it good practice? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
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When doing thrust block calculations NFPA 13 gives an angle that is the bend off the centerline of the original pipe.
What angle should be used for a tee or a dead end? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Where can I find a contractor the performs internal Water Storage tank inspections per NFPA 25?
The customer is have difficulty as the local contractors do not perform these inspections because of the age of tank and liability. The contractors I have spoken with say that the tank is not large enough to put divers in. The dimensions are approximately 25 -30 foot diameter, and approximately 25-30 feet in height. Then the contractors say due to the age of the tank there is a liability they are not willing to take on. One contractor suggested finding a company that uses drones. Any suggestions on how to proceed? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Is there a one-stop resource that shows selection of concrete anchors, steel clamps, and wood attachments for use with sprinkler systems?
Much of the manufacturer's information I have is just on products I've heard about or come across from contractors in the industry (familiar with Erico, Sammy's, Thunderstud, Hilti). If not (and you're a contractor), what manufacturer/brand lines do you use/prefer? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe In a recent discussion on threaded fittings versus welded outlets I heard that there's hanger implications - where a hanger is required for every piece of sprinkler pipe.
I'm not a designer so I apologize if this is an awful question, but is a hanger required for every stick of fire sprinkler pipe? If there's short stubs to change direction on a branch line I would think the hanger spacing would be adequate, but I figured I'd ask the pros. Thanks in advance. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Lately I have seen a couple specifications require branch lines to have threaded connections and they specifically do not allow grooved, even when Schedule 40 pipe is used and even when most of the armover connections are welded pipe outlets.
These could just be old/outdated specs, but is there a reason/theory that suggests threaded connections are better than grooved? They can be cheaper but also can increase labor costs on large jobs. Just curious if there's a perspective I'm not considering here, thanks in advance. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Is fire flow calculated on only one building at a time, or must all buildings in an area be considered when determining the required amount of fire flow?
We have a school property with one school that's comprised of many 'buildings' separated by fire walls. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I was reviewing a sprinkler plan using flexible house from an arm over. The head had a k factor of 5.6 and the flexible hose had a k-factor of 4.86 with the pressure and flow at the head. This seems like a mistake. Wouldn't you want a flexible hose with a k-factor of 5.6 or larger?
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Have a current project that is stalled due to water supply conditions. A water flow test was not conducted early in the project.
Options have been presented to the other responsible parties for consideration, however a particular party has rebutted with “Where does it say you can not go below a certain water pressure?” The existing water supply would be taken down to 6 psi and the questioning party wants documentation on the standards of the lowest psi a water supply needs or should not drop below. Can anyone provide or give direction on finding information regarding water supply requirements or standards which address minimum water supply requirements? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe What is the fire protection standard for CT-Scan, PET/CT, tomotherapy, etc. rooms?
NFPA 13 notes only that occupancies shall have automatic fire sprinkler system or an approved alternative. I have seen double standards in installed systems in one hospital project I worked in wherein the hospital AHJ proposed wet sprinkler system on one occasion while clean agent fire suppression system was used on another. My concern is that an unconscious patient left inside the gantry by staff in panic can die if the clean agent fire suppression system discharges in the treatment room. Whereas, on another hand, millions worth CT, PET/CT, tomotherapy machines can be seriously damaged beyond repair if the wet sprinkler system works to put out fire inside the room. It sometimes seems like a choice between protecting patients which is the core business of healthcare facilities or protecting costly property from damage. Is there an absolute standard to put a period to my query? Thanks. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Existing building with a vertical in-line fire pump that has not been tested in the last 5-6 years. The fire pump is fed from a water storage tank where the top of the tank is roughly 12-15 feet above the fire pump.
The fire pump is rated 55 psi at 500 gpm. There is about 60 feet of 4-inch main that connects the discharge side of the fire pump to the fire pump test header. This stretch of main also includes at least 6 elbows and a tee. The test header has two 2-1/2" connections. With a hose monster and 15-feet of hose connected to the pump test header, we are only able to flow about 400 gpm out of the test header. At this flow rate, the suction side fire pump gauge reads -20 psi and the discharge reads 25 psi. In short we are not getting the 100% flow (of 500 gpm) or the rated pressure (of 55 psi). I can see some flow being restricted due to the long run from the pump room to the building exterior, but are there other issues I'm not thinking about here that would cause this? Obstruction in the main perhaps? Any tips on actually getting the flow up to 100%? Thanks. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe We have to provide sprinklers 4 feet on center to protect the opening between a commercial kitchen and a seating area.
The number of heads to be calculated is based on the 1.2 times the square root of 1500 per NFPA 13 2007 Edition. W have first calculated the water curtain demand assuming each sprinkler needs to flow 15 gpm. We get a required pressure and flow for the end node serving the water curtain. The calculated flow/pressure is then used in the full calc to balance the remaining system around. So in essence we are calculating the system in two parts. Is this the correct methodology? As best I can tell the water curtain demand must be in addition and must be balanced with the remote area. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Are there guidelines/best practices for recommended pipe schedule in tall high-rise standpipe express risers?
The height could force the working pressure in the pipe to exceed 300 or more psi. Unless there is a better method I'm assuming the preferred joint is roll-grooved. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I'm new to this industry and I've been really trying to pick apart NFPA 13.
