Water pump rotate speed and flow rate, the relationship between water pump rotation speed and flow calculation formula

Water pump speed, flow definition:

water pump speed refers to the water pump shaft revolutions per minute. Use symbol n said. When speed is refers to the engine driven pump pumping water pump shaft revolutions per minute, with the symbol n, said unit for r/min.

also known as carrying capacity, the flow of water pump water pump discharge liquid volume per unit time or quality is the pump flow, or the pump flow refers to the water pump pumping unit of time. flow commonly used English letters Q said. flow unit is m3 / s, m3 / h and L/s, etc.

relationship and the calculation formula of water pump speed and flux:

1, the pump working point by the characteristic curve of pump characteristic curve and pipeline jointly determine:

H = Ho - pump characteristic curve SoQ ^ 2 is a concave downward decline curve

pipeline characteristic curve of the H = Z2 - Z1 + SQ ^ 2 is a concave upward curve of increasing

type: H - — head,

Ho - — Traffic is zero lift,

So - — Inside the pump friction,

Q - — flow,

Z1 - — suction pool,

Z2 - — Out of the pool water level,

S - — Pipe friction.

water pump outlet valve opening change, means that the pipeline characteristic curve of the change. When the valve's opening hours, pipeline resistance increases, S increase) , pipeline characteristic curve steepening, from the pump characteristic curve intersection to flow decreases, head greaten direction. When the valve is opening up, the opposite.

as for the change of the shaft power and efficiency should be by the characteristics of pump characteristic curve and the line on the graph. For a centrifugal pump, the shaft power with the opening of the valve become smaller and smaller.

2, in the variable frequency drive water supply equipment, the quality of frequency determines the speed of the motor and pump speed. For the same pumps, can use the proportion of water pump's law to calculate the lift under different rotational speed, flow and power. Proportional law definition: the same pumps, when the impeller diameter stays the same, and change speed, the performance of its change law.

     Q1/Q2=N1/N2,H1/H2=( N1/N2) Square,

= '(P1 / P2 N1/N2) Cube.

Q, H, p, respectively, the corresponding rotational speed N flow, head, shaft power.

3, flow rate and rotating speed in a power relationship: Q1 / Q2 = n1 n2;

head and speed into a quadratic relationship: H1 / H2 = ( n1、n2) 2

motor shaft power and speed into a third power relation: P1 / P2 = ( n1、n2) 3

by the above method can know, motor speed formula:

n = 60 f/p,

among them, n for motor synchronous speed,

f for the power supply frequency,

p for motor logarithm, the motor power supply frequency f is proportional to the speed. Such frequencies with the capacity and head and motor shaft power has the NTH power ( n = 123) Proportional relationship.

3, pump displacement and flow and the relationship between the rotational speed is as follows:

pump displacement, the theory of the relationship between flow rate and rotational speed qt = nV

n - type A hydraulic pump speed; V hydraulic pump displacement.

actual flow is refers to the hydraulic pump leakage loss, hydraulic pump in unit time

actual output of the oil volume. Because water pump leakage is found in the work, so the actual flow is less than the theoretical flow pump. Namely. q = qt - Δ q, Δ q - type A leakage.

rated flow is refers to the pump work under rated speed and rated pressure, the flow of the actual output. samples of the products or marked on the nameplate of flow to the rated flow of the water pump.

pump displacement refers to the volume of the pump shaft turn a turn out oil, with V said, the unit is mL/r. displacement depends on the hydraulic pump seal chamber geometry size, different pump, because of the different structure parameters, so the capacity is different also.

pump flow is refers to the hydraulic pump output volume of oil in unit time and commonly used q, said unit for L/min.

refers to the theory of flow without considering hydraulic pump leakage loss, pump output volume of oil in unit time, commonly used qt, said unit for L/min.

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