I have a client who owns multiple assisted living facilities. It's residential construction with attic insulation on the roof trusses' bottom chord, and louvered gable ends with ridge vents.

They have existing wet pipe sprinkler systems in the attic and have experienced busted sprinkler lines in the past. They want to heat the attics to prevent this with electric heaters.

I have done the heat loss calculations and have determined the heating load would be more than their current electrical service can support. The only options I see available are heat trace, anti-freeze, or conversion to a dry system. Anti-freeze with UL-listed anti-freeze was my first thought, but it looks like a backflow preventer would have to be added.

Does anyone have experience with this and/or have recommendations on how to address this?

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Is there any way to install sidewall sprinklers in a room with sloped ceilings?

Say you had a rectangular room with a ceiling attached directly to the underside of a traditional gable roof with a high ridge peak in the middle. Concealed pendent ceiling sprinklers are often not possible ​because the space above the ceiling is completely filled with insulation.

Can you do sidewalls on the vertical walls near the ceiling high point to protect the room?

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Can you use a different k-factor for sprinklers in a duct and plenum versus the k-factor for the booth sprinklers in a paint spray booth?

I was told I could not use different k-factors to calculate the hazard. Thanks in advance.

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I'm designing a dry system feeding an area of about 600 sqft. It's a Light Hazard area, so the design criteria is just 0.10 gpm/sqft over 1,500 sqft.

Should the design area include the entire area, or could I just calculate the 5 most demanding sprinklers?

Per NFPA 13 2016, Section 11.2.3.2.3.2 under the quick response sprinkler section states, "The number of sprinklers in the design area shall never be less than five."

The section above that does state that the area of operation can be reduced, but that only applies to a wet pipe system, amongst a few other points. Of course, this is a dry system, so I don't believe the reduction can be used for this situation.

How should this design area be calculated?

​Thanks in advance.

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I'm trying to understand how (if) Section 7.2.3.8 of NFPA 13, 2016 Edition could be applied.

Dry pipe systems with water delivery times other than 7.2.3.2, 7.2.3.5, and 7.2.3.7 shall be acceptable where listed by a nationally recognized testing laboratory.

When would this come into play?
​
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Where is the code section that states the numbers (calcs) on the supply side shall be greater than the numbers at the base of riser (system side)?
 
Does the code address this with a code section?

​Thanks in advance.

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We have a project that is a retail tire store. In the back, there is a Tire Storage Room with a mezzanine of open grate flooring that takes up the majority of the floor plan for the room. The top of the open grate flooring is roughly 10-ft and the top of the roof decking is about 11-ft above the mezzanine.

Tires are stored on racks on both levels.

I think that CMDA sprinklers are the only real solution here because of the clearance to storage requirements. But, if we tried to use CMDA or ESFR, the owner would have little usable storage height.

Can anyone think of another good solution?

We have FP plans as part of the bid documents, and they specified something that won't work, so we kicked back an RFI for clarity, but we thought it would make good discussion here.

Can you have two fire sprinkler systems in one area?

A place is looking to charge a fleet of electric vans in an enclosed parking structure. The building already has a wet system designed for Ordinary Hazard Group 2. They want to put in a 16-zone extra-hazard (group 2) deluge system to work alongside the existing wet system.

​Has anyone heard of this before?

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If I have a fire tap that services multiple buildings, is it required to have a service valve outside the building on each line?

Does each building need to be capable of being isolated in case of service needs without interrupting others?

As it is, if one building needs work done to the #1 valve on the backflow then the other buildings will have to lose water during repair.

Thanks in advance.

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MeyerFire has a great thrust block calculator that appears to match NFPA 13’s annex/appendix exactly.
https://www.meyerfire.com/blog/a-new-thrust-block-calculator-part-i
 
How can the thrust block volume fit within the dimensions of the thrust block?
 
The default entries, for example, give a thrust block volume of 57.8 ft³ (NFPA 13 Equation A.6.6.1c), a base height of 2.2 ft, and a base width of 4.27 ft.  This meets the bearing area required by the equations.
 
