We have a Type II-B construction mostly light-hazard building with drop ceilings throughout. The plenum is not sprinkler protected. Walls go to either the ceiling or roof deck, depending upon the use of the space (ie: conference rooms have full-height walls for acoustics).

There is a closet which does not have a ceiling, and its' walls do not go to deck.

Does this opening invalidate the elimination of sprinklers in the plenum from NFPA 13 (2013/2016) Section 8.15.1.2.2 for non-combustible and limited-combustible spaces?

Would posting signage saying no combustible storage is permitted in lieu of extending the walls work instead of installing a ceiling?

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Is there a recommended maximum distance between the Fire Department Connection (FDC) and check valve?

NFPA 13 does not include a required maximum distance between the check valve and the FDC. I understand the intent is to reduce the length of non-pressurized pipe. My project includes a warehouse with a free-standing FDC located about 125-feet from the building.

Is it best to locate the check valve indoors, where it can be easily inspected and maintained, or, located underground, closer to the FDC where it would be buried?

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Our fire water demand capacity is 60,000 gallons, but our current water tank storage capacity is 30,000 gallons. We don't have any space near our current fire water storage tank. 

Is it possible to make another (second) tank with a capacity of 30,000 gallons and connect it to the old tank through pipe?

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Is a pumper truck from the fire department required to do standpipe flow testing?

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A special thank you to the top contributors for this past month!

Can the ceiling pocked omission rules outlined in NFPA 13 for standard spray pendents and uprights be applied to standard spray sidewalls?

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Has anyone come across a dual riser (dual-feed) sprinkler system in an office tower, with only a single inspector's test?

What is the proper method of testing each flow switch?

In most cases, only the flow switch nearest the inspector's test will operate in a timely manner. Some inspectors will isolate and test, others believe the system should be tested under normal conditions with both control valves open.

Is the deficiency the lack of a second test connection, or that the flow switch doesn't operate within 90 seconds (or even 5 minutes)? Alternatively, is there no deficiency at all?

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Is there a method to use a main drain test to calculate the hydraulic curve at the riser itself?

I haven't done it myself, but using a static pressure at the riser, with a residual pressure at the riser, and then to gather the flow a pitot reading on the main drain discharge to measure how much flow?

If the flow discharge outside was greater than the demand of the system, conceivably a hydraulic calculation could be made with the riser as the source point, and with more accuracy than a hydrant flow test somewhere near the site.

Obviously if a backflow test header or hose valve were supplied, a higher flow could be obtained with a better curve.

I heard this mentioned recently so it's just theory to me, but for small remodels having a setup like this could be far simpler (and potentially more accurate) to know the available water supply at the system.

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In our area, wet standpipe/sprinkler pipe running through unheated parking garages always gets heat tracing and insulation. 

On this current project, the general contractor wants us to run a 4-inch main as high as possible to a 7.5-inch thick post-tensioned concrete deck that has a heated space above it and a 24 deg F 1% design temperature below in the garage. They're looping 14-inches of batt fiberglass with a plastic barrier below it creating an envelope around the pipe.

The general contractor is questioning whether the heat tracing is needed. We've got plenty of experience 'tenting' sprinkler pipe in attics but never under concrete. I've suggested they hire a mechanical engineer to do the calculations.

Does anyone have experience with this situation?

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Is anyone having problems with steel pipe corrosion after using the older glycerin?

Three year old condominium complex was an NFPA 13R job. About 75% of the pipe is CPVC with exposed basements installed in steel. We hydo-tested four of the buildings in the winter with the glycerin before the buildings had heat so the builder can insulate and sheetrock. We drained out what we could but did not pull any heads in the basement. We didn't think leaving some trapped glycerin in the steel basement piping would be anything to be concerned about.

The basements have developed pin hole leaks and the odor when draining is putrid! I saw the new UL-listed (Freezemaster) antifreeze states, "includes a corrosion inhibitor package".

Any help/advice is greatly appreciated in stopping this attack on the pipe.

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I get asked by building owners somewhat frequently - what is the required clearance from a sprinkler?

I understand most typical ordinary storage/miscellaneous storage/office/standard spray sprinklers the clearance is 18-inches.

I also understand ESFR requires 36-inch minimum. I'm trying to understand the big picture and not misspeak. 

What about other sprinklers, like CMDA, CMSA? Is there a rule of thumb across the board?

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Does anyone have recommendations for who would perform inspection, testing & maintenance  (ITM) on deflagration vents under NFPA 68?

My company is having trouble finding a reputable organization that will take it on. The supplier of the chemical explosion prevention system with has turned down the work. There is a push from some to let our own maintenance handle it, per the checklist in the annex, but I feel that a group with this expertise would be a better fit. Thanks in advance.

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Having trouble getting a good feel for fire sprinkler design criteria for compact, mobile storage shelves. These contain Class I-IV commodities. As I understand it, NFPA 13 only covers light hazard for compact shelving.

The metal shelves have a height of 8-feet, the ceiling height is 26-feet. The room is 3,000 sqft, and the shelves have a footprint within that space of 21 x 30 feet. Any help is appreciated. 

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We have a four-story project that uses NFPA 13R - 2016 Edition. There are balconies with wood structure that are getting sprinkler protection. The building is in a cold climate.

I'm trying to figure out how to correctly incorporate these balcony sprinklers in the hydraulic calculations while still being efficient in the sprinkler design (there's no fire pump on this and poor city supply).

