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How do you determine the effective capacity of a water storage tank for fire protection purposes?
Where are the unusable limits set for the bottom of the tank suction and the top air gap? Is there a mandate for either of these in code or standards? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
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Existing remote church with water provided by a storage tank. The church plans on building a separate meeting hall that does not connect to the church. These buildings will be approximately 200 feet apart. This new building will require sprinkler protection.
Is it possible to use the existing storage tank to serve both buildings? The current tank is sized just for one fire area, so it is not for two simultaneous fires. Normally, two separate buildings have two services, but I wonder if there is an exception for storage tanks in remote areas. 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 Has anyone ever used a slosh damper water tank on a roof as part of the fire reserve for the building?
The project is located in NYC. If so, are there any special requirements that need to be adhered to? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I work for a local fire department that does plan reviews for fire protection systems. We are reviewing a project that requires 40,000 gallons of stored water. They are proposing using multiple fire water tanks and eight 5,000-gallon tanks.
While NFPA does not restrict the use of multiple tanks, I would like to see fewer tanks than eight. I am more inclined to allow two separate tanks at the most. However, I wanted to see what others thought and if there was a standard understanding or practice to number or size of tanks to the total needed water demand. Thanks for any help. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When sizing an elevated fire water storage tank for the minimum supply duration of a sprinkler system, should non-remote areas (areas closer to the tank) of the system be considered as well?
Since sprinklers closer to the tank would be under higher pressure, they would discharge more water than those in the remote area. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe When doing Calculations for a building that has a fire pump that is fed by an above-ground water tank, what do I use for available supply?
The fire Pump is 75 psi at 1,500 gpm. City water refills the water tank. City water is 104 psi static, 81 residual at 1,453 gpm flow. Do I factor in the tank by figuring the pressure created by elevation, or do I bypass the tank and use the city pressure in combination with the fire pump? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am working on a fire pump station project.
As the water tank ( 2 x 50,000 gal) is dedicated to the fire pumps only, a possible stagnation is expected, and hence, a recirculation pump for the tanks will be the best solution. I saw in many forums or searches that an 8-hour refill needs to be incorporated for the pump sizing, however, I couldn't find anything solid on NFPA 22 documents regarding recirculation. Can someone direct me to the NFPA reference for the recirculation requirements? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Our high-rise facility consists of apartments, condominiums, retail on the bottom floor, restaurant tenants on the top floor, and (3) levels of underground parking. We are 9 stories tall out of the ground.
They have great water pressure at the site with 140 static and 118 residual, flowing about 1,900 GPM, but with our floor-to-floor distances, I cannot get 100 PSI at the top of my standpipes. The building footprint is spread out, so I will need (8) standpipes to cover the hose lay inside the building (fully sprinklered). I'm assuming one 1,000 gpm pump will cover all the standpipe demand. To complicate matters, this is in a seismic area D classification, and with it being a high rise, I am required to have a secondary on-site water supply. The intent was to install an underground tank to supply the fire pump or pumps, if necessary. My thought was to supply water directly from the city main to the tank, and if there is ever a break in the city supply line, the pump would be served from water in the tank, which would have enough capacity to serve the facility for 30 minutes. Is 30 minutes the duration I need? What do you think about how I plan to serve the building? Would that meet the requirement for a secondary water supply? Do I consider the standpipe demand when sizing the underground tank, or just the most demanding area of my sprinklers? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe If the system demand is 321.5 gpm for an Ordinary Hazard Group 2 system, do you add the 250 gpm hose allowance before or after calculating the 90-minute supply?
For example, 321.5 gpm + 250 gpm = 571.5 gpm x 90 minutes = 51,435 gallons, or, 321.5 gpm x 90 min + 250 gal = 29,185 gallons. Looking for input to order a water storage tank and the owner is disputing the water storage tank size. We told them we would need a 52,000 gallon tank. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Suppose on-site water storage for firefighting is required, and an existing tank is on-site sized for the existing building.
Can I add a second tank on site (not connected to the first tank) and just size it for the additional water required for the second building? Ex. A larger building requires a 10,000-gallon tank, while a smaller building requires a 5,000-gallon tank. Can I just install one new 5,000-gallon tank (10,000-5,000 = 5,000 gallons)? Or would the tanks need to be connected so there is no shortage of water? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe How do you size a water storage tank for fire flow when the city supply is significant, but not sufficient for Fire Flow?
For instance, if I have 1,500 gpm available from the city at 20 psi, but I need 2,000 gpm for Fire Flow, is the water storage tank sized for 500gpm for the required duration? Or do I need to size the tank for the entire 2,000 gpm minus reliable refill? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe A building 2,880 sqft, 20-ft in height, Type IIB with classification of 4 for occupancy hazard.
When I calculate the gallons needed for a water storage tank, is this based off a 2-hour fire flow per NFPA 1142? If so, where can I find that requirement? 2,880 sqft x 20-ft height = 57,600 cubic feet / 4 occupancy hazard x .75 = 10,800 gallons. Is this 750 GPM x 120 minutes for a total of 90,000 gallons? Huge difference between the two. Thanks. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a floating dock standpipe with hose valves in the ocean be ran with PVC pipe?
NFPA 307 doesn’t go into detail about materials used but reverts back to NFPA 20, 22 and 24. This is in Florida. The AHJ wants it full of water so I have to issues, it’s too heavy to mount on the side of the dock, it’s not very big and it will be in the water or very close with high tide, so corrosion is inevitable. Is there anything stating Schedule 40 or 80 PVC is listed or acceptable for such use? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a project with Miscellaneous Storage of Class I commodities up to 12'-0" and Group A plastics up to 5'-0".
The water supply is a tank fed from a well. Based on NFPA 13-2016 Table 13.2.1, I designed to Ordinary Hazard Group 2 with a 90 minute duration of available water. My original demand was 57 psi at 385 gpm. Our pump supplier provided a vertical in-line pump rated to 80 psi 400 gpm. The client is now unhappy about the volume of water being required so they are removing the Group A plastics from their building so we can calculate to OH I with the new demand being 41.5 psi at 304 gpm. We have already installed most of the system and the pump is ready to be delivered soon. Is it okay to have an oversized pump? Can it be limited to a smaller flow to accommodate the new demand? My worry is that it will flow at the rated capacity and if we are sizing our tanks 10,000 gallons less than originally planned we would run out of water. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe 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 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 |
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