When are standard response sprinkler heads a better choice than quick or fast response heads (5mm vs. 3mm bulb)?

Are there applications where it would be preferable to have a slower response time?

As far as I know, quick and standard response heads cost the same, come with the same k-factors, and the same temperature ratings.

Why would the slower one be chosen? When would you choose a Tyco TY-B instead of a TY-FRB?

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Is there a possible error in the definition of a "Cryogenic Fluid"?

The IFC, NFPA 400, and NFPA 55 all define a cryogenic fluid as "A fluid having a boiling point lower than -130°F at 14.7 pounds per square inch atmosphere (psia) (an absolute pressure of 101.3 kPa)."

Following that exact wording of this definition, virtually every gas would be considered a Cryogenic Fluid. Fluids, while not defined by any codes, are either gases or liquids.

The air we breathe has a boiling point of -317°F at 14.7 psia. Air is a fluid.

Clearly, this is not the intent of the ICC or NFPA. The NFPA Handbook indicates that a cryogenic is a liquified gas kept below 130°F. The definition should be changed to "a liquid having a boiling point under...." from "a fluid having a boiling point under...."

Have any fire protection professionals ran across a situation like this where the strict definition was incorrect? How did you handle it?

I am considering just making a paragraph in my report explaining my logic and going along with my day. Or would you not even bring this up with the AHJ because the intent is clear?

Thanks in advance.

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We have a military project (UFC 3-600-01 and NFPA 101 criteria) with 1/2-hour fire-resistance-rated fire barriers between each sleeping unit.

Each 1/2-hour wall consists of gypsum on each side of a metal-studded wall. The gypsum runs within about an inch of the floor in each room (not touching the floor, intentionally, to avoid soaking up moisture/water) where it has metal stud on the backside. 

Is firestop required along the base of the gypsum to maintain the 1/2-hour rating?

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A typical specification is broken down into 3 parts:
Part 1 – General
Part 2 – Products
Part 3 – Execution

In a typical specification for sprinkler pipe we often see something like this:
Part 2 - Products
2.2 Steel Pipe and Fittings
Schedule 40 Galvanized and Black steel pipe
Schedule 10 Black steel in pipe NPS 2.5 and larger

Part 3 - Execution
3.12 Piping Schedule
NPS 2 and smaller - Schedule 40 black steel
NPS 2-1/2 and larger - Schedule 40 black steel

When Part 2 and Part 3 of the same spec contradict one another, which part rules?

I know the answer is to write an RFI, but we often don’t get an answer prior to bid time.

Also, what is the thought process of the EOR for providing a spec like this in a bid document to begin with?

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When coming out of a pump room with underground feed which then connects to an underground loop with a bullhead tee, are isolation valves required on the bullhead tee?

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NFPA 13 provides allowed omissions for sprinklers in combustible concealed spaces where the entire cavity is filled "with non-combustible insulation". 

Is fiberglass the only non-combustible insulation? Is blown-in insulation considered to be non-combustible, or does it depend on the type of blown-in?

Just curious if there was helpful literature so that we knew what to recommend or look for when we come across these scenarios. Thanks in advance.

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When we run hydrant flow tests, we usually use both 2-1/2" side-outlets of a typical dry fire hydrant. We hook up one, threaded, swivel 45-elbow on each side to divert water in a direction that won't destroy anything.

What is the appropriate Coefficient of Discharge when measuring the pitot on the centerline of the elbow?

Traditionally flowing straight out of the side outlet of a hydrant, NFPA 291 gives three Coefficients (0.90, 0.80, and 0.70) based on how the outlet projects into the barrel. NFPA 291 also states that a coefficient of 0.85 is suggested for stream straighteners, unless the coefficient of the tube is known.

Is there a known Coefficient for a single 45-degree elbow?

Any help is greatly appreciated.

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When determining the most hydraulically remote area in a building, what takes precedent - the flow, or the pressure required?

In other words, when comparing two remote areas which are very similar, which would actually be considered the "true" remote area - an area with high volume and low pressure, or an area with low volume and high pressure?

