Selection principle of water pump

The principle of selection of 1. pumps

(1) meeting the principle of process parameters

Flow:

The 1. process requires the rated, minimum and maximum three kinds of flow of the pump, and the pump should be based on the maximum flow rate.

2. when the maximum flow is not given, it is usually based on the 1.1 times of the rated flow.

Lift:

1. the lift value of the pump should be paid attention to the minimum suction level and the highest liquid height, and the allowance should be left at the same time.

2. the rated lift of the general selection pump is 1.05~1.1 times the required lift of the device

Temperature:

The maximum temperature should be based on the rated, minimum and maximum temperature of the pump inlet medium during the process of giving the process.

Pressure:

The pressure of the inlet and outlet pressure is the pressure of the pump in and out of the flange. The size of the inlet and outlet pressure affects the endurance of the shell, the shaft seal and the selection of the cooling device.

Device cavitation allowance:

According to the characteristics of the process and the arrangement of equipment and equipment, the initial value of the necessary cavitation allowance is put forward.  According to the cavitation curve of the selected pump, the necessary cavitation allowance and the installation height of the equipment are determined, and the cavitation allowance is calculated.

Note: if the transportation is viscous liquid or the sewage with particles, the process parameters should be converted into the parameters of clean water to choose the pump.

(2) the principle of satisfying the performance of the conveyed liquid

Corrosive liquid

1. pump overflow parts and shaft seal shall meet the corrosive (PH) requirements of the conveyed liquid.

2. the liquid overcurrent components with strong corrosiveness are made of nonmetallic materials, such as ceramic FRP, F46, graphite and so on.

3. when corrosive liquids are still carrying particles, the overcurrent parts should be made of corrosion resistant and wear-resistant metal corrosion resistant materials, such as high silicon cast iron, stainless steel, high nickel alloy, titanium alloy and so on.

4. under normal circumstances, the corrosion resistant metal pump has better wear resistance, pressure resistance and high temperature resistance than non-metal pump, and the corrosion resistance of non-metal pump is better than that of metal pump.

Leaking liquids are not allowed

For toxic, flammable, explosive and odorous liquids, valuable media, aseptic transportation and vacuum transportation shall comply with the principle of no leakage. The sealing part of the pump shall be safe or reliable, or the shielding pump, magnetic pump, diaphragm pump and so on shall be selected.

A liquid containing a fixed particle

1. according to the size of the fixed particles in the conveyed liquid and the proportion of the content, different overcurrent components are selected.

2. when the liquid containing fixed particles is larger and more, the overcurrent pump, such as a swirling pump and a single channel impeller pump, can be selected for the non blocking design.

3. material for selecting overcurrent components according to the hardness, content and corrosiveness of the fixtures contained in the conveyed liquid

Long fiber liquid containing liquid

1. the overflow component uses a tearing and cutting structure to ensure that the impeller is not entangled with long fibers.

2. consider the mechanical properties of the motor (overload capacity, etc.)

High temperature and high pressure liquid

1. selection of high temperature and high pressure material for overflow parts

2. the requirements for the mechanical strength and the thermal expansion of the overcurrent components under high temperature and high pressure are considered.

3. selection of shaft seal and cooling device with high temperature and high pressure

Viscous liquid

1. the rotor pump, such as reciprocating pump and spiral pump, can be used.

2. high viscosity liquid with high viscosity, high viscosity spiral pump, gear pump and high viscosity reciprocating pump

(3) the principle of meeting the operating environment of the pump

Installation position

1. the influence of the altitude of the geographical position;

2. according to the conditions of installation, horizontal, vertical, single and multistage are selected.

3., the pump is installed indoors, outdoors, on the ground or under the liquid. If the liquid is a single pump head or diving with the motor, we should also consider the depth of the liquid and the depth of the diving.

The influence of vibration and impact on the installation of 4. pump

environment condition

1. ambient temperature: the pump may be used at temperatures below -20 degrees. We should consider the cold crispness of the pump and adopt low temperature resistant materials. The structure of the pump should be cylindrical double shell centrifugal pumps.

2. environment noise: for the low noise of the pump, we should choose the low noise design of the sliding bearing structure and the hydraulic power, and use the low noise motor.

3. relative humidity: in the use of high humidity environment, to consider the corrosion of the pump, should take antirust measures. The protection level of the motor is also considered.

4. atmospheric pressure and atmospheric corrosion.

Power grid conditions

1. the frequency of the power grid (the case of 60Hz frequency abroad);

2. power grid capacity is sufficient;

3. power grid voltage three phase (380V), single phase (220V), or different voltage (including high voltage above 660V)

The range of the change of the power supply voltage;

4. AC and DC power supply;

5. the voltage drop of the distance between the use of the power supply and the use of the pump (long distance cable)

Division of dangerous areas

1. consider whether the pump is allowed to run, run, drop and leak, and whether the liquid is flammable and explosive.

2., the selection of the power source of the pump and the explosion-proof level of the motor. For installing the explosive gas area, we should match the explosion-proof motor according to the grade of the explosion area.

In addition to the above three principles, the efficiency of the pump (energy saving), quality, installation and maintenance and price (cost) and other economic indicators should be considered comprehensively. Special pumps should be selected for special requirements, such as vacuum transport, high temperature transport, low temperature transport and so on.