A new-construction church is to contain a main sanctuary and stage, complete commercial kitchen with lounge seating area, and a connected enclosed parking garage. What is the most hazardous fire sprinkler occupancy for this facility?
a. Light Hazard
b. Ordinary Hazard Group 1
c. Ordinary Hazard Group 2
d. Extra Hazard Group 1

Solution | Posted 07/17/20

Indicating valve (Butterfly vs Gate Valve) Requirement in Fire Water Mains:

NFPA 24, Section A.3.3.17.1 (Edition 2019), suggests to use OS&Y gate valves, butterfly valves, and underground gate valves with post indicators.

I understand that any type of valve are acceptable to use and I've seen frequent use of butterfly and gate valves in underground main. OS&Y requirement is quite clear.

Based on my understanding, butterfly valves are less prone to corrosion and ferritic buildup when compared to gate valves due to its body design.

My understand is that gate valves, due to buildup, might be prevented from closing and would require an entire systems or section of a system to do any maintenance. Yet, direct-buried gate valves are still preferred for underground mains and I'm not sure why.

The cost difference does is not enough in my case to use gate valves specially for 8", 10" 14" or higher sizes.

Is there some reason for gate valve preferences over butterfly valves?

If a butterfly is used I could possibly see a pit being required for maintenance, but NFPA standards do not address pit requirements for a butterfly valve.

Is there any other consideration would be helpful to consider when using butterfly vs gate valves, for underground or even aboveground applications?

Any suggestions would be much appreciated.

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Determine the flow (in gpm) through a residential sidewall K4.2 sprinkler at 10.1 psi.
a. 13 gpm
b. 18 gpm
c. 21 gpm
d. 42 gpm

Solution | Posted 07/16/20

Have a situation I've never crossed before: we have a very small building that's getting expanded. Originally the sprinkler contractor gave two options for the general contractor to price their underground fire sprinkler service - (1) is to provide a 2-1/2" main, the other (2) is to provide fire barriers in certain areas with automatic door closers to allow the room design method be used, and bring in a 2" underground.

I completely recognize that small underground pipe is not good practice and limits the future potential of the building. We recommended a 4-inch underground, but the increased cost for tap fees and underground pricing added $10-15,000 to the job which the owner adamantly refused.

We were given notice to proceed with 2-1/2" underground and thus provided a 2-1/2" riser and 2-1/2" mains. 

The GC gave a different direction for the underground and pulled 2" underground and is providing fire barriers and automatic door closers.

We've recalculated using the room design method and everything still works with the 2" underground, but the 2-1/2" riser and 2-1/2" main is already ordered and on the way to the jobsite.

Does NFPA 13 have any restriction against having a larger riser or main size than the underground?

Because of the change in building construction, we only need a 2" riser and 2" main but will instead already have prefabricated 2-1/2" in both. My thought is to have a permanent placard clearly affixed to the riser showing the situation and clearly identify on as-builts the methodology used.

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Which of the following arrangements is not permitted for a new prison, under NFPA standards?
a. Sprinkler Protected, Type II (222) Construction, High-Rise Building
b. Sprinkler Protected, Type II (000) Construction, 3-Story Building
c. Sprinkler Protected, Type IV (2HH) Construction, 2-Story Building
d. Sprinkler Protected, Type V (000) Construction, 1-Story Building

Solution | Posted 07/15/20

We have an auditorium with a stage area. The stage area is fully sprinklered and provided with four natural smoke vents at the roof.

Below the smoke vents at a depth of almost 10-feet (3 meters) there is structural steel frame (provided for structural stability) arranged with narrow gap of only about 1-inch (30 mm) and obstructing all the smoke vents. We understand this steel frames will deflect the smoke plume and affect the performance of smoke vents.

Is there a standard/code reference regarding how to include this obstruction in the calculations and to prove to AHJ that the smoke vents would still be sufficient?

Thanks in advance.

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A portion of a home-improvement store has K11.2 ceiling-only sprinkler protection above double row racks. The owner is looking to store bagged charcoal (without any impregnated ignition fluid or plastic wrap) atop reinforced plastic pallets in this area. What would the commodity classification be for this arrangement if no plastics are intermixed?
a. Class II
b. Class III
c. Class IV
d. Group A Plastic

Solution | Posted 07/14/20

NFPA 24, Section 7.1.1.2 (2016 Edition), states that control valve shall be installed in each hydrant connection.