I am inclined to say that flow supersedes pressure, but since "hydraulic" deals with the relationship between the two, I'm not 100% confident. Thanks in advance.

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Does code allow the drilling of load-bearing beam in multi-family residential buildings, for the purpose of running sprinkler pipe through it?

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NFPA 20 specifies a minimum size for suction pipe before a fire pump, to reduce the water velocity and avoid cavitation (among other things). NFPA 20 states that this only applies to 10-pipe diameters of length before the fire pump.

We have a very long run from the backflow preventer at the service entry and the fire pump room. Hydraulically, this long run works with a long 4-inch feed, which would then upsize to 6-inch right before the 450 gpm pump for the 10-pipe diameters.

My question is, am I allowed to drop the main size between the backflow and the fire pump? 

Hydraulically I don't see why not, we're not dipping below 20 psi anywhere on the system and we appear to meet code. Intuitively I've never dropped pipe size to pick it back up, but this situation with the pump feels a little different. This is above a multi-family unit, so 6-inch steel is nearly impossible to fit within short open-web joists and would be a major issue for the building owner if we had to drop a soffit.

​Thanks in advance for your take!

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We are getting a plumbing department reviewer's comment that the combined sprinkler/domestic water service cannot exceed a flow of 5 feet per second.

Their justification is that flow above 5 ft/s will negatively impact the "coating" on the inner surface of the copper pipe.

I've never heard of such a concern, and 5 ft/s is far slower than the hydraulic calculations can support. This is for small diameter services on an NFPA 13R project that is 3 stories in height.

The difference in tap fees between a 2-inch combined service (with an automatic domestic shutoff in this case) and a 3-inch ductile iron is at least ten thousand to the owner.

Is there some truth or justification to limit fire sprinkler flow to 5 ft/s on copper pipe?

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Are sprinklers within NFPA 13R required to be quick-response, or can they be standard response residential sprinklers?

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I have a 20-ft x 30-ft exterior projection that was initially supposed to be open to the sky. The builder made it open on two sides at the bottom with a 12-ft lid. The construction above goes to the roof and is concealed with no access from inside or outside, and it all is of non-combustible steel beams and joists with metal siding.

The million dollar question - sprinklers above and/or below? Or nothing at all?

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I'll preface this that I'm not a engineer. There is 17-foot storage with an existing sprinkler design of 0.20 / 1,500 sqft.

Based on NFPA 13, I believe we would need 0.21 / 2,000 sqft for a Class II commodity (non-encapsulated rack storage).

How would you recommend going about increasing both the remote area size and the density on an existing system?

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NFPA 13 Section 20.6.6.3:
"Early suppression fast-response (ESFR) sprinklers shall not be used in buildings with automatic heat or smoke vents unless the vents use a high-temperature rated, standard-response operating mechanism."

ESFR sprinklers are designed to act fast and suppress the fire, the inclusion of a roof vent that opens up before the sprinkler activates could severely impact sprinkler activation both in terms of timing and location (as the moving smoke could activate a more remote sprinkler). If automatic roof vents are present, they should have a high-temperature rated standard-response operating mechanism to ensure that the sprinkler activates before the vent opens up.

Based on the above, am I correct to interpret smoke venting is not required with ESFR systems?

How do I go about handling smoke or heat vents with ESFR, or are they not necessary to begin with?

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Are manual pull stations required to have any specific level of illumination at all times provided by emergency lighting?

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We have a project with a concrete planter wall near the edge of the sidewalk. The top of the planter is 32-inches above the sidewalk.

The architect would like the FDC on the planter wall, but a siamese-type would project too far into the sidewalk so he wants a flush FDC.

A standard brass FDC body with clappers would be buried under several feet of dirt so it would make sense to use spigots with clappers - but they would also be threading into a body/manifold that needs to be buried. Our concerns are replacement/repairs on the clappers; corrosion, and sealing around two penetrations through planters while still being able to repair/replace spigots.

