NFPA 13 lists requirements for calculations showing that hangers must be designed to support the weight of water-filled pipe plus 250 lb (115 kg) at each point of piping support (NFPA 13 9.1.1.2 of 2016 Edition).

When are these calculations necessary?

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What sprinkler type or finish would you recommend for a highly corrosive area? In this case I'm working on a pool equipment room.

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Does the "small room rule" apply to sidewall sprinklers?

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From a sprinkler contractor in the UK - We have a British Standard BS 9251 which is based (loosely) on your NFPA 13 D/R for the use in houses, flats and care homes and so on.  One area which is very grey to us and not included in the design standard is the distance from obstructions such a pendant lampshade which lower than the ceiling or a smoke detector or emergency light fitting.  

I know most contractors are using 300mm (1 ft) as a minimum from a pendant drop light fitting but then you ask them why no one can tell you.  for other obstruction such as a smoke detector many any using 4 times the depth as a method.

For beams and larger continuous obstructions, it's much easier as most just use a bean rule in EN BS 12845 (our equivalent NFPA 13).

I would be very interested in understanding the approach which you take for such things and very much looking forward to your assistance.

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Had a  quick question regarding design of thrust blocks for underground FDC / fire water supply.   In your experience is that design typically a civil designer’s responsibility or the responsibility of the fire sprinkler sub?

I have a project where both parties are saying they do not do this design – the sprinkler sub says their design begins at the flanges in the riser room.  I have an earthwork subcontractor doing the physical installation of the FDC and fire water pipes outside leading into the riser room. Would thrust blocking details then need to be calc’ed and detailed by the civil engineer? 

I’d appreciate knowing what your experience has been!

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I've come across several retail projects where there will be a "closet" that is just solid shelves about 18-24 inches deep and about four or five shelves tall, with a mirror across the front that acts as a door. It's certainly possible to provide a sprinkler outside of the closet and protect to the back of the hazard, but is this approach allowed?

To me it doesn't seem practical to provide a sprinkler at the top inside this shallow unit just as we wouldn't provide a sprinkler within the inside of cabinetry. If anything, the multiple solid shelves could prevent heat from collecting at the top and water from effectively reaching the bottom, although the door could also prevent discharge from reaching the bottom. Curious how others would approach these situations.

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I've had the request multiple times from architects to provide closely spaced sprinklers near interior windows to provide the equivalent of a 1-hour wall. 

The only support I see for such an arrangement in the International Building Code or in NFPA 13 for glass is specific to the "Enclosure of Atriums," Section 404.5 (2003-2009 Editions) or 404.6 (2013-2015 Editions).

If someone is looking to provide the equivalent of a 1-hour wall, with glass, that is not a part of an atrium enclosure, then are the only options to provide rated glass or the Tyco WS Window Sprinkler?

I sense a lot of confusion on this topic from architects, whom I guess see other project arrangements and just assume they're standard closely-spaced sprinklers.

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Is a sprinkler ever not required in an electrical room? We typically provide sprinklers in all electrical rooms, but are being asked specifically if we can omit one on a project.

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A foam system is being used to protect for spilled methanol within a dike of a tank 1,120 square meters (12,055 sqft). What foam proportion would be recommended?

Is there an advantage between a balance pressure pump proportioning system or an in-line balance pressure pump proportioning system?

The system is being designed under NFPA 11, 16, and 30.

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If a glass face of a shower door goes up adjacent to the ceiling (and the bathroom is not excluded from sprinkler protection based on size) then would the shower itself need sprinkler protection?

Based on the proximity of the shower's glass door to the ceiling it looks like it would be a floor mounted obstruction, per NFPA 13.

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Have a project that requires the sprinkler system to be zoned by the areas with active smoke control. Each floor of the highrise is approximately 12,000 sqft is to be divided into two zones. I intend to have multiple floor control risers (valve, check valve, flow switch, pressure gauge, inspector's test & drain) for each smoke control zone. Is there any less costly way of accomplishing this?

It has been suggested that multiple flow switches can be placed on the same system with different retard settings so that the fire alarm system can identify where the water is flowing, but I don't have experience with this option.

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I have a question regarding performing or checking hydraulic calcs for a pressure tank supplied system in a retrofit application.

