The Selection Steps and Key Points of Single Screw Pump

  Single screw pump is a kind of internal meshing eccentric rotary volume pump, which is mainly composed of stator with double head spiral cavity and rotor meshing with it in cavity. When the rotor rotates planet around the axis of stator in stator cavity, the sealing cavity formed between rotor and stator moves along rotor axial direction, conveying liquid evenly, continuously and constant from suction port to outlet.
  Single screw pump should be selected according to the following steps :
  1.understand the working temperature and medium viscosity characteristics, determine whether the product is applicable.
  2.Determine prime mover speed.
  3,.determine the operating conditions, flow, pressure and other requirements, the sample selection to meet the requirements of product specifications.
  4.Determine the product model, confirm the material combination, import and export location and other relevant information, combined with the product code description to determine the product model
  In the selection of single screw pump,
  1. Pressure determination of single screw pump: The maximum output pressure of single screw pump is determined according to the series of bushing, that is, the number of lead of bushing: the maximum working pressure is 0.6 MPa; Class 2 pump: maximum working pressure MPa;1.2 Class 3 pump: maximum        working pressure MPa;1.8 Class 4 pump: maximum working pressure MPa;2.4 Because of the different transport media, For media with severe wear, Please refer to our selection manual to select bushing series
  2. the selection of single screw pump speed: because of its structural characteristics, most of the single screw pump is used to transport higher viscosity liquid and liquid containing particles, so the selection of rotation number is very important. Low speed should be chosen as far as possible. At the same time, the higher the speed, the faster the abrasion resistance. For the medium with strong abrasion resistance, it is necessary to reduce the speed to prolong the life of the single screw pump.
  3. single screw pump stator rubber bushing material selection: single screw pump stator bushing is rubber product, is also a vulnerable part of single screw pump, its choice is good or bad, directly affect the life of bushing, generally normal bushing life is 3-6 months, If not selected properly, the bushing may fall off the steel pipe or rubber block. Therefore, we should understand the basic characteristics of rubber and the adaptability of rubber to various media. At present, more applications are nitrile rubber, EPDM, fluorine rubber, and food grade rubber. Among them, nitrile rubber has good oil resistance, can be used to transport oily sludge, sewage, oil and other media; EPDM has good acid and alkali resistance, so it can be used to transport enic acid, alkali and various polar chemicals; fluorine rubber has good acid and alkali resistance, more suitable for concentrated acid and high temperature conditions.
  4. material combination selection: transport different properties of the medium, according to the needs of different fixed rotor material combination.
  5. performance: generally, the performance table or characteristic curve of single screw pump is the data when 20 C of clear water is used as medium (viscosity is 1 cst), and the flow rate is different from shaft power under different viscosity.
  6. shaft seal: according to the need and conveying medium, mechanical seal and packing seal can be used, and the two structures are interchangeable. In general, for serious abrasion, high speed, municipal sludge, power plants and other high-demand units, we will choose mechanical seal. For poor fluidity and difficult maintenance, we will choose packing seal.
  7. pump driving mode: because the single screw pump is a low speed pump, the pump has more driving modes, generally there are low speed motor direct connection (6,8), gear deceleration motor drive, stepless speed motor drive and so on.
  These are the main points to be considered in the selection of single screw pump. Of course, in addition to considering the field working conditions, medium characteristics and the applicability of different material accessories, the price of single screw pump is also very different because of the different materials. Users should also cost-effective single screw pump in the budget.

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