I have a question related to determining the area of sprinkler operation of a dry pipe system with high temperature sprinklers. The system is providing coverage of an outdoor chemical storage canopy. Design criteria: Dry System due to freeze potential Extra Hazard Group 1 (0.30 gpm/sf over 2500 sf) per NFPA 13 Fig. 11.2.3.1.1 High temperature rated sprinklers per NFPA 13, Section 8.4.7.2.4 My question is regarding adjustments to the area of sprinkler operation. Dry systems are to be increased 30 percent per 11.2.3.2.5, then it states in 11.2.3.2.6 that the area can be reduced by 25 percent when using High temperature sprinklers. Multiple adjustments can be compounded. Increase: 2500*30% = 750 sf Decrease: 2500*25% = 625 sf 2500 + 750 - 625 = 2625 sf A conservative approach would be to ignore the 25% reduction, but I'm curious what is actually required per code. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Are you allowed to run a branch line through an elevator machine room? ASME 17.1 Section 2.8.2.3 clearly states that you can. Section 2.8.2.3.1 disallows only risers and returns. Am I missing something?
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe What is the maximum height of a sprig allowed before a horizontal brace is needed? Are there any specifics on where the measurement is taken (from the branchline, or just the cut length of the sprig)? Any help is appreciated.
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Our University is currently in design of an Applied Research Center which is configured as two lineal building bars separated by an atrium space. One bar will house our shipping and receiving area for chemicals, flammables, and hazardous waste storage. The other building bar will contain the majority of wet and dry labs for research.
The only pathway for transport of these chemicals, flammables and hazardous waste is designed to occur through the atrium space. Also, the only way to transport these items to second floor labs is by a passenger elevator located in the atrium. I can find no references in NFPA that prohibits utilizing the atrium for transporting these items. Does anyone have any information on whether this process is acceptable or not? Thank you! Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Product data for multiple attic style sprinklers simply states that a hose allowance must be provided in accordance with NFPA 13 when using special application attic style sprinklers.
My logic, therefore, is that unused attic spaces show up as light hazard in A.5.2 (2016 Edition) and thus the hose allowance is 100 gpm for combustible attic spaces that don't house mechanical equipment or storage. Am I off base here? While it isn't my case I would think the presence of mechanical equipment or storage in the attic would bump the density at least to OH1 and 250 gpm for the hose allowance. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I'm a learning sprinkler designer and I have a question that's more about design efficiency.
When you lay out sprinklers in large Ordinary Hazard areas (assuming there's ceilings or unobstructed construction), what is the first step you take to drop sprinklers in the space? Do you calculate the area of the room and then determine, at a minimum, how many sprinklers you need? Do you use drafting tools to automatically optimize the layout? Do you have circles around the sprinklers for approximate coverage and repeatedly shift until you like the layout? I typically start with the area of the room and divide by 130 to determine the minimum quantity of sprinklers, then dimension each wall to start with an "optimum" spacing. I feel like this takes longer than it should, so I'm curious if there's a better approach I could be using. Any help is appreciated. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I recently came across your 13, 13R Summary of differences sheet and was wondering if you could explain or site a section that explains how NFPA 13R cannot be considered “fully-sprinklered” for code purposes? Thank you in advance for any help.
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I have other smaller cloud ceilings that do not exceed 4 ft., however I do not think the sprinklers above have the 18” above the cloud to develop their sprinkler spray, so my gut tells me that means sprinklers are required below the cloud. I think I have seen an NFSA informal interpretation that agrees.
However, what about 8.6.5.3.2 (2016)? NFPA 13 - 2016
Does that mean it does NOT really need the 18” in order for it to qualify for the following 8.6.5.3.3 rule for obstructions over 4 ft. wide? In other words, my cloud is not over 4 ft. wide, so doesn’t need sprinklers, even if the sprinklers above do not reach full spray development? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I know where I stand on this topic, but I'm interested in hearing other opinions and seeing if I'm wrong.
An existing, one-story, 35+ year old building that is a Seismic Risk Category IV building was not build to resist lateral loads. The building is being altered under a Level III alteration in the International Existing Building Code (IEBC), and is not required to be structurally braced nor is the sprinkler system required to be retrofit with seismic bracing. My question is, is there any benefit to bracing a fire sprinkler system where the building is not structurally built to resist lateral loads? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe The remote area for a wet hydraulically-calculated sprinkler system contains two different hazard classifications - Light and Ordinary Hazard Group II.
When using the density/area method of NFPA 13, is each sprinkler calculated only to the hazard within the room it protects? If the OH2 spaces are confined to small storage rooms (with walls and doors), does the OH2 density have to extend beyond the OH2 room at all? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe NFPA 24-2016: 10.10.2.5 Backflow Prevention Assemblies.
10.10.2.5.1 The backflow prevention assembly shall be forward flow tested to ensure proper operation. 10.10.2.5.2 The minimum flow rate tested in 10.10.2.5.1 shall be the system demand, including hose stream demand where applicable. My question is: When is hose stream demand applicable? Is this referring to inside hose streams or all hose streams? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I've seen floor control assemblies (isolation valve, sometimes a check valve, waterflow switch, test & drain) in many different configurations as far as spacing of each of the components. I also understand that several manufacturers make an "all in one" valve assembly that can have all of these components.
Is there any benefit to the operation of the waterflow switch by spacing out these components? I'm wondering if a steady stream from the test and drain that is further from the switch allows the waterflow switch to operate more consistently? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe |
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