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Haven't come across this one before - are the horizontal pipes, both suction and/or discharge from a fire pump, required to be seismically braced?
We have seismic bracing required for the building and a review comment to assess bracing for the fire pump suction and discharge. NFPA 20 and 13 both don't seem to speak to it, but perhaps I am missing something. What is code required for seismic on these two runs? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
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We have a disagreement on a fire pump installation. Flow test shows 42 psi static, 10 psi residual at 475 gpm from an 8" municipal main.
The fire sprinkler contractor plotted the water supply curve and says it cannot support the specified 1,000 gpm @ 100 psi pump; they're refusing to certify the fire pump without a suction tank or another resolution. The mechanical engineer argues the 8" main at 42 psi static should theoretically deliver way more than 1,000 gpm and questions whether the flow test results accurately represent what the pump will actually see at its suction connection. The steep pressure drop (42 psi to 10 psi in only 475 gpm) seems abnormal for an 8" main. The area has aging infrastructure and known low-pressure issues. Looking for the community's input on: (1) Is the fire sprinkler contractor correct to base their analysis on residual pressure under flow conditions, or should we be looking at static pressure as the mechanical engineer suggests? (2) What's the correct NFPA 20 methodology for evaluating water supply adequacy for a fire pump? (3) When you see such a steep pressure drop in a flow test, what are the typical causes and how would you approach resolving this? What solutions have worked for others dealing with marginal municipal water supplies? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 20 (2019) Figure A.4.22.1.3(b) provides a typical diagram indicating pipe for fire pump test connections. In this detail the flow meter loop is shown to return to the suction side of the pump and connect between the fire pump and the suction side OS&Y control valve.
I have seen installations over the years where this connection is placed on the inlet or city side of the OS&Y. This seems to simplify the loop arrangement. Functionally, it would seem to be similar as you would need the OS&Y open to allow some cooling water to reach the circulation relief valve. Is there anything in NFPA 20 that would prohibit this arrangement? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe In order to use pipe and fittings, they need to be "listed for fire protection service."
Do fire pump sensing lines need to meet this listing? What about compressed air lines coming from the air compressor to the air maintenance device, do they need to meet this listing? What about air on the downstream side of the maintenance device? We're curious on different methods to install these components where some fittings & pipe combinations are listed and some aren't (such as copper pro-press for sensing lines). Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We find that the pressure and flow vary between the nameplate and the shop test curve of the UL-listed fire pump.
What is the allowable tolerance for the difference? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe According to NFPA 20, for any pump installation, the NPSH supplied must be at least equal to the NPSH required for the operating conditions specified.
So does the NPSHₐ need to be continuously maintained at or above the NPSHᵣ during pump operation? During the operation of the fire pump, the liquid level of the fire water tank will keep dropping, which may lead to a situation where the NPSHₐ is lower than the NPSHᵣ (unless the fire water tank is built at a very high elevation). Is this situation permitted? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe For scissor stairs having 2 separate standpipe risers (one of them is a combined sprinkler and standpipe system) running 12 floors, how do we size the pump flow rate required?
Can we argue that we can use a 500GPM pump since the Risers are in close proximity to each other and are within one stairwell, or should we use a 750GPM pump following the NFPA 14 sizing of 500GPM plus 250 GPM per additional riser? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm working with a not-so-good flow test on a project that will require a pump because of the flow test.