As I understand it in NFPA 13R, my options are:

(1) NFPA 13R for Dwelling Unit Calculation: use dry-sidewall residential sprinklers (Reliable and Tyco have some) for the balcony. This would then be a 0.05 gpm/sqft calculation over a compartment, up to four sprinklers. 

(2) NFPA 13R for Outside of Dwelling Unit: use dry-sidewall quick response sprinkler for balcony. This would be a 0.10 gpm/sqft calculation for four adjacent sprinklers. The inside sprinklers could still be 0.05 gpm/sqft (per 13R), but the balcony sprinklers need to be 0.10 gpm/sqft (per 13R 7.2.2, 7.2.3).

(3) If the balcony is under 500 sqft and meets a string of conditions, then dry-sidewall quick response sprinklers for the balcony can be for the compartment, up to four sprinklers (per 13R 7.2.3.1). We don't meet this here, because there are large glass slider doors over 50 sqft.

Are there other options here, or is my approach for the first two options appropriate? I could very well be overthinking this. Thanks in advance.

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We are designing a clean agent system for electrical rooms located within a high-rise building. We are proposing having dedicated clean agent releasing control panels for the electrical rooms, and a separate building Fire Alarm Control Panel.

Is it mandatory to connect fire/smoke dampers (and other shutdown devices) in the electrical room with the clean agent releasing panel, or can these be connected to the building fire alarm system?

Thanks in advance.

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We have a 40-foot tall steel construction building, with lumber strapped and stacked, stored in 20-foot high solid piles.

The building is unheated. The building owner has been told by another fire sprinkler contractor that this will require ESFR sprinklers. The owner would prefer a dry pipe system.

We have researched NFPA 13, 2019 edition. It looks as if Chapters 20 and 21 will allow a dry pipe system for this application using CMDA sprinklers.

Anyone else have experience with a scenario like this? What path would you recommend?

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We have a small project (13,800 sqft total) which is a four-story, all residential apartment building, using mostly CPVC pipe. The system is under NFPA 13R.

The city supply is very poor, so we will have a fire pump that meets NFPA 20 (as is required by 13R). The pump is an 8-HP, 70 PSI at 75 GPM.

Is a jockey pump necessary with such a small fire pump?

Normally, for our large commercial NFPA 13 projects, a jockey pump is not even a discussion because we don't want the main fire pump (500 - 1,500 gpm) cycling on just to support system maintenance pressure.

For such a small project with a significantly smaller fire pump, is there any harm in not providing a jockey pump?

The question is not based on cost - the pump room is microscopic and we're already having trouble fitting in all the equipment and controllers as is.

Appreciate you all - thanks in advance.

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This question pertains to hydraulic calculations at the supply and sprinkler sides of a deluge system:

Our example using rough numbers; the deluge system requires 4,000 gpm based on density requirements through the building. This is the system demand.

Now suppose you have a strong water supply. The water supply actually provides 8,000 gpm based on main capacity testing. This is the system supply.

Now my question is, the pipe is wet up to the deluge valve. There is about 50-feet between the deluge valve and the hazard. It is understood that the system demand is 4,000 gpm, but within the pipe network, is it necessary to size the pipe for a deluge system based on 8,000 gpm on the supply side?

Until the water begins discharging through the deluge nozzles, the 8,000 gpm will be surging through the pipe network to reach the nozzles, correct?

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Is there a minimum distance clearance required or recommended from the fire sprinkler and the top of a stacked washer dryer in small closet?

What is the reason for the clearance needed?

I heard that 4” is needed for the clearance rather than the standard 18” in a public area.

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I am building out a space that has been vacant for multiple years. The space has a hydraulic elevator that travels 1 floor. There is a sub that is ushering the elevator contractor through the certificate milestone with all the adjacent trades.

He has proposed to change out the Class III-B hydraulic fluid with a Hydro-Safe or equivalent non-combustible fluid in order to work around the NFPA 13 requirement for a pit sprinkler and pit detection to be installed.

My question is, does swapping the petrol-based fluid to a bio-equivalent have any long-term effects on the pump, pistol, seals, gaskets, etc.?

Also, how do I make sure this is the fluid that remains in use for the life of the certificate?

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We have a project that includes a 3,500 sqft unheated loading dock. We're in the initial design stages of the project.

Based on your experience would you recommend we specify a heat trace or dry pipe sprinkler system for the loading dock?

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A special thank you to those who helped bring in the new year with great feedback and discussion. Here's the top ten commenters for January 2021:

We have a project where the Authority Having Jurisdiction (AHJ) is requiring zone control valves and dedicated pipe from the standpipe to any IT rooms and sprinklers in elevator shafts.

As a result, we have three zone controls for each floor: (1) the floor sprinkler system, (2) IT rooms, and (3) any sprinklers in elevator shafts.

Is there a code or standard basis for this requirement, or would it be specific to the AHJ?

We're doing the work either way for this project since the AHJ is requiring it, but I would like to know for future projects. Thanks in advance.

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I was wondering if maybe there are some calculators or wizards that guide a selection of CMDA sprinklers for storage applications.

We work with multiple standards (Vds, EN, NFPA) and sometimes it takes a long time to find the right point on the curve out of NFPA 13. It would be great to have a tool to verify that density and multipliers were all chosen properly. Thanks in advance.

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