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I have a project that I am looking at that right now and it is supplied by a private 75,000 gallon water tower for their current systems and domestic water supply. There's no city tie-in, just fed from their private well.
They are upgrading and adding sprinklers in other areas and will need a fire pump. The hazard classification will require 120 minutes of a water supply. That 120 minute supply is roughly just under 250,000 gallons. Can I somehow tie into the water tower underground that comes into the building and connect a new tank that will supply the new fire pump to meet these requirements? That supplies me with 75,000 gallons, so presumably I would only need another 175,000 gallon tank. Or do I need a separate tank for the 250,000 gallons? I am not sure if the well pump into the tower matters or if that can be figured into the gallons needed as well. Looking for advice on how to approach this situation. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
4 Comments
We're designing an ESFR system for a warehouse where the city water can supply enough to meet our 2,000 gpm demand, but the local ordinances prevent a fire pump from being supplied directly by city water lines.
We are planning to install a 13,000 gallon bolted water tank for this reason. NFPA 22 (2013 Edition) Section 4.1.4 allows tanks to be sized so that the store supply plus automatic fill can support demand over the required duration. However, Section 4.1.5 requires break tanks to be sized for a 15-minute duration of 150% of the fire pumps rated capacity. 13,000 gallons is enough to supply our demand with the added city refill rate, but is not enough on its own for a 15-minute pump supply duration. Does Section 4.1.5 apply to my situation? I'm not using an actual break tank, but the bolted tank is being used in a break tank-like fashion. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Last week someone asked a great question about the limits of where NFPA 20 starts and stops.
In a similar vein, what are the limits of where NFPA 22 and NFPA 24 start and stop for a typical system with a water storage tank, fire pump and private mains? We had a question at work yesterday as to whether NFPA 24 or NFPA 22 applies to pipe before a water storage tank. It'd be helpful for us to understand these limitations in addition to the conversation last week. Thanks in advance! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I recently heard of an incident where the fire water return from a flow meter on a fire pump was connected low from a tank and it did not work appropriately. So as a solution they decided to connect it high on the storage tank a and somehow this configuration fixed the issue.
Both connections would have the same head due to elevation so it does not make sense to me why one would work but not the other. Why does it matter if you connect a return loop to a fire water storage tank near the top of the tank rather than near the bottom? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a project where window sprinklers are being used as part of a 2-hour Fire Barrier.
The engineer wants the second water source to be enough to run for two hours (that would mean we'd need about 40,000 gallon tanks) in an already-designed building. Others are arguing that the primary water source needs to meet the listing but the secondary water source can be 30-minutes as that's when the fire department would hook up and operate. What is the required duration for the secondary water supply? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have an underground water storage tank (concrete) with two compartments; Tank 1 and Tank 2. Our fire pumps are vertical turbine type: 1 duty and 1 back-up. Both suctions of each fire pump are located only at Tank 1.
Is this code compliant? Or shall we relocate the suction of the back-up fire pump into the Tank 2? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a Fire Marshal that is asking us to "show how the fill line can refill the [water supply] tank in a maximum of 8-hours, per NFPA 22 Section 14.4.2".
The tank we're proposing will be supplied by an existing well, but we do not have information on well capacity. What parameters should we be looking for on well capacity? Do we have to test for both flow and time? Is the computation on refill as simple as the flow rate (gpm) x time (8-hours) to get the contribution from the well? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe This may sound like a strange question, but here it goes.
Is there a way to downsize a fire water storage tank based on the refill rate supplied by the city? I know that in Houston there was a company that supplied calculations showing that the refill rate could supply the tank at a refill rate based on the flow test. Could anyone substantiate this principle? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe What is the required duration for a Secondary Water Supply within Seismic Zone?
IBC Section 403.3.3: "The secondary water supply shall have a duration of not less than 30 minutes as determined by the occupancy hazard classification in accordance with NFPA 13." Does this mean minimum 30 minutes, with the gpm/demand determined by NFPA 13? Or the minimum duration is also determined by NFPA 13, such that the secondary water supply could require an even longer duration, like 60 minutes? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm looking at a few projects that have fire pumps and above-ground cylindrical storage tanks for fire protection.
Some projects I have seen have recirculation after the fire pump discharge underground and back into the storage tank. Frustrated I can't find much on this in NFPA 22 or elsewhere. Is this part of a means for freeze-protection, or to keep the water from getting stagnant, or for pump testing (in which case I guess it would have to branch off from the flow meter)? Or is it likely engineer preference? Is it a military requirement? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is there any NFPA provision for forbidding a fire pump to start in the event a water storage tank has a water level that is too low?
