Sanitary pumps are useful due to the type of properties they exhibit. There are two types of sanitary pumps in the market. One is the Positive Displacement Pump and other one is the Centrifugal pump.
To choose one out of them is not an easy task. To make the right choice between these pumps, you must first need to understand that both these pumps operate in a very different manner from each other.
Depending on the pressure, the centrifugal pump displays changing the flow. In case of a Positive Displacement pump, it shows more or less constant flow irrespective of pressure. One more difference between these two types of pumps is the impact of viscosity on the ability of the sanitary pump.
Inlet and outlet
The centrifugal sanitary pumps lose its flow when the viscosity level goes up. In the case of the Positive Displacement pump, the flow increases with the increase in the viscosity level. The primary reason behind higher levels of viscosity liquids is to fill the sanitary pump clearances and to introduce a higher level of volumetric efficiency.
Changes in pressure
Pressure changes do not have a major impact on the Positive Displacement pump but have a big impact on the centrifugal. With centrifugal pumps the efficiency goes down as the viscosity rises due to increased frictional losses inside the pump.
In what forms are sanitary positive displacement pumps available in the market?
You may find these pumps in a wide range of configurations that includes diaphragm, piston, rotary piston, twin screw, progressive cavity and lobe, to name a few.
So, which one would be the best choice?
A Positive Displacement pump has the ability to produce more amount of pressure as compared to the centrifugal pump. This pump operates at a very low speed as compared to the centrifugal pump. It will then have an impact on the seal life. The seal of a positive displacement pump lasts a lot longer as compared to the seal of its counterpart.
These pumps are normally preferred for low flow rate or high-pressure applications. There are a few cases where sanitary Positive Displacement pumps can also be used in the form of a metering device which is not possible with a centrifugal pump.
So, these are the differences between a centrifugal and a PD pump. Hope this information will help you find an ideal pump for your use.