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To me, it makes more sense to locate a backflow on the suction side of a pump. However, I have recently run across a facility with the backflow downstream of the pump (discharge side).
The main fire pump controller is connected between the the first check valve and the backflow preventer. The jockey pump is connected after the backflow preventer. Here's the problem: when the first check valve fails, the main fire pump continuously starts & stops because the pressure is bleeding off they the relief valve while the jockey pump remains idle. Is this an acceptable scenario? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
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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 I'm reviewing a apartment building that meets the requirements for an NFPA 13R system.
My questions: A pump is going to be required for this project and they are proposing to use a booster pump on the incoming waterline at the property line to reach the required pressure for domestic and fire demands. Is a combined domestic/fire pump like this allowed? It would be a private pump. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I am looking at a project that shows 6-inch underground lead-in to a riser room. The specs however call out the install of a 1,000 gpm pump. NFPA 20 shows that for a 1,000 gpm pump suction sizing should be no less than 8-inch diameter.
Is a 6-inch even allowed for this application? 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 are having problems getting a flowmeter to accurately read the flow rate that matches what we are measuring downstream out through a test header. A reading using calibrated pitot gauges outside at 1,500 gpm, for instance, is showing 1,900 gpm on the flowmeter inside.
Military specifications for the project require that the flowmeter read accurately, and that the system be piped such that flow must go through the flow meter out through the pump test header. The flowmeter manufacturer has recommended using a stream straightener upstream of the flowmeter to better streamline the flow through the meter and get more accurate readings. Does anyone know of a stream straightener that could be used in a fire pump test loop arrangement? I would think it would have to be listed, but that's just a gut feeling. I don't currently know of any listed stream straighteners. We generally need to meet the black and white code and specifications mandates spot-on without any code alternatives, if possible, being that it's a military project. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can I install a concentric reducer in the vertical position and a 90 on the suction side of a vertical inline pump?
The feed is coming from above the pump, and we don't have space for a 90 and an eccentric reducer. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Can a 3-phase, 480 volt electric service inside the fire pump room be reduced down to 208-volt 3-phase with a transformer properly sized for the 6x amps of demand of the the fire pump serving the building?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 20 specifies a minimum size for suction pipe before a fire pump, to reduce the water velocity and avoid cavitation (among other things). NFPA 20 states that this only applies to 10-pipe diameters of length before the fire pump.
We have a very long run from the backflow preventer at the service entry and the fire pump room. Hydraulically, this long run works with a long 4-inch feed, which would then upsize to 6-inch right before the 450 gpm pump for the 10-pipe diameters. My question is, am I allowed to drop the main size between the backflow and the fire pump? Hydraulically I don't see why not, we're not dipping below 20 psi anywhere on the system and we appear to meet code. Intuitively I've never dropped pipe size to pick it back up, but this situation with the pump feels a little different. This is above a multi-family unit, so 6-inch steel is nearly impossible to fit within short open-web joists and would be a major issue for the building owner if we had to drop a soffit. Thanks in advance for your take! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We are designing a warehouse which has a system demand of about 150 psi at 2,000 gpm.
There is an existing facility with a 150 psi @ 1,000 gpm rated pump installed approximately 1/4-mile (350 m) from the warehouse. We are planning to add a new 150 psi pump at 1,000 gpm near the warehouse roughly 65-feet (20 m) from it. Is there any code limitation we might hit to serve one building with two separate pumping stations installed remote from each other? How would you recommend we set the pump operation sequence for the two pump rooms? Each pump room will have an electric, diesel, and jockey pump. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 20 Section 4.15.5.1 (2016 Edition) requires a listed OS&Y gate valve to be installed in the suction pipe, but the annex of NFPA 20 suggests it should be as far as practical from the pump suction.
Would a control valve (OS&Y) on the backflow preventer meet this control valve requirement of Section 4.15.5.1? Assuming a city water supply, the backflow preventer control valve is listed for fire protection, there is still a valve'd bypass connected between the backflow preventer and pump suction, and the backflow is located a minimum of 10-pipe diameters from the suction flange. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a project where the consultant is wanting to use a previously-installed 10-story building tank and fire pump to supply a new 14-story building up to its 6th floor, then add a booster pump to carry water to the upper floors.
Is this even acceptable by code? The new 14-story will be built next to the existing 10-story building. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 20 5.6.2 requires a fully-independent and automatic back up pump for very tall buildings. This project is just under 50 stories with a pump and back up several levels below grade serving the lower zones and another pump and back up several levels above grade serving the remaining zones.
