Stainless steel screw pump G type

1、 Stainless steelscrew pump(Sanitary grade)）Description

Sanitary screw pump is a new type of pump that works according to the principle of rotary meshing displacement. The main working components are eccentric screw (rotor) and fixed liner (stator).

Due to the special geometric shape of these two components, they form separate sealed chambers, and the medium flows uniformly in the axial direction. The internal flow velocity is low, the volume remains constant, and the pressure is stable, so there will be no vortex or agitation. The output pressure of each stage pump is 0.6MPa, with a head of 60m (clean water), suitable for conveying medium temperatures below 80 ℃ (special requirements can reach 150 ℃).

Due to the selection of multiple elastic materials for the stator, this pump has characteristics that general pump types cannot handle for transporting high viscosity fluids and media containing hard suspended particles or fiber media. Its flow rate is proportional to the rotational speed.

Transmission can be achieved directly through couplings, or through devices such as variable speed motors, V-belts, gearboxes, etc.

This type of pump has few parts, compact structure, small volume, and easy maintenance. The rotor and stator are the vulnerable parts of this pump, and the structure is simple and easy to assemble and disassemble.

2、 Advantages of sanitary screw pump:
1) Wide range of pressure and flow. The pressure is about 3.4-340 kgf/cm2, and the flow rate can reach 18600 cm3/min;
2) The types and viscosity range of liquids transported are wide;
3) Due to the low inertia force of the rotating components inside the pump, a high rotational speed can be used;
4) Good inhalation performance and self-priming ability;
5) Uniform and continuous flow, low vibration, and low noise;
6) Compared with other rotary pumps, it is less sensitive to incoming gases and pollutants;
7) The structure is solid and easy to install and maintain.
The disadvantage of sanitary screw pumps is that the processing and assembly requirements for screws are relatively high; The performance of the pump is sensitive to changes in the viscosity of the liquid.

3、 Sanitary screw pump structure:
It is mainly composed of a liner (pump cylinder) fixed in the pump body, an active screw inserted in the pump cylinder, and two driven screws engaged with it. Three interlocking screws form a sealed chamber in the pump cylinder according to each lead, creating a seal between the suction and discharge ports.
When the pump is working, due to the symmetrical meshing between the two driven screws and the driving screw, the radial force acting on the driving screw is completely balanced, and the driving screw does not bear bending loads. The radial force acting on the driven screw is supported along its entire length by the pump cylinder liner, so there is no need to install additional bearings at the outer end, and it basically does not bear bending loads. During operation, a layer of oil film is formed between the outer surface of the screw and the inner wall of the pump cylinder, which can prevent direct contact between metals and greatly reduce the wear of the screw tooth surface.
When a stainless steel single screw pump is in operation, the suction and discharge pressures of the liquid act on both ends, thus generating axial thrust on the screw. For small pumps with a pressure difference less than 10 kgf/cm2, thrust bearings can be used. In addition, high-pressure oil is introduced into the bottom of each screw shaft sleeve through the central oil hole of the active screw, thereby generating a balanced thrust opposite to the axial thrust direction at the lower end of the screw.
Like other positive displacement pumps, when the discharge port of the pump is completely closed, the pressure inside the pump will rise to a dangerous level that could damage the pump or overload the motor. So, a safety valve must be installed at the suction and discharge ports of the pump.
The shaft seal of stainless steel single screw pump usually adopts mechanical shaft seal, and can take different forms according to the working pressure.

4、 Working principle of sanitary screw pump:
Sanitary screw pumps use the rotation of screws to suction and discharge liquids. Due to the mutual meshing of the screws and the tight fit between the screws and the inner wall of the liner, one or more sealed spaces will be separated between the suction and discharge ports of the pump. As the screw rotates and meshes, these sealed spaces are continuously formed at the suction end of the pump, sealing the liquid in the suction chamber and continuously moving from the suction chamber along the screw axis to the discharge end, continuously discharging the liquid enclosed in each space, just like a nut being constantly pushed forward when the thread rotates. This is the case when a vertical screw pump works, the liquid is sucked in and enters the sealed space surrounded by the thread and pump housing. When the active screw rotates, the sealing volume of the screw pump increases the screw pump pressure under the compression of the thread and moves along the axial direction. Due to the constant rotation of the screw, the liquid outflow flow rate is also uniform.

5、 Technical parameters of sanitary screw pump:
Flow rate: 0-150m3/h;
Head: 0-180m;
Power: 0.75-37kw;
Speed: 500-960r/min;
Caliber: 20-135mm;
Temperature: -15-200 ℃.

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