Pump head = net head + water head loss Net head refers to the height difference between the suction point of the pump and the high control point, such as pumping water from a clear water pool to a high water tank. The net head refers to the height difference between the suction port of the clean water pool and the high water tank.
The most commonly used calculation formula for pump head is H=(p2-p1)/ρg+(c2-c1)/2g+z2-z1.
Among them, H——Head, m; p1, p2——The pressure of the liquid at the pump inlet and outlet, Pa; c1, c2——The flow velocity of the fluid at the pump inlet and outlet, m/s; z1, z2——The height of the inlet and outlet , m; ρ—liquid density, kg/m3; g—gravitational acceleration, m/s2.
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Calculation formula of fire pump head:
The head calculation of the fire pump also belongs to the category of the normal head formula calculation of the water pump, but it is necessary to calculate the working pressure of the most unfavorable point in the entire fire protection system, plus the static head of the most unfavorable point, and at the same time add the pump outlet to the most unfavorable point The sum of the along-course and local resistance drop, plus the along-course and local resistance drop of the pump suction pipeline, plus the sum of the local resistance drop of the pump, minus the pressure at the pump inlet, and taking into account the installation height of the pump, etc. The head of the fire pump can be calculated.
Fire pump head calculation formula: Hb=Hq+hd+hg+hz
Hq——Water pressure required for the most unfavorable point fire nozzle nozzle (mH2O)
hd——head loss of fire hose (mH2O)
hg——head loss of pipe network (mH2O)
hz——Height difference between the water surface of the fire pool and the most unfavorable fire hydrant (mH2O)
The flow distribution of the fire standpipe, the pressure of the nozzle of the water gun, and the calculation of the pressure loss of the hose are all the same as the calculation method of the height of the water tank.
After the height of the fire water tank and the outlet pressure of the fire water pump are calculated according to the above method, the hydraulic check calculation should also be carried out according to the most unfavorable pipe section when it is overhauled or damaged.
The indoor fire standpipe should adopt the same pipe diameter, the same fire hydrant bolt opening diameter, the same specification hose diameter and water gun caliber.
The calculation formula of fire pump head technical measure is:
H=(1.05—1.10)(∑h+Z+P)
a. 1.05—1.10: safety factor
b. ∑h pipe head loss
c.Z—Elevation difference between the fire hydrant water equipment at the most unfavorable point and the lowest water level of the fire pool
d. P—the working pressure of the fire extinguishing equipment at the most unfavorable point.
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