Pump head and pressure conversion
In physics, pressure refers to the force acting vertically on the surface of an object. The force-bearing object is the supporting surface of the object, the point of action is on the contact surface, and the direction is perpendicular to the contact surface. When the force-bearing object is a horizontal plane, pressure (F) = weight [Please note that it is different from mass (G), G= Mg]. In this case, when the stressed object is a horizontal plane, pressure (F) = weight [Please note that it is different from mass (G), G=Mg]. The pressure of the water pump is expressed by P, the unit is Mpa (Mega Pa)
1Mpa=10kg/c m2, H=(P2-P1)/ρ (P2=outlet pressure P1=inlet pressure)
The conversion relations of several common pressure units in engineering are as follows:
1MPa=106Pa≈145psi≈10.2kgf/cm²
1kgf/cm²=98.067kPa≈98kPa
1psi (1bf/in²)=6.8948kPa≈6.9kPa
1mmH2O=9.8067Pa≈9.8Pa
The head of a water pump refers to the height at which the water pump can lift water or the effective energy obtained after the unit weight of liquid flows through the pump. It is an important performance parameter of the pump, also known as the pressure head. The head of the pump, including the suction stroke, is approximately equal to the pressure difference between the outlet and inlet of the pump. Expressed by H, the unit is meter (m). The head of the centrifugal water pump is based on the center line of the impeller and consists of two parts. The vertical height from the center line of the pump impeller to the water surface of the water source, that is, the height at which the pump can suck up the water, is called the suction lift, referred to as the suction lift; the vertical height from the center line of the pump impeller to the water surface of the outlet pool, that is, the pump can press the water up. The height of is called pressure head, or pressure range for short.
H=P/ρ. If P is 1kg/cm2, then H=(lkg/ cm2)/(1000kg/ m3) H=(1kg/ cm2)/(1000kg/m3)=(10000kg/m2)/1000 Kg/m3=10m
That is, pump head = suction head + pressurized water head. It should be pointed out that the head marked on the nameplate refers to the head that the pump itself can generate, and it does not include the loss head caused by the frictional resistance of the pipeline water flow. When choosing a water pump, be careful not to ignore it. Otherwise, there will be no water.
Pump head = net head + 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 clean water tank and sending it to a high water tank. The net head refers to the height difference between the suction inlet of the clean water tank and the high water tank.
The flow rate of the water pump is also called the water delivery volume, which refers to the volume of water delivered by the water pump per unit time. Expressed by Q, the unit is m3/H, L/S.
Pump efficiency: refers to the ratio of the effective power of the pump to the shaft power. η=Pe/P The power of a pump usually refers to the input power, that is, the power transmitted from the prime mover to the pump shaft, so it is also called shaft power, which is represented by P. The effective power is: the product of the pump's head, mass flow and gravitational acceleration.
The relationship between pump lift and pressure
1. The formula for the relationship between head and pressure: H=(p2-p1)/ρg+(v2²-v1²)/2g+z2-z1
2. From the above formula, it can be concluded that the pressure of 1MPa is approximately equal to the head of 100m, and the pressure of 1kg of water is 0.1MPa, that is, 1Mpa=100m=10kg.
Therefore, a submersible pump with a head of 60 meters is driven into a pressure pipe with a relative height of 35 meters, and a pressure of up to 10 kilograms is formed in the pressure tank.
In the formula of the relationship between head and pressure:
H stands for: head, the unit is m;
p1, p2 represent: the pressure of the liquid at the inlet and outlet of the pump, the unit is Pa;
v1, v2 represent: the flow velocity of the fluid at the inlet and outlet of the pump, the unit is m/s;
z1, z2 represent: the height of the entrance and exit, the unit is m;
ρ stands for: the density of the liquid, the unit is kg/m³;
g stands for: acceleration of gravity, the unit is m/s².
The head of a water pump refers to the height at which the water pump can lift water.
Calculation result of pump pressure:
From the above formula, it can be concluded that the pressure of 1MPa is approximately equal to the head of 100m, and the pressure of 1kg of water is 0.1MPa, that is, 1Mpa=100m=10kg.
Therefore, a submersible pump with a head of 60 meters is driven into a pressure pipe with a relative height of 35 meters, and a pressure of up to 10 kilograms is formed in the pressure tank.