NFPA 13, Figure A.6.6.1(b) gives the angle between the base of the thrust block and the pipe as 45°. This makes the thrust block a pyramid shape but ends with a pipe instead of coming to a tip. The Figure shows both vertical and horizontal angles as 45°, but that wouldn’t work unless the height and width are equal.  If 45° is the minimum angle, then the width of 4.27 ft would control the distance from the base of the pyramid to the pipe. If each side has a 45° angle, this distance would be half the width or 2.135 ft.  These dimensions can be used with the pyramid volume formula to give another method to check the thrust block volume.
 
The pyramid formula is V = L*W*H/3, which gives a volume of 6.7 ft³.  This is very different from the NFPA equation result.   Even if the thrust block was poured as a cube, its volume would be V = L*W*H, which is 20 ft³ -- still much smaller than the NFPA value. – I am counting the tip of the pyramid, which is part of the pipe, not the thrust block. It would be more accurate to exclude the tip, lowering the required volume slightly, but it would be harder to calculate.
 
If the pyramid were 57.8 ft³ with a bearing area of 2.2 ft by 4.27 ft, then it would need a distance from the pipe of 18 feet.
 
I think there is something wrong with Equation A.6.6.1c in NFPA 13.  It doesn’t make sense that it cancels the thrust force with the weight of the fill material. If you could use some incredibly dense fill material (pretend fantasy fill that is 8670 lb/ft³), then the thrust block volume would be 1 ft³ by that formula, but how is that small thrust block volume going to transfer the thrust forces onto a large enough soil surface? 

The weight of the thrust block material should not be related to calculating the volume of fill material required.
 
Another issue I see with the equation is that it is suddenly using T = P*A*sin(theta) while all previous formulas were using T = P*A*sin(theta/2). 

Why did the angle change for this formula?

Thanks in advance for any insight you could shed on the difference in volume versus shape with the NFPA formulas.

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I am working on a design for a wet sprinkler system in an industrial oven. This oven has steel mandrils with fiberglass strands coated in epoxy rolled through them, heated to 350 degrees. Then, they are rolled through another machine that blows ambient-temperature air onto the mandrils to cool them down. This process forms fiberglass/epoxy-reinforced conduits.

There are (3) total exhaust ducts, one penetrating the roof and two extending 5'-0" above the top of the machine and into the open building. No dipping, flow coating, or spraying happens in this machine. Strictly heating and cooling.

I am guided by NFPA 13's rules on ducts, but I don't believe NFPA 33's design criteria would apply here. I am also guided to NFPA 13 2022 9.3.8 and A9.3.8, but I am unclear on whether 15 psi is required at each head based on the wording.

My thinking is that a 0.2 over the whole oven would be the design criteria, protecting the hazard (OH2) in a non-FM building.

What are the code references for obstructions greater than 4 feet wide (ductwork) but located only 18" from the floor?

We have a mechanical room with several large ducts 5 ft wide x 3 ft tall. The ducts are only 18" from the bottom of the duct to the finished floor.

Additionally, there is a second level of a similar-sized duct that is mounted above, which leaves a 12" space between the top of the lower duct and the bottom of the upper duct.

Would we be required to install two levels of shadow protection under each duct, or are there provisions that allow sprinklers to be omitted if there is limited space below the duct?

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Our high-rise facility consists of apartments, condominiums, retail on the bottom floor, restaurant tenants on the top floor, and (3) levels of underground parking. We are 9 stories tall out of the ground.

They have great water pressure at the site with 140 static and 118 residual, flowing about 1,900 GPM, but with our floor-to-floor distances, I cannot get 100 PSI at the top of my standpipes. The building footprint is spread out, so I will need (8) standpipes to cover the hose lay inside the building (fully sprinklered). I'm assuming one 1,000 gpm pump will cover all the standpipe demand.

To complicate matters, this is in a seismic area D classification, and with it being a high rise, I am required to have a secondary on-site water supply. The intent was to install an underground tank to supply the fire pump or pumps, if necessary.

My thought was to supply water directly from the city main to the tank, and if there is ever a break in the city supply line, the pump would be served from water in the tank, which would have enough capacity to serve the facility for 30 minutes.

Is 30 minutes the duration I need?

What do you think about how I plan to serve the building? Would that meet the requirement for a secondary water supply?

Do I consider the standpipe demand when sizing the underground tank, or just the most demanding area of my sprinklers?

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