I'm wondering what might happen if the water storage gets down to ~25% of the design level, or lower, and the potential need to shutdown the pump before it runs dry. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We are bidding a job that may possibly need a 1,250 gpm rated fire pump due to not enough flow from the city. Our test was 43 psi static, 35 psi residual at 872 gpm. We will need to include a ground suction tank.
How do I correctly include or simulate a ground suction tank in my hydraulic calculations? We use the Sigma Hydraulic Calculation program. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We're looking at a fire protection system, Ordinary Hazard Group 2, that requires primary fire protection water from a storage tank.
We are looking at three options, (1) above ground insulated with a heater, (2) underground concrete and (3) underground fiberglass. I am curious what the community here sees around the industry as being the most common choice here? The job site already has substantial excavation going on and the job is located in the north east so freezing is a concern. There will be no private hydrant so we don't see the need to carry hose allowance in our tanks sizing. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a commercial pool be used as the required secondary water supply to a high-rise sprinkler system?
The 2019 IBC/CBC Section 403.3.3 requires an automatic secondary water supply in certain seismic design categories. This is typically met by installing a dedicated tank that meets the minimum demand for 30 minutes. I have a developer asking if they can run a feed line to their 100k +/- gallon commercial pool so it can serve this purpose. Outside of the engineering challenges and value engineering their team must address, I'm wondering if this arrangement is even allowed. I cannot find anything in IBC/CBC, NFPA 24, NFPA 13, etc. that wouldn't allow this. Any help is appreciated. Section 903.3.5.2 (IBC 2012)/Section 403.3.3 (IBC 2015) requires and automatic secondary water supply. I am an FPE and I work in a jurisdiction (Hawaii) that has never required this secondary water supply due to local code amendments to IBC. Recent code revisions now require this secondary supply, and I now have my first project subject to this requirement. I'm planning to meet this requirement as as follows;
Am I on the right track here? Is this primary/secondary supply arrangement viable? Does anyone foresee any code or other issues that may be a problem with this arrangement? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a water storage tank that is leaking but cannot find the leak.
They have scoped the pipes, used dye to try to track with no luck. Does anyone know if ground penetrating radar or some other thing that we can try to locate this leak? Any help is appreciated! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We design fire protection systems for large industrial plants with a large area network running in the kilometers.
In such case there could be chances of surge due do sudden closure of a deluge valve, check valve, or fire pump. We do not have time/expertise to carry on surge analysis on software. I have heard about using tanks for surge. How would we go about sizing an anti-surge tank? Is there any basic guidelines based on fire water flow rate/pump discharge pressure to get first cut sizing of a surge protection tank? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a water storage tank and a diesel fire pump on our project.
Is there any requirement for the pressure relief valve discharge pipe, when connected to a supply tank, to be extended below the lowest possible water level? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a fire sprinkler system with a 550 gpm total sprinkler demand (including hose allowances). The supply duration is 60 minutes. There is no city water supply and we are only utilizing a storage tank.
Is the tank required to have a minimum capacity of 33,000 gallons? Or, could we rely on fire department response, potentially reduce the tank size, and have a manual fire department connection for tank refill? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a project with a limited water supply that makes it impossible to automatically replace the required fire water in 8-hours.
Could a larger (1.5 x the required fire flow) water storage tank be an option? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Our fire water demand capacity is 60,000 gallons, but our current water tank storage capacity is 30,000 gallons. We don't have any space near our current fire water storage tank.
Is it possible to make another (second) tank with a capacity of 30,000 gallons and connect it to the old tank through pipe? Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe I am currently working on an existing high rise building that requires a fully automatic sprinkler system to be added and the AHJ is requiring a water tank to be added on the property to serve as a secondary supply.
There is no room for a secondary supply. Can a pool be used to substitute a water storage tank that will supply the building through fire pumps? What codes could back up this option? Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe How can we prevent the formation of algae or microorganisms in water storage tanks for fire protection due to the water being stagnant?
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I'm putting together design-build requirements for a new single-story construction building. The flow test pressure is borderline in my opinion so I'll be calling for a fire pump.
When is a water storage tank required with a pump? I don't think the system needs one, but I just want to be sure. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe Is it permissible to consider the refill supply for a water storage tank when sizing the tank?
The supply would come in above 20 psi. Thanks in advance. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe |
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