Pump selection process attention

First, list the basic data:

1. Characteristics of the medium: medium name, specific gravity, viscosity, corrosivity, toxicity, etc.

2. Diameter and content (mass or volume percentage) of solid particles contained in the medium

3. Medium temperature: (°C)

4, the required flow (昕科泵业)

Usually industrial pumps can ignore the amount of leakage in the pipeline system in the skill flow pump, but it is necessary for the pump to think about the impact on the flow when the skill changes. Agricultural pumps If it is to use open channels to transport water, it is necessary to consider leakage and evaporation.

5. Pressure: Pressure drop in the pressure piping system of the suction basin pressure draining tank (head loss)

6. Pipeline system data (pipe diameter, length, pipe attachment type and number of sinks to the geometric elevation of the pressure tank, etc.) If necessary, the equipment characteristic curve should also be made. When planning the installation of the pipeline, the following items should be noted:

A. Reasonable selection of pipe diameter Pipe diameter is large Under the same flow rate, liquid flow velocity small resistance loss is small but the price is high. The pipe diameter is small, which will cause the resistance loss to increase sharply. Therefore, it should be concluded from the perspective of skills and economy.

B. The discharge pipe and its pipe joints should be considered to be able to withstand the maximum pressure

C. Pipeline placement should be as close as possible to the straight pipe. Minimize the attachments in the pipe and minimize the length of the pipe. The bend radius of the time-division elbow should be 3 to 5 times the diameter of the pipe. The view point may be greater than 90 °C.

D. It is necessary to install a valve (ball valve or shut-off valve, etc.) and a check valve to regulate the working condition of the pump. The check valve prevents the pump from rotating and prevents the pump from hitting the water hammer when the liquid flows backward. (Infinite reverse pressure occurs when the liquid flows back to damage the pump)

Second, determine the flow head

Determination of traffic

a. If the minimum, normal, and maximum flow rates have been given in production skills, think at maximum flow.

b. If only the normal flow rate is given in the production skill, it should be considered that there is a certain margin. The large flow rate of ns>100 is low. The unbalanced pump flow balance is 5%. The small flow high lift pump flow balance of ns>50 Take 10% 50 ≤ ns ≤ 100 pump flow margin is also taken 5% for poor quality and poor operating conditions, pump flow margin should be 10%

c. If the fundamental data is only converted to volume flow, the component flow should be converted.

Pay attention to matters

1, device leakage protector

The leakage protector is also called a life-saving device, and its function can be understood from the words "life-saving device". Because the submersible pump operates underwater, simple leakage creates a loss of electrical energy and even an electric shock. If the leakage protector is installed, only the leakage current value of the submersible pump exceeds the operating current value of the leakage protector (usually does not exceed 30 mA), and the leakage protector blocks the power supply of the submersible pump to prevent leakage of electric power and safety.

2, the power supply voltage is abnormally booted

In rural areas, because the low-voltage power supply line is relatively long, the end voltage of the line is too low. When the phase voltage is lower than 198 volts and the line voltage is lower than 342 volts, the motor speed of the submersible pump is reduced. When the 70% of the additional speed is not reached, the centrifugal switch will be turned off, and the starting winding will be energized for a long time to generate heat and even burn out. Windings and capacitors. Conversely, a voltage that is too high causes the motor to overheat and burn out the windings. Therefore, in the operation of the submersible pump, it is necessary for the operator to investigate the value of the power supply voltage at any time. If it is less than 10% of the extra voltage and higher than 10% of the extra voltage, the motor should be stopped, the factors should be found and the fault should be eliminated.

3, prevent frequency switch

Do not switch the submersible pump frequently. This is because the recirculation occurs when the electric pump is stopped. If it is turned on immediately, the motor load will be started, causing the starting current to be too large to burn the winding. Because the current is very large when starting, frequent starts will also burn the submersible pump motor windings.

4, Do not let the submersible pump long-time overload operation

In order to prevent the submersible pump from overloading for a long time, do not pump the water with a large amount of sand and check whether the current value is specified on the nameplate. If the current is too large, stop it. In addition, the dehydration operation of the electric pump should not be too long to avoid overheating the motor and burning it.

5, the motor's rotation direction should be accurate

The direction of rotation of the motor should be clarified. Nowadays, there are many types of submersible pumps that can discharge water during forward and reverse rotation, but the amount of water flowing out during rotation is small and the current is large. The long rotation time will damage the motor winding.

6. Insulation resistance request of the cable line device and submersible pump of Yankee Pump Industry

When installing the submersible pump, the cable should be overhead and the power cord should not be too long. Do not force the cable when the submersible pump is launched or raised to avoid causing the power cord to break. Do not sink into the mud when the submersible pump is working, otherwise it will cause the motor to dissipate heat and burn the motor windings. When the device is installed, the insulation resistance of the motor should not be less than 0.5 megohm.

7, diligently check and see problems found in time to correct

Usually, you should always check the motor. If you find cracks in the lower cover, damage or failure of the rubber seal ring, you should replace or correct it in time to prevent water from entering the submersible pump.