Three screw pump selection skills
Although the three-screw pump has many advantages, if it is not properly selected, it not only can not get a satisfactory operation result, but also causes noise and vibration of the pump and even seriously damages internal parts of the pump so that the pump system can not work normally. Therefore, Selection of personnel should be cautious and careful consideration, a reasonable selection, if necessary, should I plant technical advice.
Three screw pump selection, to be as detailed as possible to understand the conditions of the pump, in addition to the operating parameters, such as flow, pressure needs to be clear, the characteristics of the transmission medium such as media corrosivity, gas content, solid solution containing the ratio And the size of the solid particles, as well as the medium temperature, viscosity, specific gravity, corrosive materials such as pumping equipment and suction conditions, installation conditions should be understood, according to our experience, three screw pump selection should pay attention to the following point:
Pump speed selection
1.1 to determine the transmission medium viscosity and pump speed range:
When transporting high-viscosity media, the pump should be selected low speed, if the viscosity is low, the corresponding choice of high speed:
Medium viscosity> 20 ° E, for large size pumps (main bar OD 60 mm and over) at 970 rpm or 720 rpm, lower viscosity if viscosity is higher (viscosity> 80 ° E) , Recommended 200-500rpm;
For small pump sizes, medium speeds> 14 ° F or 970 rpm for medium viscosities> 20 ° E and 300-600 rpm for lower viscosities (> 80 ° E)
1.2 As the pump speed is higher, the same performance parameters, the smaller the pump size, but because of high speed, high friction power, the pump wear large, short life, if the lubrication of the transmission medium is relatively poor or contains Trace impurities, should choose a lower speed, so that the pump to maintain a longer life, recommended below 1450rpm.
2. The choice of structure can be based on the installation and use of the pump reference three screw pump series and type to carry out, in principle:
2.1 Transport lubricants, the temperature below 80 ° C select the built-in bearing structure of the pump;
2.2 When the temperature exceeds 80 ° C or transmission medium lubrication is poor, select the external bearing structure of the pump;
2.3 conveying poor mobility, higher viscosity of the medium or the need to transport the medium for heating or insulation, select double pump structure of the pump;
2.4 High temperature conveying, should choose the pump made of high temperature resistant materials, please contact with our factory.
3. Pump material combination of options:
See the material combination.
4. Pump suction capacity can be found in our factory sample NPSHr or [HS] value.
5. Matching motor matching
Pump selection is determined, according to the sample data can be found in the pump shaft power N, the shaft power coupled with a certain power reserve, as a basis for optional motor, the general motor power Nm should be not less than the pump shaft power N times With the power reserve coefficient K after the value obtained, K value can refer to the following table value:
N (KW) N <5 5 10 N> 50
K 1.25 1.2 1.15 1.1
In addition, the election pump often also provided by the sample pump performance parameters are in the form of a specific form of viscosity or speed curve is given, the performance of the required value of the pump sometimes can not be read directly, then follow the following principles Rough estimate, for more accurate data can consult professionals.
Three screw pump flow, pressure in the same speed, viscosity is approximately linear relationship, the higher the pressure, the smaller the flow.
The same viscosity, pressure, pump flow and speed is approximately proportional to.
The same speed, viscosity, shaft power and pressure is approximately proportional.
The same viscosity, pressure, shaft power and speed is approximately proportional.
As the viscosity increases, both flow and shaft power increase, but because of the complex relationship between them, consult a specialist if necessary.
As long as the proper selection, maintenance and reasonable, three screw pump can ensure satisfactory operation.
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