Working principle of DESMI ROTAN gear pump

DESMI ROTAN gear pump working principle

In terms of terminology, the DESMI ROTAN gear pump is also called a positive displacement device, 

which is like a piston in a cylinder. When one tooth enters the fluid space of the other, the liquid is

 mechanically squeezed out. Because liquid is incompressible, the liquid and teeth cannot occupy 

the same space at the same time, so the liquid is eliminated. Due to the continuous meshing of teeth, 

this phenomenon occurs continuously, so a continuous removal amount is provided at the outlet of

 the pump. The discharge amount is the same for each rotation of the pump. As the drive shaft rotates

 continuously, the pump also discharges fluid continuously.

The structure of the DESMI ROTAN gear pump is very simple, that is, its most basic form is that two gears

 of the same size mesh and rotate in a tightly fitted shell. The interior of this shell is similar to the shape 

of the shape of the "8". The two gears are installed inside, and the outer diameter and sides of the gear

 are closely matched with the shell. The material from the extruder enters the middle of the two gears 

at the suction port and fills this space, moves along the shell as the teeth rotate, and finally discharges 

when the two teeth engage.

There are actually limitations on the rotational speed of a pump, which mainly depends on the process 

fluid. If the oil is being conveyed, the pump can rotate at a very high speed, but when the fluid is a high 

viscosity polymer melt, this limitation will be greatly reduced. It is very important to push high viscous

 fluid into the two-tooth space on one side of the suction inlet. If this space is not filled, the pump cannot

 discharge the accurate flow rate, so the PV value (pressure × flow rate) is also another limiting factor 

and is a process variable. Due to these limitations, gear pump manufacturers will provide a range of products, 

namely, different specifications and displacements (the amount discharged per revolution per week). These 

pumps will be combined with specific application processes to optimize system capabilities and price.

The flow rate of the DESMI ROTAN gear pump is directly related to the speed of the pump. In fact, there 

is a small amount of fluid loss in the pump, which prevents the pump from operating efficiency to 100%, 

because these fluids are used to lubricate the bearings and gear sides, and the pump body cannot be 

matched without gaps, so the fluid cannot be discharged 100% from the outlet, so a small amount of 

fluid loss is inevitable. However, the pump can still operate well, and for most extruded materials, it can 

still achieve an efficiency of 93% to 98%. For fluids whose viscosity or density varies in the process, this

 pump will not be affected much. If there is a damper, such as putting a filter or a limiter on the outlet 

side, the pump pushes fluid through them. If this damper changes during operation, i.e. if the filter 

becomes dirty, blocked, or the back pressure of the limiter is raised, the pump will still maintain a constant 

flow until it reaches the mechanical limit of the weakest component in the device (usually equipped with a torque limiter).