A small, wood-structure apartment complex is getting an NFPA 13R fire sprinkler system. Based on hydraulic calculations, the incoming water service only needs to be 2-inch, and the backflow can be as small as 1-1/2-inch. 

Many backflow preventers with indicating butterfly valves don't get down to the 1-1/2-inch size - rather many of the small backflows only have ball valves which I'm not sure can actually be supervised.

Are the valves on a backflow preventer for an NFPA 13R system required to be supervised? Is there ever a case where the backflows can use ball valves on an NFPA 13R system?

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Can multiple sprinkler systems be connected to a single air compressor/nitrogen generator?

NFPA 13 states that the 30-minute fill time would be based on the single largest system; so I'm assuming it's permitted and under this arrangement an air maintenance device would be needed to maintain the pressure in each system.

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For those experienced or well-versed in site utilities, what options for underground fire service pipe would you recommend? What is currently regarded as the most common options?

I understand ductile iron, concrete, plastic, copper and stainless steel are all permitted by NFPA 24.

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Working on a list of areas that should have or require drain connections for coordination with plumbing. Here's what I have:

(1) plumbing standpipe to accept main drain, where the main drain can't be routed to the outside,
(2) floor drains in riser room as good practice; required if there's a pump or RPZ-type backflow,
(3) plumbing standpipe to serve drainage from fire standpipes, where they can't be drained to the outside, and
(4) standpipe or floor drain for remote inspector's tests & drains, where they can't be drained to the outside.

What am I missing?

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For a horizontal manifold that contains multiple sprinkler systems, are check valves needed for each sprinkler system? In this case there are no standpipe systems in the building.

As I understand it, NFPA 13 only requires a check valve on the incoming fire department feed, but each of the different system risers have no requirement for a check valve.

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Is it necessary to provide a UL firestop for a sprinkler through a fire-rated partition?

I would think that since the penetrating item is a sprinkler that it would not require an actual UL firestop penetration, however I am having trouble finding a code reference to back up my thoughts. My scenario is a sidewall going to through a vertical double layer gypsum partition. 

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When is a relocation of an existing fire sprinkler permitted, and when must an existing sprinkler be removed and replaced with new?

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Without access to pricing differences, it can be difficult to make informed decisions when it comes to selecting fire pump controller starting methods. What is the magnitude of cost for each of the fire pump starting methods?

Specifically, I'm interested in Across-the-Line, Wye-Delta Open, Wye-Delta Closed, Soft-Starting and Variable Frequency Drives. Thanks in advance!

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Could someone explain the difference between the different labels of mains? I've heard the loose terms feed mains and cross mains but I can't seem to find anywhere these are defined. Any help is appreciated!

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Are flow meters for fire pump testing ever mandatory? Or are they only provided as a convenience to the owner so that fire pump testing does not have to discharge significant amounts of water to the outside?

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Was there ever a time when fire department connections were not required for fire sprinkler systems? I have some private campus buildings that don't have a fire department connection. Some have a single site connection that feed multiple buildings, but others don't appear to have one at all. Just curious if there was ever a code justification for this.

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What is the lowest demand pressure and flow you've come across for an ESFR system? 

Looking big-picture at owner storage options early in a project (when we might have an idea on available pressure but don't yet have a plan to work from), the minimum flow and pressure we've come across as a minimum was 73 psi at 1,450 gpm. It was using (12) K25.2 sprinklers at 15 psi (minimum storage heights and a 250 gpm hose allowance). If we don't even have this supply, I typically anticipate a fire pump.

Have you seen any demands lower than this?

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Have a small five-story restaurant and apartment building (each floor level is only 3,000 sqft), and it's under NFPA 13-2010. Is each floor level of the sprinkler system required to have it's own isolation valve and flow switch?

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What closeout documents should contractors supply at the end of a fire sprinkler installation?

​The ones we typically expect to see are (1) as-builts, (2) test certificate for aboveground pipe, (3) test certificate for underground pipe, and then (4) warranty and product data for the owner. Are we missing anything?

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Where does the requirement for a post-indicating valve originate? If I only have a sprinkler system, is a post-indicating valve required?

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Would you consider a kitchen with only an oven/stovetop unit in a primary residential building to be considered Light or Ordinary Hazard for sprinkler protection? 

NFPA 13 annex material states that commercial kitchens should be considered OH1, while "Residential" areas are Light Hazard. Interested in others' input on this.

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When a backflow preventer needs to be replaced, can the two isolation valves remain in place, closed, and only the center body of the backflow be inserted in-between these isolation valves?

Would this violate the listing on the assembly if it's a one-for-one replacement?

If the backflow is listed as an entire assembly, then it seems as though an additional isolation valve on the supply-side of the backflow preventer would often be needed to shut off the system just in order to replace the backflow preventer.

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What is the maximum throw for a horizontal sidewall sprinkler? Just looking for a typical extended coverage sprinkler, not a dry-type.

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Many fire pump arrangements I've seen include flanged fittings and pipe connections on the suction side of the fire pump. Is there a requirement for this?

Are grooved connections allowed for pipes and fittings on the suction side of the pump assembly?

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My company has recently re-evaluated how we take measurements onsite in the hope that we can find better/faster solutions than running tape measures to nearby structure. We create shop/installation drawings, to precision in measuring parts of existing systems is important.

What do you use when on job sites? Tape? Laser Measure? 360 cameras? Has anyone had any luck using laser scanners or photometrics for measurements? 

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A fire marshal is requesting a wall hydrant on the backside of a project where there is limited access. Is there a prescriptive flow that needs to be calculated at this location?

This project is considered a high-rise (8 stories) and does have a fire pump. He has already requested there be 100 psi available at the wall hydrant.

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Have a dry manual standpipe system that is going to be retrofit along exterior stairs in the southern US. Is there any requirement that would prevent the standpipe from being interconnected underground (not under the building)?

I understand there's difficulties with drainage and access for future repairs, but as a last option is it even permissible by code? 

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I've heard that sprinkler frame arms are typically aligned with the pipe which they're connected. I commonly see this for uprights, but how often is this true for pendents?

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Is the discharge side of a fire pump required to step up to a larger pipe size on the discharge flange of the fire pump? Inspected a pump where there was a flowmeter welded on flanged pipe which was the same size as the discharge flange of the fire pump.

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