There are some applications that need a positive displacement pump. These pumps have several advantages they can offer and that is why they are highly used in various industries. Read on as we explain some of the top benefits of these pumps.
High viscosity
Selected air-operated piston pumps and rotary technologies handle highly viscous liquids. Their efficiency and flow rate start dropping above 500 SSU due to high friction losses. The efficiency and flow rate in rotary pumps increases with viscosity. These pumps can handle fluids with viscosity of up to several million SSU and that is why they are widely used when pumping viscous fluids.
Low and variable viscosity
PD pumps such as air-operated double diaphragm and vane pumps are often applied on thin fluids. Other fluids such as oil have viscosities that vary widely with temperature. A moderately tiny change in viscosity can have a large effect on the centrifugal efficiency with variable viscosity liquids but little effect on the efficiency of the PD pump.
Solids handling capability
Progressive cavity pumps that handle high solid content sludge in wastewater treatment plants and reciprocating pumps are used on coal slurry pipelines with solids as high as forty percent by weight. This can be a surprising PD pump feature.
Low-shear pumping needed
Liquid shear isn’t a problem in a lot of fluid applications. But it is crucial in some applications. PD pumps do great in the handling of fluids that are shear-sensitive. It is best to get a positive displacement pump on hire if you have such applications.
Multi-phase flow
It is a centrifugal pump to have a constant source of liquid but all processes don’t provide such constant sources. A gas bubble will form in the suction if there is insufficient liquid. This will cause a loss of prime. PD pumps can handle a high percentage of gas or air entrainment.
High pressure
There are a lot of sandblasting, chemical and high-pressure water-cutting applications beyond the range of centrifugal pumps. The good thing about PD pumps is that they dominate in this category.
Low flow
A flow that is above 200 psi and below 100 gpm provides great application opportunities for PD pumps.
High pressure and low flow efficiency demand combination
The previous features are the reason why you should consider using PD pumps. A PD pump is also ideal in applications where all these conditions happen simultaneously.
Seal-less pumping
Canned motor pumps and magnetic drives come with PD pump designs. The requirements are met by the designs where the pumping environment doesn’t have a shaft penetration such as diaphragm or peristaltic pumps.
Inlet conditions and self-priming
A positive displacement pump self-primes and this is a very useful feature. The ability of self-priming is a very useful feature for these pumps. It allows flexibility in the layout of the system and eliminates the need for priming systems. PD pumps are self-priming and this gives them excellent suction lift capabilities. They can draw down to near vacuum.
