Fire pump calculation formulas

Maximum hazard sq. Each pump can discharge lpm bar pressure Hence no. Of 30 kW electric driven motor. Result : M3 Water Tank Capacity only for fire Fire tank to maintain an individual dedicated fire tank.

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Henry Suarez. Arup Debnath. Banang Mulia Permana. Anonymous BJ9omO. Kumararaja Konikki.Make FireRescue1 your homepage. There are two ways to calculate friction loss: the theoretical method or the fireground method — here's the fireground method. There are plenty of things that the pump operator must get done in the early stages of a fire, and none are more important than this.

To determine this, the pump operator must first know the total gallons per minute flow, that is, the desired result on the working end of the hose.

The type of nozzle being used — smooth-bore, automatic nozzle or adjustable gallonage — will determine the gpm. Once the pump operator knows what the desired gpm is, then they must know what size hoses are being used, the lengths of the hoses and any appliances that are part of the hose layout, such as a gated wye. Armed with that information, the pump operator can then calculate the friction loss, the remaining ingredient for getting the right mixture to their firefighting colleagues.

Friction is the force resisting the relative motion of solid surfaces, fluid layers and material elements sliding against each other. Friction loss is the pressure loss due to the friction. In its fire service application, the friction is water sliding against the interior surfaces of the pump, any connected appliances — gated wyes, manifolds or a water thief — standpipes and fire hose.

In reality, understanding friction loss and its place in properly supplying hose lines and fire streams is not that daunting of a task. The basic challenge for the pump operator is to develop the proper pump discharge pressure necessary to overcome the friction loss in a fireground set up to ensure that the firefighter on the nozzle will have the appropriate amount of water to suppress the fire.

There are two ways to calculate friction loss: the theoretical method or the fireground method. Theoretical calculations are generally best used for pre-fire planning, developing specifications for pumping apparatus and calculating problems ahead of time, such as creating pump charts.

Theoretical calculations are typically not an efficient means of calculating friction loss on fire scenes. Many times, instructors teaching pump operations bring out the theoretical method, along with its equations, at the beginning of the training process.

I was very fortunate at the beginning of my firefighting career to join a department where that was not the case. My pump operator instructors focused early on developing my skills in using such tools as the hand method for calculating friction loss.

They also emphasized memorizing the friction loss for the pre-connected hand lines and typical hose layouts that I would encounter as a pump operator. This is an extremely valuable tool for both learning and teaching what the friction loss is for various sizes of hose and various gpm flows. Below is one example of a hand method for calculating friction loss in various sizes of hose. For a 3-inch supply line flowing gpm, the friction loss per foot section would be 9 psi: 3 squared equals 9 psi.

Memorizing this much simpler than it sounds. All you must remember is the friction loss for each, 14, 24, 35 and 62, respectively. Those are the amounts of friction loss per feet of hose based on the gallonages above. Change the flow setting on the nozzle to gpm on the same foot line and the friction loss is 35, if you increase the hose length to feet, the friction loss becomes 62 psi. To figure the required discharge pressure, add up all friction loss — in the hose and any appliances — plus the required nozzle pressure.

Thus, for that apartment complex layout I mentioned earlier, the calculation would look like this:. Do your homework about the different hose loads, appliances and nozzles used in your department and what each contributes to friction loss, that is, what are the friction loss points. A best practice employed by many skilled pump operators is creating a cheat sheet containing what those friction loss points look like. Source: University of Alaska, Fairbanks.

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Pump Power Calculation Formula | Specific speed of a centrifugal pump

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fire pump calculation formulas

Alvin Smith. Mohamed Azhar Mohamed Ismail. Jason Mullins. Kei Chan. Ali Aimran. Elaya Raja.If you are utilizing the city water supply as the primary source for the pump, you need to make sure that an accurate city water test is used. Some good rules to follow are: Make sure the water test is less than a year old. Make sure the water test is performed as close to the tap point as possible.

Make sure the test is taken during the time of highest water use for the area. In a cold climate, testing during the summer may be a better choice, since residents are watering their lawns and commercial properties are using more water for cooling. Additionally, in highly residential areas, peak morning use typically occurs early in the day, between and 9 a.

