Hope everyone is having a great week. We're wrapping up this week's Daily Forum with a poll for use of software for hydraulic calculations. Don't see the poll below? Vote here.

If you would like to see your question (or poll) posted, please send it in or email us at info@meyerfire.com. Thank you!
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I've taken technical writing courses and have experience working with MasterSpec, US Military specifications, vendor specifications, and various ownership standard specifications.

I'm giving an internal training to our younger staff and I'm particularly interested in opinions from contractors and vendors who regularly read a variety of specifications for bidding.

What advice would you give for those who write specifications? I'd be interested in helping train our staff as well as improve myself.

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For years on my code calls I have asked the Authority Having Jurisdiction what the maximum distance the nearest hydrant is allowed to be away from a building's fire department connection. I get answers that range from 50 feet to 400 feet or even more.

I was looking into the code basis behind this question, and the only applicable section that I found is the International Fire Code, Section 507.5.1.1 that addresses hydrant locations for standpipe systems:

"Buildings equipped with a standpipe system installed in accordance with Section 905 shall have a fire hydrant within 100 feet (30 480 mm) of the fire department connections. Exception: the distance shall be permitted to exceed 100 feet (30 480 mm) where approved by the fire code official."

Is there any relevant requirement for hydrants near fire department connections for sprinkler-only systems?

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Pressure Reducing Valve are commonly used to prevent excess pressure upon systems when supplies exceed the NFPA limit of 175 psi.

There has been much discussion regarding the 'application' of these valves when hydraulic calculations are being provided to the discharge of the PRV and determining the pressure margin available.

Currently, we have been instructed to calculate the system back to the PRV, use the PRV's friction loss calculator to determine friction loss through the valve and subtract that from the outlet setting to establish outlet pressure. This is then used as the available pressure at the outlet; minus the demand and you're left with the margin.

I'm not sure that I agree that the valves 'friction' loss need to be considered unless you are at a point where the PRV can no longer provide the set pressure (when the supply is unable to provide sufficient inlet pressure to overcome the internal friction loss).

Are there any 'papers' written for direction or other sources anyone might recommend?

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Amazon is selling fire sprinklers, escutcheons, and sprinkler guards. Some are UL Listed. But many are not listed for use together.

Because of the strict code requirements for installation and testing, is this appropriate marketing?

Who is liable for improper installation and system component failure? Who approves this?

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Have a project where the client is wanting fully-concealed sprinklers, but the project is insured under FM Global. FM does not approve any fully-concealed sprinklers as quick response.

However, under NFPA 13, light hazard spaces are required to have quick response sprinklers.

How do you normally address this conflict?

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​We're located in a seismic area where PT decks are to be considered cracked concrete for the purpose of hanging and bracing. We see a lot of the Dewalt Mini Undercuts and now the newer Hilti HDP-TZ inserts being used to hang up to 4" pipe from the concrete decks. The data sheets show them with pullouts of under 240lbs.

​How can these be used to hang ANY sprinkler pipe if the minimum required capacity of the hanger assembly is the weight of the water filled pipe plus 250lbs?

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Basic question but I don't know the history - why do we limit pipe to 21-foot lengths? Manufacturing limitation? Transportation? Just curious on the history there.

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NFPA 14 requires standpipes to be full flow tested for the acceptance testing.

Automatic standpipes are fairly straightforward to test, but how have you seen this applied for manual standpipes in mid-rise buildings?

Is this a worthwhile test that will uncover design/installation flaws?

Also, is there any compromised method to meet this requirement?

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In a residential dwelling unit of a high rise building, would a drum light fixture (7"h x 14"d) qualify as an obstruction?

It’s a concealed head in a residential unit of a senior living building.

The contractor – of course – doe not have exact dimensions because it wasn’t reflected on the plans and was added later as a lighting option and only caught by my inspectors during Rough-In. As it is installed, the head is a few inches from the fixture in some units and “a few feet” in others. They want to add a head on the other side of the light, approximately 3 feet -4 feet away citing NFPA 13 8.10.6.2.1.4.