Where this is getting in the muck is the test flow rate being 712 gpm. The hydrant is about 565 feet from the entry and about 4 feet below finished floor elevation. This is a 5-story, light hazard with 2 standpipes, so the standpipe demand is 750 gpm. Flow test had 44 psi static and 34 psi residual with a 0.9 coefficient through the 2.5" outlet. As you know this is a 750 gpm system demand. The person over me is adamant that we not separate the sprinkler and standpipe systems out - sprinklers and then standpipe - by code when it comes to fire pumps. Even though this is a low-rise building and all we are technically concerned with is an automatic sprinkler system, and if the responding FD has an engine/pumper, the manual standpipe is in their realm. The argument is that they don't want a "partially automatic system" on any project; if a fire pump is to be provided for the project, they insist that the standpipe system connected to it must also be automatic. Back to the 750 gpm thing. At 34 psi, we have 712 gpm, obviously. The thing here is putting a 111 psi, 750 gpm pump on. They're concerned with the NPSH of the pump and not the duty point or the 150% rated test goals. (1) When a fire pump is provided to meet the needs of the sprinkler system, are the standpipes required to be automatic? (2) Is there a requirement here for automatic standpipes that I'm missing? The local jurisdiction has no amendments that affect standpipe requirements different than the model IBC. (3) Is an automatic standpipe here even achievable given the limits of the water supply, or are we causing more issues in testing down the road? If it was local, the FMs have already told me that's close enough and we will make up any flow from our trucks. What am I missing here? I understand clearly that at 20 psi the flow is 1,124 gpm. That's not what I'm trying to accomplish. I am attempting to make the combined system fully automatic per policy at 750 gpm and I'm told it's all good to go. Help a man at wit's end out here. TLDR: How would you approach manual vs. automatic standpipes when a fire pump is provided for a 5-story sprinkler system, but a 750 gpm pump could overtax the water supply? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Does NFPA provide guidance on campus-style fire pump design?
Can I provide two water services (one from each building) and serve out to two buildings? NFPA 20 4.9 implies that campus-style designs are acceptable, but I am not seeing any code lines referencing any further requirements for such a design. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When a new fire pump controller is installed or replaced, is an acceptance test required?
I suppose I know the answer, but I am looking for a code basis. Thank you. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Assuming a jurisdiction requires sprinkler pipe to be bonded to the building grounding system, would a sprinkler system fed from a fire pump be considered bonded since it is attached to the pump which is already grounded?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe TL;DR:
How can surge/water hammer forces be managed in very tall high-rise fire protection system using a single high-pressure pump (~365 psi) without exceeding equipment ratings or NFPA limits? Question: Trying to pre-plan in my mind for some upcoming pretty tall highrises where design teams would like to utilize 1 pump in lieu of a high/low multi-pump set up. I'm coming up with a couple of challenges. For the sake of the problem lets assume the static pressure at the fire pump discharge flange is 365 psi. I'm concerned that fire pump starting methods might create shockwaves/water hammer in high-pressure standpipes whether it be at the start of the pump like across-the-line or end of the curve spike like a wye-delta closed might see. How concerning is creating surge forces that exceed coupling/PRV valve/Pressure Relief Valve listed ratings? First reaction for many like me has always been to utilize soft-start but electrically with generators soft-start has a much higher load that has to be accounted for in the generator sizing because of the electrical engineers have to size them as across-the-line because of the bypass & 600% FLA. Maybe they just have to suffer on their design for FPs to be what it needs to be, but am trying to be accommodating where it makes sense. Is the general method to rely on a main relief valve in these high-pressure systems? NFPA 14 limits us to 400 psi but I'm not finding pressure relief valves that are listed high enough for the static pressure of the system i.e. cal-val at 300 psi, Victaulic at 350 psi. Is anyone utilizing anything like an Amtrol Surge-Trol Tank type products? Maybe VFD controllers to flatten/lower the static pressure? Some additional concerns in my mind are PRV hose valves have a 400 psi rated value and some couplings for example Victaulic might be rated at 365 psi. I know there are higher rated couplings on the market, like 500 psi, but if my static pressure on the system is 365 psi, I could see a surge force exceeding the rated values (zero math to support that claim). I'm struggling to quantify the possible surge force values in the design phase and how to handle that. Reading SFPE Handbook of Fire Protection Engineering 5th edition Water Hammer section pg 1407, it's focused mostly on the closing of valves, and still wrapping my head around if those equations can be applicable/same for pump starting forces. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a facility with an NFPA 13 Extra Hazard 1 sprinkler system.
The client's proposed location of the water storage tank is approximately 33-ft (10m) higher than the level of the protected building and around 100-ft (30m) away. The client's proposed pump house is closer to the building, separate from the tank. My question is - is there a maximum length for the suction feed from the tank to the pumphouse under NFPA rules (13, 20, 22)? I would rather locate the pump house next to the tank and run the delivery main to the building. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When did NFPA 20 start requiring exterior access to Fire Pumps?