The project’s electrician cannot meet the power requirements for the worst case scenario, which would be all (4) pumps operating at once (if the primaries are running, but not at full capacity). The request is to interlock the primary and back up on the respective level, so only one pump is running on the level at a time (for a max total of two pumps running in the whole building). Would interlocking the pumps on their respective levels still satisfy the requirements of NFPA 20 5.6.2 (copied below)? NFPA 20 5.6.2 Fire Pump Backup. Fire pumps serving zones that are partially or wholly beyond the pumping capability of the fire department apparatus shall be provided with one of the following:
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I always seem to miss listing a pressure gauge on a project. Are any required above what I have in my checklist below?
Sprinkler:
Standpipe
Pumps
Moderator note: thanks in advance for feedback, we're developing a cheatsheet on this topic in the near future Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Do fire pumps typically come balanced from the factory for the desired flow and pressure?
I know they are supposed to, but (just like any other pump) is their balancing done similar to a regular pump to get the desired pressure so that the pump operates at its rated duty point? I am aware that many factors affect final pressure discharges (such as friction loss, etc.). Have you ever seen pump manufacturers calibrate pumps to the desired flow/pressure in the field? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm working on a a high-end hotel which will have a vertical turbine fire pump above a water storage tank.
Can we waive a minimum pump submerge depth by installing an anti-vortex plate between the pump's bell and the strainer? The fire pump is a 1,500 gpm vertical-turbine type, located directly above the water tank. The tank depth is 6'-3" from the overflow bottom down to the tank floor. The water tank area is 2,408 sqft. The selected pump recommends 51.63-inches as a minimum submerge depth. This is in addition to a 12-inch clearance between the bottom of the strainer and the tank floor. The water level to be maintained inside the tank then must be 63.63-inches (95,511 gallons). The remaining active volume in the tank after extracting the required volume will be 112,582 - 95,511 = 17,071 gallons. This is not enough to run the pump set for the required time under NFPA 13 2019 (Table 19.3.2.1 and 19.3.3.1.2). Can adding an anti-vortex plate between the pump's bell and the strainer waive this minimum submerge depth? If not, what might be a recommended solution for this? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Hi, all! I came across this forum by accident at the perfect time. I am having a dilemma with the building department.
I am conducting an annual flow test on a 500 gpm (at 100 psi) fire pump from the test header off the pump discharge with the valve closed as to not disturb the system. I achieved 100% and 150% with no issues and the curve was almost identical to the pump's design curve. The Department of Buildings is rejecting the test because the test was conducted from the discharge manifold. I was trying to avoid flowing from the roof because it's a very high end building and did not want to risk anything. Now, this system has been recently installed and the jockey pump panel is reading 100 psi on the system. When I tested my pump, it pushed out 168 psi on discharge and 48 psi on suction for a net of 120 psi (the pump is rated at 124 PSI for churn). I can conduct the test from the roof with no issue as long as the building feels comfortable with their storm drain's ability to handle the flow, but I am worried about over-pressurizing the system. Am I permitted by code to test off the header and not from the roof? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe If a fire sprinkler systems is designed for "life safety" purposes, should not a primary and standby fire pump be provided? Why are standby pumps not required to improve reliability for these systems?
Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe We have a building with a double check backflow assembly on the suction side of a fire pump. Normally there is a minimum of 10 pipe diameters of vertical plane pipe just before the suction flange.
Is the double check backflow allowed within that distance? Are there requirements for the backflow to have flanges vs. grooved connections? A colleague said the control valve should be OS&Y rather than butterfly on the suction side only. Why would this be the case? I would assume the OS&Y would reduce turbulence better than a butterfly, but wouldn't the checks also cause turbulence? Thanks in advance. Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe A couple of questions about an electric vertical inline fire pump:
(1) Is it necessary to build a rated room around a fire pump that is located in a boiler room that is already 2-hour rated construction? (2) Is it required to have a concrete base poured below a vertical fire pump if we can bolt the pipe flange stand to a concrete floor? Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe Some fire pump assemblies have closed-test loops. When we circulate water through this closed test loop, why does the suction pressure not increase?
I'd be interested in understanding the physics of the situation a little better here. 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 Do you know of any specific guidelines for space around a fire pump skid to leave in a fire pump room?
I have always worked off the notion of "enough clearance to get around and work on a pump" but that is very subjective. So, I have a self-imposed 3-foot clearance around the edges of a skid. Is there anything more specific in generally adopted codes or standards? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe When/why would an eccentric reducer ever be installed on a fire pump's suction side with the flat side on bottom?
Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe I have a project where the fire pump room is located on a third floor level.
Are there any specific requirements regarding the location of a fire pump? Is this location acceptable? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe |
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