As an example, suppose our system is located 5 floors below the existing pressure tank for a high rise building in New York City (NYC). The tank was designed and installed under prior codes and utilized the pipe schedule methods. We may have 2 tanks connected that are 9,000 total gallons capacity each with 1/3 air and 2/3 water pressurized at 75 psi (the initial pressure) at the tank.

Our connection to the sprinkler riser being 5 floors down now has 75 psi plus the pressure gained by gravity (5 psi per floor typical NYC arrangement) equaling 100 psi static available.

The jurisdiction now requires all systems to be hydraulically calculated. The calculation are done to the point of connection to the riser and not all the way back to the water source (NYC quirk) and no hose demand.

The contractor provides a calculation stating that the system demand is below the 100 psi (95 psi residual) and less than 400 gpm (light hazard occupancy 30 minute supply), and claims it works. We’ve argued that as the tank drains, the air-to-water ratio changes, therefore the pressure available at the end of the 30 minutes is not the same as initial tank pressure.

Using the formula given in the Annex of NFPA 13, we can solve for what a system demand should be given the existing initial conditions of the tank plus the pressure gained by gravity and say that as long as the calculated system is less than that pressure, the system is acceptable. But is that a correct assumption?

I want to give them all the correct procedure, methodology and theories behind this subject.

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A project that has evidence storage will have a new fire sprinkler system. The storage is anticipated to be solid back-to-back shelves no more than about 8 feet in height, but will hold crime evidence which could and will likely include firearms. What sprinkler design density is required for this area?

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A retrofit project has very low floor-to-floor heights where we need to install floor control assemblies within the stairwells. Is there a minimum "head height" for the pipe that it needs to be installed above the floor if the pipe isn't against a wall?

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When are pressure relief valves required for fire pumps, and what is their intended purpose? There's a wide variety of pump arrangements and many don't include pressure relief valves.

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We're in the process of reviewing our specifications against industry markers and I'm interested in comparing major differences in owner-driven specifications (not NFPA, FM, XL GAPS, or other insurance standards). What clients do others work with that they find represent good practice for the industry?

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Have a project which requires very tight coordination between sprinkler and ductwork. The ductwork will be lined with insulation which could come in contact with the black steel fire sprinkler pipe. Is there a minimum clearance required that wouldn't permit this contact by code?

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A 500 sqft rated liquid storage room is to be created within a fully-sprinklered 200,000 sqft warehouse. How many 55 gallon drums of Class IIIB liquid (flashpoint above 200 deg F) can be stored within this room?
     a. 18 containers
     b. 36 containers
     c. 87 containers
     d. 90 containers

Solution | Posted 10/23/18

​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 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 10/22/18

​Fire sprinkler system design has been based upon all of the following except:
     a. Empirical flow and pressure loss calculations
     b. Application of experienced judgement and reasoning
     c. Mathematical suppression modeling
     d. Evolutionary changes based on fire loss

Solution | Posted 10/12/18

A project site is connected to a water tank through an equivalent 650 feet of 6-inch schedule 10 pipe (c-factor of 140). If the water tank is 165 feet above the project site, the fire flow available at the project site is most nearly:
     a. 1,300 gpm
     b. 2,100 gpm
     c. 2,400 gpm
     d. 8,700 gpm

Solution | Posted 10/10/18

Where can I find presentations or references on the differences between NFPA 13-2016 and 2019 editions?

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​A fire department connection may be installed by any of the following arrangments except:
     a. Between the supply control valve and the system control valves for multiple sprinkler systems
     b. Attached to underground system piping, between the supply control valve (at the main tap) and the system control valves (inside the building)
     c. Attached to main pipe on a system (on the system side of the system control valve) for a single wet system
     d. Attached to the main service between the utility tap and the entry into a fire pump room

Solution | Posted 10/09/18

The static discharge head equals the sum of all of the following except:
a. Total static head
b. Discharge system losses
c. Suction system losses
d. Net suction head

Solution | Posted 10/05/18

An warehouse facility is seeking to store cartoned Level 3 aerosol products on pallets. If the storage height is 10 feet in height with a 23 foot ceiling, what minimum k-factor must be provided for the ceiling-level sprinklers protecting this area?
a. K-8.0
b. K-11.2
c. K-14.0
d. K-16.8

Solution | Posted 10/01/18