Basi Calculation for Pump & Tank Selection

Another consideration regarding the water test is this: Did the city flow enough water to meet percent of the fire pump design point? This will ensure that the municipal supply will provide enough volume to meet the system demand. If not, request a new test using more hydrants or plot a water supply curve see Figure 1.

If you are using a private water supply, lake, or ground-level storage tank, you must remember that you are not permitted to use a suction lift with a fire pump.

fire pump calculation formulas

Thus, if the water supply is located below the suction inlet to the fire pump, you may have to utilize a vertical turbine fire pump in lieu of the other types of pumps available.

The last job parameter you need in order to size the fire pump is the required flow for the systems the pump will be serving sprinklers, standpipes, or other. For standpipe systems, this flow is related to the type and size of the structure the pump is protecting. In any case, the demand of the system will dictate the pressure and flow required. Calculating standpipe system pressure Two types of structure calculations for pressure are available. One is for high-rise structures buildings greater than 75 feet in height, measured from the lowest level of fire department vehicle access to the floor of the highest occupiable story and one is for non-high-rise structures.

This is a factor because any high rise requires a pressure of pounds per square inch psi at the top of the structure while flowing the rated gallons per minute gpm of the fire pump.

This discussion concentrates on high rises because the pressure calculations for most non-high-rise buildings are determined through the use of software specifically designed for fire sprinkler hydraulic calculations. These programs are used by sprinkler contractors to keep their pipes as small as possible, which controls the cost of the job.

When calculating the water pressure for a high rise, it is a good idea to use a calculation sheet such as the one shown in Figure 2.

Hand Method for Calculating Friction Loss for Firefighters

If you use a calculation sheet, a few variables need to be filled in:. Pressure drop in the backflow prevention device and water meter Friction loss in the most remote standpipe when flowing gpm Elevation change For the example in Figure 2, the parameters are: Building height: feet City water pressure: 45 psi static; 35 psi residual Required flow rate: 1, gpm Assume that the pump is 1, gpm for this example.

As you can see, the calculated required pump psi is psi. A similar calculation can be used for a non-high rise, by changing the psi to the end head pressure 15 50 psi, depending on the head. However, the friction loss and pipe sizing become an issue when doing this calculation, which is why most contractors and sprinkler designers use software.

A note about pressure One thing that some engineers forget is that the pump will discharge at a much higher pressure at churn no flow than at the design point. This is almost never the case, but different pumps and speeds affect the churn pressure, so you should always look at a curve to determine the shutoff pressure. The reason for reviewing this is typically to understand what the maximum pressure no-flow churn will be in the system to determine whether high-pressure fittings are needed.

Calculating pump gpm To calculate pump gpm, two sizing methods are available, the standpipe method and the sprinkler area calculation.We use cookies to provide you with a better experience.

By continuing to browse the site you are agreeing to our use of cookies in accordance with our Cookie Policy. When starting a fire pump design, the most important item to consider is the water supply. If you are utilizing the city water supply as the primary source for the pump, you need to make sure that an accurate city water test is used.

Some good rules to follow are:. In a cold climate, testing during the summer may be a better choice, since residents are watering their lawns and commercial properties are using more water for cooling. Additionally, in highly residential areas, peak morning use typically occurs early in the day, between and 9 a. Another consideration regarding the water test is this: Did the city flow enough water to meet percent of the fire pump design point?

This will ensure that the municipal supply will provide enough volume to meet the system demand. If not, request a new test using more hydrants or plot a water supply curve see Figure 1. If you are using a private water supply, lake, or ground-level storage tank, you must remember that you are not permitted to use a suction lift with a fire pump.

Thus, if the water supply is located below the suction inlet to the fire pump, you may have to utilize a vertical turbine fire pump in lieu of the other types of pumps available. The last job parameter you need in order to size the fire pump is the required flow for the systems the pump will be serving sprinklers, standpipes, or other. For standpipe systems, this flow is related to the type and size of the structure the pump is protecting.

In any case, the demand of the system will dictate the pressure and flow required. Two types of structure calculations for pressure are available. One is for high-rise structures buildings greater than 75 feet in height, measured from the lowest level of fire department vehicle access to the floor of the highest occupiable story and one is for non-high-rise structures.