I feel that the light, while an obstruction, doesn’t count as continuous nor does it meet the requirements of a baffle, so if they want to add another head it’d have to be at least 6 feet away to prevent cold solder.

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This question would be good for the seismic bracing experts in the group: NFPA 13 and ASCE/SEI 7 address the Component Response Modification Factor (Rp) as a ductility of the system. It comes into play when determining the seismic design force using the ASCE/SEI 7 method (not the simplified method used in NFPA 13).

NFPA 13 states several times that this factor (Rp) is 4.5 for steel systems (NFPA 13-2016 A.9.3.5.9.1 and E.3). The only mention of plastic pipe systems is in Annex E.3 where it states an Rp value of 4.5 for "high-or limited-deformability piping with joints made by threading, bonding, compression couplings, or grooved couplings", and an Rp value of 1.5 for "low-deformability piping such as cast iron and non-ductile plastics". Is a Response Modification Factor of 1.5 suitable for CPVC pipe?

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NFPA 13 (2016 Section 7.1.2 or 2019 Section 30.3.1) requires a relief valve on all wet pipe systems. The only exemption is where air reservoirs are installed to absorb pressure increases, then a relief valve isn't required.

This seems straightforward but I don't recall seeing independent relief valves on the far majority of the wet pipe systems I've come across. How is this requirement typically met from a design standpoint? Am I missing something or looking in the wrong place?

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If you have an open ceiling (both corridor and adjacent rooms), with a lot of ductwork and plumbing hugging the deck that may cause issues for sprinkler discharge, can you consider it obstructed construction and move the upright sprinkler 22" down from the deck to help avoid the obstructions? (Per NFPA 8.6.4.1.2)

No ceiling tile, ordinary hazard, not large beams either. 

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Is there ever a requirement to have additional valves on either side of a fire sprinkler backflow preventer assembly (which includes two vales already)?

My understanding is that if the center backflow body needs to be replaced, it can be replaced by closing the valves that are part of the assembly, removing the center body, and replacing it with the same model center body as the original backflow preventer. Correct me if I'm wrong, but I believe this still retains the listing of the backflow preventer.

Had a review comment for a project in Illinois that an additional OS&Y valve is required on either side of the backflow preventer, which is in addition to the ones provided with the backflow preventer assembly (Illinois Plumbing Code IPC 890.1130 g 2). To me this doesn't provide any benefit to the system, but only introduce additional repair/failure points and provides two more possible locations where the system could be put out of service.

Have you ever seen this before?

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If a light hazard room is 13 feet x 13 feet, and a k5.6 pendent sprinkler is located seven feet from two of the walls, what is the sprinkler area used for hydraulic calculations?

In short, to determine the minimum flow from a sprinkler in multiplying the area by the required density, is the actual area of the room used (13'-0" x 13'-0" = 169 sqft) or is it computed the same as the maximum area of coverage for a sprinkler by doubling the furthest distance from adjacent walls [(7'-0" x 2) x (7'-0" x 2) = 196 sqft)]?

For a room like this with a K5.6 sprinkler k-factor, it would make a difference between delivering 19.6 gpm to a room (0.1 gpm/sqft x 196 sqft) and 16.9 gpm to a room (0.1 gpm/sqft x 169 sqft).

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The other day there was a good discussion on pipe that can run within the open-webbing of steel joists.

Is there a good rule of thumb or any references to determine how long a pipe can be to fit within the joists?

I'm wondering if there's some tool or resource that says for 16" joists that has 2" web spaced at 4 feet, I can use only a 10.5 foot pipe length. It may not exist, just curious if it does already in some fashion.

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Concerning fire flow, you mentioned that the IFC is based on the ISO Method, how close are they and can you provide any more background on that?

If a building meets IFC, would you expect it score very well under an ISO evaluation?

