How to calculate GPM (water flow) for a fire pump? What are the procedures?

There are two main factors in GPM calculations: 1. Area calculation according to hazard type :-The density is multiplied by 1500 for light and ordinary and 2500 for extra hazard a) Light hazard- density 0.1 plus hose stream 100 GPM Example: area 15000 square feet 1500 X 0.1 = 150+ 100 hose = 250 GPM pump b) Ordinary hazard- density 0.15 plus hose stream 250 GPM Example : area 24000 square feet Calculation 1500 x .15 = 225 + 250 = 475 GPM c) Extra hazard density 0.3 plus hose stream 500 GPM Multiplier area for extra hazard is 800 square feet Example : area 22000 extra hazard 800 X 0.3 = 240 + 500(hose) = 740 GPM 2. Stand pipe calculation According to NFPA -14 states that the GPM required for the first stand pipe is 500 GPM, and each additional stand pipe requires 250 GPM with maximum allowed 1000 GPM for any more stand pipes. For example if we have 2 stand pipes then 500 GPM for first one plus 250 GPM for the second one equal 750 GPM total required pump GPM.

Measure the head(Delivery-Suction),

Calculate power(Can get it from the motor),

Calculate Friction losses,

Then Power=QXHXDensityxg,

Q=Water flow

How to find density in lpm/m^2 If presure=0.5bar Min pump cap=350gpm Covering area=12m^2

which is pumped to the pipes. Then by the following formula the velocity can be calculated: Mass flow = Density * Velocity * Pipe Area

(G) Calculate your “Total Pressure Head” and enter it on your Design Data Form. Now for the flow formula: Multiply the pump Horsepower times 2178 (a constant value)  and then divide by the Total Pressure Head in feet. So for the example with a 2 h.p.

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.

• EP = Engine Pressure

• NP = Nozzle Pressure

• FL = Friction Loss

• Elev = Elevation Loss or Gain

• App = Appliance Friction Loss

The equation EP = NP + FL + APP + ELEV is the basic equation every pump operator needs to calculate when operating the fire pump 

A hoseline needs to have a nozzle attached to its end. 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.it is not the pressure of a stream that extinguishes a fire but the amount of water in GPM  that cools a fire. 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 officer as well as the pump operator need to know the GPM flow from different nozzle tips to know how much fire each can extinguish. As a general rule, the maximum nozzle diameter should not exceed one-half of the size of the hose to which it is attached--for example, a2½-inch handline should not have a smooth bore nozzle any larger than1¼ inches. A1¾-inch handline should have a nozzle tip no larger than7⁄8 inch.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:

.D2√P (D = nozzle diameter; √P = square root of pressure)

For example, a one-inch smooth bore tip will have a discharge of gpm:. × ×7. = gpm.

how to calculate the gpm in fire fighting

 

Power=QXHXDensityxg,

Q=Water flow

H= Head

g= Gravity 

i couldnt find the anser, but i want a detailed answer if anyone is willing to chat online and discuss.