High-Pressure Pumps: Deciding Between A Centrifugal Pump And A Positive Displacement Pump

The most common high-pressure pumps are centrifugal pumps and positive displacement pumps. Though both perform the same function, they differ in efficiency, operating conditions, and type of fluids they pump.

As a result, if you intend to buy a high-pressure pump, it is advisable to compare and contrast both types to determine which one meets your needs. Thus, here are two factors to consider when choosing between centrifugal and positive displacement high-pressure pumps. 

Fluid Viscosity

When it comes to centrifugal high-pressure pumps, viscosity affects the efficiency of the pump. In most cases, a centrifugal pump will lose efficiency as the viscosity of the fluid rises. The above scenario occurs because centrifugal pumps convert rotational energy into kinetic energy. Thus, the more viscous a fluid is, the less rotational energy the centrifugal pump can create. Therefore, the fluid will have low kinetic energy, which results in low fluid pressure. 

However, the efficiency of a positive displacement pump doesn't reduce with viscosity. On the contrary, the efficiency of this pump tends to increase with the fluid's viscosity. The above scenario occurs because positive displacement pumps pump fluid by pressuring. Hence, the more viscous the fluid is, the higher the pumping pressure a positive displacement pump produces. 

Hence, if you intend to buy a high-pressure pump for pumping viscous fluids, opt for a positive displacement pump instead of a centrifugal pump. 

Performance Consistency

The pressure produced by a centrifugal pump depends on the rotational force inside the pump. Hence, when it comes to centrifugal pumps, speed determines the pressure. Thus, a centrifugal pump's performance varies because friction and viscosity affect rotational force. Hence, achieving consistent performance from a centrifugal pump is challenging. 

On the other hand, in a positive displacement pump, the pressure in the pump determines the speed and rate of flow. So, provided you maintain the pressure in the pump at a constant level, the rate of flow will remain constant. It is easier to achieve performance consistency with a positive displacement pump than with a centrifugal pump. 

Besides, you need to apply fluid treatment and pump throttling to maintain the performance of a centrifugal pump. But, this is not the case with a positive displacement pump. Thus, it is also less expensive for you to maintain performance consistency with a positive displacement pump than it is with a centrifugal pump. 

Thus, if performance consistency is a key factor, consider buying a positive displacement high-pressure pump.