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NFPA 13 requires closely spaced sprinklers with a draft curtain around unenclosed moving stairways, staircases, or similar unenclosed floor openings which are not large (20 feet or more across and 1000 sqft or greater), as an alternative to the enclosure of the vertical opening (NFPA 13 8.15.4.1 in 2016 and 9.3.5.1 in 2019).

This seems to jive with NFPA 101, but where does it come into play with the International Building Code?

As a sprinkler designer I want to be cognizant of situations where closely spaced sprinklers and draft curtains are necessary, but would they only surface as an AHJ-approved code alternative by IBC 104.11 (Alternative materials, design and methods)?

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For a flight simulator inside a larger building, what sprinkler density do you feel would be appropriate for this hazard?

The simulator will be its own contained unit, so the top will likely shield water spray from sprinklers above and prevent water penetration to the inside, much like a vehicle fire would in a parking garage.

NFPA 13 does not address simulators, nor does UFC 3-600-01 or FM Data Sheets (as far as I can tell). In my opinion the closest hazard I can gather would be vehicles in a parking garage which carry an Ordinary Hazard Group 1 designation under NFPA 13 (2016) 5.3.1 and A.5.3.1.

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A dry manual standpipe is being routed as a retrofit on the outside of a building. The dry standpipe will have short runs on top of the existing flat roof based on the layout and existing systems within the building.

What is the most prudent way to protect this pipe?

I'm concerned about direct exposure to the sun and rain. At a minimum we will have a couple coats of epoxy paint over primer, but I suspect that even the paint will wear down and required new coats at some point in the future.

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Still in the design phase for a new dry pipe fire sprinkler system retrofit into an existing attic space. Due to the existing arrangement of the building it may be significantly easier to route a portion of the system exposed to the outside. 

My only concern with doing so, along with ensuring that the exterior of the exposed pipe is well protected, would be the potential difference in temperature between a cooler outside and a potentially much warmer attic.

Would condensation not build-up when the cooler outside cools the pipe as it enters the warmer attic?

I may be overthinking this, but how best could I address potential condensation concerns in a scenario like this?

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What do you recommend as the best route when routing fire sprinkler branch pipe for projects with open-web joists?

Advantages (to me) to routing within joists can be higher ceiling elevations, potentially avoiding conflicts with ducts or other systems, and potentially allowing higher clearances below the pipe for vehicles or moving equipment.

Disadvantages (to me) seem to include the difficulty of getting the pipe up and into the joist (depending upon the length of the pipe and the opening size in joists), potentially mis-aligning joists that can't allow a straight run, and potentially running into solid girders if all of the structure isn't open-webbed.

What are your thoughts?

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A basic question from a non-ITM guy: is the hydrostatic 200 psi or 50 psi over working pressure test simply achieved by hooking up a mobile pump to the system and gauging for pressure loss and visual leakage?

I have not witnessed one of these myself, and wondered if a system design usually would incorporate an extra small outlet for this test or if it's just connected to a main end-cap or something similar.

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I was needing a little help validating the methodology for fire flow requirements in my city. They do not allow you to verify fire flow per a fire hydrant flow test.

Our city always uses hydraulic calculations (a hydraulic model) to determine acceptable flow in an area. However, in their hydraulic model they always assume that the water usage that day is 19,000,000 million gallons which was established by taking the highest usage in the history of our community of all time, which occurred in 2012 when we had 30 plus days of 100 degree weather of 18M gallons and adding a 1 Million to that. Our average daily usage in our community is around 10 to 11 million gallons per day.

Anyway, the local engineers say that methodology is consistent with the International Fire code. What are your thoughts? I would love to understand what the IFC requires.

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Residential single-family dwelling is getting an NFPA 13D sprinkler system with a pump and water storage tank. 

Is the test line required to be routed to the exterior, or can it be run back to the water storage tank? I've seen it both ways but don't see an applicable code section.

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