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.

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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.

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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? 

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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.

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Solution | Posted 07/09/19

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!

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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.

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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.

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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.

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Who is responsible for coordinating the inspection, testing, and maintenance activities of water-based fire suppression systems?
a. monitoring company
b. owner
c. insurer
d. inspecting contractor

Solution | Posted 07/02/19

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

• 8.6.5.3 Obstructions that Prevent Sprinkler Discharge from Reaching Hazard
• 8.6.5.3.2 The requirements of 8.6.5.3 shall also apply to obstructions 18 in. (450 mm) or less below the sprinkler for light and ordinary hazard occupancies.

• 8.6.5.3.3 Sprinklers shall be installed under fixed obstructions over 4 ft (1.2 m) wide.

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?

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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?

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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?

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A forensic study is being prepared using a fire model to attempt to verify whether arson could be a cause. If the fire's origin room ceiling ceiling (3.3 m) has an initial temperature of approximately 22 deg C and is exposed to a plume along the ceiling at approximately 85 deg C traveling around 1.2 m/s, what is the activation time (in seconds) for a quick response (RTI of 40), Ordinary Temperature (75 deg C) sprinkler?
     a. 61 s
     b. 67 s
     c. 210 s
     d. 230 s

Solution | Posted 06/24/19

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?

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​A horizontal split-case electric fire pump is serving a seven story high rise with modifications on the upper level. If the pump is rated for 68 psi at 750 gpm (58 brake hp) and keeps a constant impeller diameter, what will the new brake horsepower be if the speed is increased from 1790 rpm to 1850 rpm?
a. 56 hp
b. 60 hp
c. 62 hp
d. 64 hp

Solution | Posted 06/20/19

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?

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Is there a reason why OS&Y would be better on backflow preventers for fire suppression systems over butterfly valves?

One application where we often must use the OS&Y is when the backflow serves a fire pump and we don't want to distort the flow and cause cavitation at the pump - but otherwise the butterfly valves are a major space saver. Just curious if others feel differently or if I'm missing a major benefit to the OS&Y type.

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Solution | Posted 06/17/19

The 2015 Edition of the International Fire Code added some clarity for water supply for buildings with automatic sprinkler systems.

The Annex B material (not enforceable unless adopted) states:

B105.3 Water supply for buildings equipped with an automatic sprinkler system. For buildings equipped with an approved automatic sprinkler system, the water supply shall be capable of providing the greater of:
1. The automatic sprinkler system demand, including hose stream allowance.
2. The required fire-flow.

In the past I've heard several people say that only inside hose allowances are included when determining the total volume required (which sizes the water storage tank). Would you interpret this section of IFC to include both the inside and outside hose allowance?

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Solution | Posted 06/14/19

Where concrete anchors are used for seismic bracing, they must be "prequalified". Is this just an additional listing that is required to meet ACI 355.2? 

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In general, when designing fire sprinkler systems with a fire pump, is your philosophy to only provide the minimum fire pump size that is needed to support your system, or do you often increase the fire pump size to decrease pipe sizes on the system?

How much are you typically willing to increase a fire pump size in order to benefit the pipe sizes throughout your project?

When I first learned about how to size a fire pump, I was told that if your system gets over 100 psi then you might as well size the pump to get as close to 170-175 psi on the system as possible - the reason being that the cost to upsize a fire pump is less than the savings associated with smaller mains and branch pipe.

I'm not sure that there's a hard-and-fast rule of thumb, but I'm just interested if other people use the same strategy or if it's entirely dependent on the type of job and size of the job.

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What is the ideal approach for fire sprinkler pipe to enter a building?

I find many engineer details show either an in-building riser (by Ames) or a ductile iron pipe with restrained pipe and fittings come under the building foundation and up into the building.

While this approach is acceptable, if we have the ability to coordinate with the structural foundation during design, would it not be better to drop the footing so that the fire sprinkler pipe can be sleeved through the vertical portion of the foundation wall?

I would think that running through the foundation wall would put far less pressure onto the pipe and joints itself. I understand when most installation/design work is completed is usually well after structural design, but when we do design upfront wouldn't this be the best-case scenario?

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On recent inspections I've seen many installations where an automatic ball drip is not provided anywhere on the pipe connection between the fire department connection and the check valve that serves the fire department connection. Is there an exception I'm missing or isn't that automatic ball drip always required?

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