The positive displacement pump is a pump that forces the liquid out of the outlet through forced pressure. Positive displacement pumps are available in various sizes and types, the choice depends on the thickness of the medium to be pumped, the pressure and capacity. The suction side is generally at the bottom with the pressure side (outlet) on the side, with or without a flange on a so-called suspension hook. The E-motor is built directly on the pump housing, generally the impeller is mounted directly on the extended motor shaft. Technically speaking, there is not much difference with the standard types of centrifugal pumps. Submersible pumps also include specific pumps for clean water, waste water, but also for cooling water and various other mediums that are pumped directly from a tank.
The pump can be divided into three parts; the bearing bracket, the fluid part and the shaft seal(s).
This is the part where a generally cast housing supporting the pump shaft and bearing is housed complete with seal. On one side there is the so-called axle journal for the coupling to a drive, on the other side the axle journal with, for example, a screw thread for the drive of a rotating element, or an axle journal with a keyway in case a (flexible) coupling is used. .
This is the part between the liquid part of the pump and the shaft. This refers to a mechanical seal such as a wear sleeve gasket (the name comes from simple square gasket rings that are stationarily mounted in a chamber in the back plate of the pump fluid part. A so-called wear sleeve is then mounted on the shaft that rotates with the shaft, the sleeve prevents the main shaft of the pump from being damaged. More commonly used nowadays are so-called "mechanical seals", which actually also have a stationary and a rotating part, but use extremely flat races that, if correctly chosen and mounted, ensure the seal to a very high degree. guarantee sealing.
There are also pumps where a magnet drive is chosen, which is actually a bearing bracket in which two magnet-filled bowls rotate that are separated by an intermediate bowl, also called a “bowler hat” because of the model. There is a slight loss of efficiency due to the "slip" between the magnets, but this gives an almost 100% guarantee of sealing if the material choices are right. These drives are relatively expensive to purchase and are mainly used if there is absolutely no emission from the product or if absolutely nothing from outside is allowed to enter the product/medium.
This is actually three parts; a pump housing in which a rotating element rotates and a back plate that seals the liquid part together with the pump housing. The parts are a pump housing with a suction and a pressure connection, in which the element rotates. The rear of the housing is closed by a back plate through which the axle comes through and the axle seal is mounted.
