Lift English name: water raising capacity; [range of] lift Definition 1: The difference between the water level (pressure water column height) between the pump outlet measurement section and the inlet section. Subject: Electric power (a subject); hydraulic machinery and auxiliary equipment (two subjects) Definition 2: The total energy obtained per unit weight of liquid in the pump, in meters. Subject: Coal Science and Technology (a subject); Mining Machinery Engineering (two subjects); drainage machinery (three subjects) Introduction Head The effective energy obtained by the unit weight of liquid flowing through the pump. It is an important working energy parameter of the pump, also known as the indenter. It can be expressed as an increase in the pressure head, kinetic head and potential head of the fluid, ie Important parameters The head, flow and power of the pump are important parameters for investigating the performance of the pump:
H=(p2-p1)/Ïg+(c2-c1)/2g+z2-z1
Where H is the lift, m;
P1, p2——the pressure of the liquid at the inlet and outlet of the pump, Pa;
C1, c2 - the flow rate of the fluid at the pump inlet and outlet, m / s;
Z1,z2——Import and export height, m;
Ρ——liquid density, kg/m3;
G——gravitational acceleration, m/s2.
Traffic
The flow rate of the pump is also called the water delivery volume, which refers to the volume of water that the pump delivers in a unit of time. Expressed by Q, the unit is m3/H, L/S.
2. Lift
The lift of the pump refers to the height at which the pump can lift water, usually expressed in H, and the unit is m. The lift of the centrifugal 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 head, referred to as the suction stroke; the vertical height from the center line of the pump impeller to the water surface of the outlet, that is, the pump can press the water up. The height is called the pressure head, which is called the pressure range. That is, the pump head = water lift head + pressure head. It should be pointed out that the head indicated on the nameplate refers to the head that the pump itself can produce. It does not contain the loss head caused by the frictional resistance of the pipe flow. When using a water pump, be careful not to ignore it. Otherwise, there will be no water.
3. Power
The amount of work done by the machine in unit time is called power. Usually denoted by the symbol N. Commonly used units are: kg · m / s, kilowatts, horsepower. Usually the power unit of the motor is expressed in kilowatts; the power unit of the diesel or gasoline engine is expressed in horsepower. The power transmitted by the power machine to the pump shaft, called the shaft power, can be understood as the input power of the pump. Generally speaking, the pump power refers to the shaft power.
Due to the frictional resistance of the bearing and the packing; the friction with the water when the impeller rotates; the vortex of the water flow in the pump, the backflow of the gap, the in and out, the impact of the mouth, and the like. It is inevitable that a part of the power is consumed, so it is impossible for the water pump to completely convert the power input by the power machine into effective power, wherein there is a power loss, that is, the sum of the effective power of the water pump and the power loss in the pump is the shaft power of the water pump.
4. For clean water pump, necessary NPSH
(M) Parameters are very important, especially when used in suction water supply equipment. For submersible pumps, the rated current parameter (A) is very important, especially when used in variable frequency water supply equipment.
Common water pump model code
LG-----high-rise building water pump
DL------Multi-stage vertical clean water pump
BX-------Fire-fixed special water pump
ISG------Single stage vertical pipeline pump
IS ------- single stage horizontal clean water pump
DA1-------Multi-stage horizontal clean water pump
QJ-------Submersible pump Model meaning:
Such as 40LG12-15
40-Import diameter (mm)
LG-high-rise building feed pump (high speed)
12-flow (m3/h)
15-single lift (M)
200QJ20-108/8
200--- indicates the frame number 200
QJ---Submersible pump
20—Flow rate 20m3/h
108---Head 108M
8---level 8 The basic structure of the pump: motor, coupling, pump head (body) and base (horizontal).
The main parameters of the motor: motor power (KW), speed (r / min), rated voltage (V), rated current (A).
1. What is traffic? What letter is used to indicate? How many units of measurement are used? How to convert? How to convert to weight and formula?
Answer: The volume of liquid discharged by the pump per unit time is called flow rate. The flow rate is expressed by Q. The unit of measurement is cubic meter/hour (m3/h), liter/second (l/s), L/s=3.6 m3/h=0.06. M3/min=60L/minG=QÏ G is the weight Ï is the liquid specific gravity. Example: A pump flow rate is 50 m3/h. What is the hourly weight when pumping? The specific gravity Ï of water is 1000 kg/m3.
Solution: G=QÏ=50×1000(m3/h·kg/ m3)=50000kg / h=50t/h
2. What is the head? What letter is used to indicate? What unit of measurement is used? And pressure conversion and formula?
A: The energy obtained by the unit weight liquid through the pump is called the lift. The lift of the pump, including the suction stroke, is approximately the difference between the pump outlet and the inlet pressure.
The lift is indicated by H and the unit is meters (m).
The pressure of the pump is expressed in P, the unit is Mpa (MPa), H = P / Ï. If P is 1kg / cm2, then H = (lkg / cm2) / (1000kg / m3)
H=(1kg/cm2)/(1000kg/m3)=(10000kg/m2)/1000kg/m3=10m1Mpa=10kg/c m2,H=(P2-P1)/Ï
(P2 = outlet pressure P1 = inlet pressure)
3. What is the efficiency of the pump? What is the formula?
Answer: Refers to the ratio of the effective power of the pump to the shaft power. The power of the η=Pe/P pump usually refers to the input power, that is, the power that the prime mover transmits to the pump shaft, so it is also called the shaft power, which is denoted by P. The effective power is the product of the pump head and mass flow and gravity acceleration.