We're also considering a 'sidewalk siamese' setup just inside planter wall, but 18-inches above top of planter puts them above 48-inches above sidewalk. I think this is best option but would required fire department permission and the architect is pushing for flush on the planter wall.

Is a flush fire department connection even an option here?

Are we being overly concerned with corrosion and/or maintenance issues on these buried parts?

Thanks in advance for suggestions for dealing with these issues.

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We are designing a warehouse which has a system demand of about 150 psi at 2,000 gpm.

There is an existing facility with a 150 psi @ 1,000 gpm rated pump installed approximately 1/4-mile (350 m) from the warehouse. We are planning to add a new 150 psi pump at 1,000 gpm near the warehouse roughly 65-feet (20 m) from it. 

Is there any code limitation we might hit to serve one building with two separate pumping stations installed remote from each other?

How would you recommend we set the pump operation sequence for the two pump rooms?

Each pump room will have an electric, diesel, and jockey pump. Thanks in advance.

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For a smoke control stair pressurization system designed in accordance with IBC 909 and IMC 513, does the code require a duct smoke detector on the supply fan?

Does the installation of a smoke damper at the stairway boundary factor into this requirement? (i.e. IBC 717.3.3.2 requires a detector within 5 feet of a smoke damper). Normally this motorized smoke damper is closed and then automatically opens upon activation of a specific fire alarm signal.

NFPA 92 6.4.6.2 does require a duct detector on the stair pressurization supply fan; however, I'm unaware of a similar requirement in IBC/IMC. NFPA's intent is to detect smoke on the air supply and shut down the unit before smoke compromises the stairway.

For elevator hoistways that require smoke control, IBC 909.21.4.2 states to provide a detector. I would have expected a general statement in IBC 909.12 with the same intention as NFPA 92; however, I do not see a similar requirement in the IBC/IMC for stairways.

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I am doing an evaluation of a water supply for a fire sprinkler system. The system is an ordinary hazard wet pipe fire sprinkler system. It was designed as a pipe schedule system. Table 19.3.2.1 of NFPA 13 – 2019 Edition gives the water supply requirements for Pipe Schedule sprinkler systems.

Based on our buildings construction the table requires that for Ordinary Hazard we have a 1,500 gpm flow with a residual pressure of 20 psi. Section 19.3.2.6.1 then states, “The residual pressure requirement of Table 19.3.2.1 shall be met at the elevation of the highest sprinkler.”

My understanding of this requirement is that if I have a pipe schedule system where the highest sprinkler head is 20 feet above the finished floor which equates to roughly 8.7 psi of head I would need to have a water supply that provides a minimum of 28.7 psig residual water pressure flowing 1,500 gpm to the base of the riser to meet the requirement.

Am I calculating the required residual pressure correctly?

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Is a two way communication system required when an elevator is installed (only for convenience) but is NOT required or designed to be part of the accessible means of egress - assuming none of the exceptions in 1009.8 apply?

Refer to CBC 1009.8: "A two-way communication system complying with Sections 1009.8.1 and 1009.8.2 shall be provided at the landing serving each elevator or bank of elevators on each accessible floor that is one or more stories above or below the level of exit discharge."

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We want to take a moment and thank all of our contributors, including our Top Contributors to the Forum for May 2021. Your feedback and willingness to share best practices is what makes this industry great. Top contributors for May are:

I have inherited a totally fun project, a R-2 III-B multifamily residential building at 27,300 sqft per story, three stories total. I'm on the architect side. 

Our mechanical engineer did a 61G (Florida fire suppression analysis) and designed the central lobby to be under NFPA 13 and the rest of the building NFPA 13R. I immediately thought where are the area separation firewalls, because we are over our allowable area for a III-B. The building is in construction, trusses have been set.

I was told that you can do an area increase in the hydraulic calculations, one with the NFPA 13 portion of the building and one with NFPA 13R add them together and get your increase. I'm calling BS because I cannot find this in the code anywhere, but supposedly this is coming from a FP consultant.

Any clues on the location of this allowance in code?

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