This is a factor because any high rise requires a pressure of pounds per square inch psi at the top of the structure while flowing the rated gallons per minute gpm of the fire pump. This discussion concentrates on high rises because the pressure calculations for most non-high-rise buildings are determined through the use of software specifically designed for fire sprinkler hydraulic calculations. These programs are used by sprinkler contractors to keep their pipes as small as possible, which controls the cost of the job.A properly sized fire pump is critical to ensuring your fire sprinkler system will work appropriately and keep your building protected.

fire pump calculation formulas

Depending on the size and layout of your building, your fire pump needs to maintain a specific amount of pressure, measured in gallons per minute GPM. The standpipe method is an easy method of calculation that can be used by smaller buildings. Under the standpipe method, calculations are based on the number of standpipes your fire sprinkler system relies on.

According the protocol, the first standpipe in your building is required to maintain a pressure rating of gpm. Any additional standpipes must maintain a pressure of gpm, and the whole system must be pressurized to a maximum of gpm. Because gpm is the maximum pressure allowed by the standpipe method, it is ideal for smaller buildings but becomes a problem for larger buildings that require additional standpipes. Sprinkler area calculations are a more complicated way to calculate fire pump size requirements, but they are extremely effective for larger buildings and buildings with a variety of fire hazards.

Before sprinkler area calculations can be made, hazard levels throughout your building must be defined. Sprinkler hazard calculations are defined as follows:. Most large buildings have areas in a variety of different hazard levels. In this case, the highest hazard level in the building will be used to determine the fire pump size requirements.

fire pump calculation formulas

Once the required size for your fire pump has been determined, the next thing to do if figure out which type of fire pump is best suited. The three types of fire pumps include:.

Horizontal split case fire pumps, also called double-suction fire pumps, are the most common types of fire pumps. They typically come rated for gpm.

Interestingly, horizontal split case pumps were the first type of fire pump used in fire protection systems. Inline fire pumps usually take up less room and have lower installation costs than horizontal fire pumps, making them ideal in certain situations. NFPA protocols dictate that positive suction pressure is required for a fire pump to work properly.

In areas where this is not possible, a vertical turbine fire pump may be required. A properly sized fire pump is critical to ensuring your fire sprinkler system keeps safe your building and the people and property within it. Contact Us. Let us know how we can help you and a Guardian representative will contact you within 24 hours. Contact Us Today! Powered by Nearby Now. Our Service Areas. All Rights Reserved.Register now or log in to join your professional community.

There are two main factors in GPM calculations: 1. Area calculation according to hazard type :-The density is multiplied by for light and ordinary and for extra hazard a Light hazard- density 0.

So for the example with a 2 h. Each figure can be calculated using simple math. How the concepts are developed is explained below.

The engine pressure is calculated by plugging numbers into each figure and adding or subtracting them. Products By Bayt. Use Our Mobile App. Get Fresh Updates On your job applications, and stay connected. Download Now. Start networking and exchanging professional insights Register now or log in to join your professional community. Follow How to calculate GPM water flow for a fire pump? What are the procedures?

Fire Pump Sizing and Calculations

Upvote 0 Views Followers 8. Write an Answer Register now or log in to answer. Upvote 5 Downvote 0 Reply 0. Upvote 4 Downvote 0 Reply 1. Upvote 0 Downvote 0 Reply 0. This nozzle gives the stream its shape, reach, and velocity. By definition, a fire stream is a stream of water after it leaves the nozzle until it reaches its final destination, which is usually the seat of the fire.

As the streams are being produced, they are affected by the discharge pressure, nozzle design, and nozzle setting. The officer in charge of a fire needs to determine the amount of water needed to extinguish the fire and choose the appropriate hoseline and nozzle that will deliver the correct GPM. Large fires make for good news coverage, but in reality they happen because the firefighters were unable to place enough water at the seat of the fire to overcome the Btus being produced.

The amount of water discharging from a smooth bore is determined by the nozzle pressure and the inside diameter of the opening.

The formula for determining the GPM flow from a smooth bore nozzle is as follows:. Answer added by hifzoor qureshi 2 years ago. See More Answers.