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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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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We have a building that used to be a business occupancy but the new occupant wants to now use the occupancy as a church (assembly).

The building is not sprinklered and has no fire alarm system. The new occupant load is 279 people.

The problem is the main entrance is on ground level but the second rear exit is below ground level to exit the building. Is the second rear exit below ground level acceptable?

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If a fire sprinkler systems is designed for "life safety" purposes, should not a primary and standby fire pump be provided? Why are standby pumps not required to improve reliability for these systems?

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We have a building with a double check backflow assembly on the suction side of a fire pump. Normally there is a minimum of 10 pipe diameters of vertical plane pipe just before the suction flange.

Is the double check backflow allowed within that distance?

Are there requirements for the backflow to have flanges vs. grooved connections?

A colleague said the control valve should be OS&Y rather than butterfly on the suction side only. Why would this be the case? I would assume the OS&Y would reduce turbulence better than a butterfly, but wouldn't the checks also cause turbulence?

Thanks in advance.

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I have an exhaust system serving a welding and metal fabrication lab at a school. They will utilize 70% ferrous metal and the remaining will be a mixture of stainless steel, coated steel and aluminum.

The largest duct diameter at the building exit is 30" round. The dust collector will be located on the exterior of the building and in a freezing environment.

Will I need to provide fire suppression within the ductwork both inside and outside as well as within the dust collector?

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​I am currently working on an existing high rise building that requires a fully automatic sprinkler system to be added and the AHJ is requiring a water tank to be added on the property to serve as a secondary supply.

There is no room for a secondary supply.

Can a pool be used to substitute a water storage tank that will supply the building through fire pumps?

What codes could back up this option?

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Is there a maximum all-thread rod length called out in NFPA 13?

This application isn't for seismic, but a general hanger for pipes 2-inch and under in diameter. Thanks.

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We are working on a project where a feed main is running through an unsprinklered space to get to a sprinklered area. I've heard that sprinkler pipe needs to be protected by sprinklers so we are trying to figure out if this is an actual requirement or not.

We are talking about putting uprights on the feed main in the unsprinklered area to protect the pipe but I can't find anything in NFPA 13 that actually requires the pipe to be protected.

Does anyone know if this is a requirement or not?

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When would you consider an obstruction no longer an obstruction, vertically below an ESFR sprinkler?

If the top of storage has to be 36" wouldn't 36" be the cut off? Or do the obstruction rules go the floor?

I have a warehouse that has 2 x 4 light fixtures which are 6'-0" below the roof deck, and am wondering whether these are considered obstructions. Thanks in advance.

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Regarding fire sprinkler system flushing of a wet-pipe gridded system; NFPA 13 Section 16.6.4 “All branch lines on gridded systems shall be arranged to facilitate flushing”.

We are doing a project which has more than 50 branches in a gridded system.

Do all these branch lines need to be provided with a flushing capability? How is this commonly achieved?

FM Global data sheets say to provide a small nipple between two flexible couplings, assuming removal of the nipple to flush the lines. Are there alternatives to this?

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I have a project with a typical compressed air dry sprinkler system in an unconditioned attic space (site is at 44 deg latitude). The system is 22 years old.

Site maintenance person reports that they've had issues with this system for at least 15 years. Frequent and repeated leaks, predominately pin holes in the mains. They try to repair before the system gets wet, although not always in time.

They recently replaced a 3 inch main and found that it was about 30% filled with sludge. Sludge was dark brown, almost clay like, sludge.

Any thoughts on how such a large volume of sludge can accumulate in a dry system? 

Thanks in advance.

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