I have an older fire pump, sprinklers had to be tested at 50 years, and when this thing was installed, they had no exit door in the pump room. Current NFPA 20 in our jurisdiction (2016) calls for an exterior access door or access from an enclosed stairway or different exterior exit. The AHJ is aware of that. (Sections 4.13.2.1.1) Because it's an older system, I'm trying to see if the exterior exit requirement still applies to the system at the time of original approval. The oldest NFPA 20 I can get for free on NFPA Link is 1996. I cannot find this requirement or the "equipment access" section in this code beyond some parts about when a fire pump is installed wholly outside the building. Anyone with more experience than me know when this started? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a project with a very large Water Storage Tank that requires a 20" suction line from the tank to the suction manifold side of (3) pumps.
Per NFPA 20, at the connection point from the water storage tank to the supply line to the fire pumps as required by NFPA 20 (2019 ed.) 4.16.6.5, where the pump and its suction supply are on separate foundations with rigid interconnecting pipe, the pipe shall be provided with strain relief in Figure A.6.3.1(a). We can find no manufacturer that has a 20" UL/FM strain relief connection. We do, although, have a supplier that makes a 20" Flexible Double Expansion Joint, but not UL/FM Listed. Does anyone know of any other options, or can we just use this flexible expansion joint and get a waiver from the Fire Marshal and EOR? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is it permitted to install fire pump cables, from the controller panel to the motor, through a cable tray using armored cables, at a height of about 4 inches (10 cm) above the finished floor level?
Are there any code or standard requirements that affect this? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is there a velocity limitation or velocity direction provided for the design of private fire service mains?
Is it possible (or acceptable) to have an underground main smaller than the size of the discharge pipe required by NFPA 20? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe What is considered "too loose" for a diesel fire pump exhaust? I'm referring to the vertical section just above the flex of the engine. NFPA just says that you have to secure and shall refer to the manufacturer's instructions, so in this case, it's a Clarke. Thanks in advance. Video is below. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe In California (and other states), are diesel fire pumps subject to emissions requirements, or are they exempt?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe On a fire pump system that has a large PRV on it, should there be a test of just the fire pump, as in the fire pump annual test, and also separately a test with the pump through the PRV?
This would ensure that the reduced-pressure standpipe/ sprinklers work ( system acceptance ). Are these required to be separate tests, or can they be combined? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is it mandatory to install a strainer at the suction pipe of a fire pump?
Or are there specific criteria in NFPA for horizontal centrifugal pumps to determine under what circumstances a strainer may not be required at the suction pipe? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Diesel fuel tank - how low should I allow the diesel fuel level to drop before I fill the tank with diesel fuel for a fire pump?
Should I add diesel fuel when the fuel gauge drops to 3/4 full, 2/3 full, or 1/2 full? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm designing a 13R system. The building currently has a 3/4" domestic water service. The building is in a location that would make installing a new (larger) service a logistical nightmare.
Is it allowed to connect the 3/4" existing supply to a water storage tank (sized per system/domestic demand) in the basement, then build a residential riser from that? If this is allowed, do I only take my calculations back to the storage tank? Do you foresee other problems with this? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Pipe Stands and Bracing I have a 12" fire pump that feeds the "U Turn" in the attached picture. Insurance company is adamant more bracing is needed. My question is what size pipe stands are required for 12", and do I need more lateral bracing for the surge if the fire pump runs? All I can find in NFPA 13 only addresses up to 10". Any thoughts or ideas on codes I may be missing would be appreciated. Thank you! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Does anybody have experience with locating diesel fire pump fuel tanks in exterior locations where the local ambient temperature can drop to below freezing point?
We have an unavoidable situation where we have to locate the fuel tank outside the pump room and we're hoping not to have to build a heated enclosure. NFPA 20 seems to require a heated enclosure, but FM not so much. I am aware that condensation and fuel deterioration are issues to be dealt with, but I was thinking maybe good quality thermal lag of the tank and feed/return fuel piping may be sufficient with just a roof structure above the fuel tank. What are your thoughts on this? any thanks in advance for your thoughts and advice Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
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