What is the difference between single screw pump and twin screw pump? Which is better?

What is the difference between single screw pump and twin screw pump?

Screw pump can be divided into single-screw pump, double-screw pump and three-screw pump according to the number of internal screws. Compared with single-screw pump and double-screw pump, the main differences are as follows:

1. Structural differences:

Single-screw pump: there is only one screw shaft. Single-head male screw rotor rotates eccentrically in the special double-head female screw stator (the stator is soft). It can swing back and forth along the center line of the pump and always keep mesh with the stator.

Twin screw pump: There are two screw shafts of the same size, one driving shaft and the driven shaft, which are driven by gears to achieve synchronous rotation.

2. Characteristic difference:

Single-screw pump, whose stator material will limit its working temperature, can transport liquid containing solid particles, and can also be used to transport all kinds of liquid with viscosity. It is also very suitable for conveying liquid with high viscosity and non-Newtonian.

Twin screw pump: insensitive to impurities; The clearance between screw and pump body and screw is 0.05~0.15 mm, so the wear is small and the service life is long; The stuffing box is only subject to suction pressure, Therefore, its leakage is small.

3. Performance parameter difference:

Single screw pump: flow up to 150m ³/ h. The pressure can reach 20MPa. 

Twin-screw pump: the pressure is usually about 1.4MPa. For viscous liquid below 7MPa, the low viscosity liquid can reach 3MPa, and the flow rate is usually 6~600m/h, and 1600m ³/ H, and the liquid viscosity shall not be greater than 1500m ㎡/s.

4. Application difference:

Single-screw pump: can be used to transport chocolate paste, starch paste, molasses, pulp, clay, mud, tar, paint, grease, paraffin, etc.

Twin screw pump: used for transportation of lubricating oil, grease, crude oil, tar, fuel oil and other high viscosity oil.

Which is better, single screw pump or twin screw pump?

Compared with the twin screw pump, the single screw pump has its own advantages and disadvantages, which is not necessarily better. The main reason is to select the appropriate screw pump according to the medium to be transported and the application situation:

1. Single-screw pump has the lowest volumetric efficiency and pressure resistance, but the transmission medium has the highest inclusivity. It is suitable for conveying media with particles, viscous slurry, etc., and the flow and pressure do not need to be too large.

2. The volumetric efficiency of the twin-screw pump is slightly higher, but the pressure is high. If the viscosity is low, the efficiency will decrease quickly, the range of the medium to be transported is also wide, the displacement is also large, and it is sensitive to the particle size. It is generally suitable for large flow of high-viscosity medium, such as fuel oil and crude oil, which requires large flow and high pressure, and is generally used as a delivery pump.