What is the purpose of this control valve, other than facilitating maintenance?

Would this be considered a "control valve" per NFPA 24 3.3.3, and does this have to be a post-indicating type valve?

Solution | Posted 07/13/20

I have a covered mall under 30' tall that requires hose valve connections in accordance with the International Building Code, Section 905.3.3.

Do these hose valve connections count as a standpipe that requires a monitored isolation valve as per NFPA 14 6.3.2?

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Solution | Posted 07/10/20

Should return air duct smoke detectors associated with a fan system close only the associated damper and shutdown the fan or close all dampers on the system (including supply return spill and outside air)?

How should outside air and spill air fire smoke dampers be controlled? Should these to be controlled by fire alarm?

Thanks in advance.

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Solution | Posted 07/09/20

When performing hydraulic calcs for NFPA 13 residential occupancies, what is the best approach to address small Ordinary Hazard rooms, such as janitor's closets or laundry rooms located on an otherwise-residential floor?

Room design is not always an option due to the prerequisites listed in NFPA 13, but area/density seems excessive when the calculation method given for residential occupancies is the 4 most demanding adjacent heads.

A 1,500 square foot area seems to go well beyond this approach, defeating the purpose of the residential design method. Other than room design, is there a justifiable code basis for calculating only the heads in the most demanding ordinary hazard room on such a floor?

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A 4-inch schedule 40 main is routed parallel in-between two beams and requires a trapeze hanger. The main is 2 ft. from one beam and 8.5 ft. from the other for a total span of 10.5 ft. What is the smallest schedule 10 pipe diameter capable of supporting this main as a trapeze hanger?
a. 2-inch
b. 2-1/2 inch
c. 3 inch
​d. 3-1/2 inch

Solution | Posted 07/08/20

We are having a discussion in our office; we are doing a 14,000 square foot addition. The existing riser has 2 systems that are approximately 40,000 square foot each. On the middle of one of the systems there is a dry system for the loading dock.

Does the dry system count as its own system or is it included in the 40,000 square feet for purposes of a total system area?

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This week is the third of our 2020 PE Prep Series - it's 20-weeks worth of mini Fire Protection PE Exams. 

Each week we'll post the leaderboard here with the results of that week's exams. To see full leadership board and more details, visit the PE Prep Series page here.
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Solution | Posted 07/07/20

I am working on a project with an attic. The pitch of the attic is 12:12 and the structure is combustible construction. The area is being used as a mechanical room so the fire sprinkler layout will be Ordinary Hazard Group 1 and a wet system will protect the space since the temperature will be maintained above 40ºF. Standard spray sprinklers are being utilized because Attic sprinklers are only listed for Light Hazard use.

Using a quick response area reduction, the remote area will be 1,500ft² (OH1) x 1.3 (30% pitch increase) x 0.6 (40% quick response decrease) = 1,170ft².

Since the sprinklers are spaced along the 12:12 pitch, the floor area in plan view is substantially less than the square footage being protected along this steep slope which picks up a ton of sprinklers when I draw my remote area based on the floor. I can't find any guidance in NFPA 13 about remote area on a slope besides the typical 1.2 x √RA split between sprinklers.

Should the 1,170ft² remote area be measured based on the coverage of the sprinkler along the slope (as the protection is spaced) or should the remote area be based on the floor even though it picks up way more sprinklers than 1,170ft² of actual coverage based on the slope?

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Anybody in this group has experience to design or approval of parking stackers inside the building?

This is outside the code will be reviewed as Amended Means & Methods.

They occur on two different projects (1) The Car's engine shall be off when enter the parking garage and electronic left will park the cars in stack, and (2) The car will be driven inside the garage to platform to be parked.

In both cases the fire sprinkler design density, exhaust system and means of egress requirements are in question.

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Thanks to everyone on the forum for another record month. This site was created exactly for the fire protection knowledge sharing, and it is your input and expertise that makes it happen. Here are the top commenters for June 2020:

I am currently renovating a lab for a healthcare facility and am trying to figure out which NFPA 13 hazard classification an autopsy or morgue would be under.

Any suggestions?

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We have an exit enclosure that is rated as Class I Division I. My understanding of an accessible route and means of egress, is that it is a "safe" means of egress.

Can an accessible route have a Class I Division I (explosion hazardous classification), or does it need to be purged and pressurized according to Type X requirements?

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