--- title: "Centrifugal Pump vs Positive Displacement Pump: Which Do You Need?" date: 2026-08-04T02:41:52Z modified: 2026-08-25T03:47:29Z permalink: "https://www.defucc.com/blog/buying-guide/centrifugal-pump-vs-positive-displacement-pump/" type: post status: publish excerpt: "" wpid: 2835 categories: - buying guide featured_image: "https://www.defucc.com/wp-content/uploads/2026/08/image-81.webp" featured_image_alt: Centrifugal Pump vs Positive Displacement Pump timestamp: 2026-08-25T03:47:29Z tags: - buying guide --- ## **Quick Answer:** Choose a centrifugal pump for relatively low-viscosity liquids when smooth, continuous flow is the priority. Choose a positive displacement pump when the fluid is viscous, contains solids or needs controlled transfer at changing system pressure. DEFUCC manufactures both centrifugal and air-operated diaphragm pump ranges. The key difference is how each pump moves liquid, which affects flow behavior, pressure response and fluid compatibility. ## **What Is the Main Difference Between Centrifugal and Positive Displacement Pumps?** A [centrifugal pump](https://www.defucc.com/wp-content/uploads/wp-mfa-exports/post/diaphragm-pump-vs-centrifugal-pump-industrial-needs.md) adds velocity to liquid through a rotating element, while a positive displacement pump traps and moves a defined volume during each operating cycle. That difference changes how each pump responds to system resistance. | **Selection Factor** | **Centrifugal Pump** | **Positive Displacement Pump** | | --- | --- | --- | | Flow behavior | Changes noticeably with system head | More consistent per cycle | | Best fluid range | Commonly low to moderate viscosity | Often better for viscous fluids | | Typical flow style | Smooth and continuous | Pulsating or cyclic depending on design | | Pressure response | Flow decreases as head rises | Can continue building pressure against resistance | | Solids capability | Depends strongly on pump design | Some designs handle solids well | | Priming | Depends on pump type | Many designs are self-priming | | Common use | Water, circulation, drainage, process transfer | Chemicals, sludge, coatings, viscous fluids | Neither pump principle is universally better. The fluid and process should determine the selection. ![Displacement Pump](https://www.defucc.com/wp-content/uploads/2026/08/image-82-1200x800.webp) ## **When Should You Choose a Centrifugal Pump?** Choose a centrifugal pump when the process requires continuous movement of a relatively free-flowing liquid at moderate to high flow. Common applications include: **·** Water circulation **·** Irrigation **·** Municipal water transfer **·** Cooling systems **·** [Drainage](https://www.defucc.com/wp-content/uploads/wp-mfa-exports/post/drainage-vs-dewatering.md) **·** Chemical circulation **·** General industrial transfer ### **Why Are Centrifugal Pumps Common for Water?** Water has relatively low viscosity, so it responds well to the continuous rotational action of a centrifugal pump. Centrifugal pumps can also be built across a wide range of flow and head requirements. For corrosive process liquids, an [IHF chemical centrifugal pump](https://www.defucc.com/product/ihf-chemical-centrifugal-catalog/) uses a fluoroplastic-lined construction rather than a conventional unlined water-pump structure. DEFUCC lists a maximum flow of 400 m³/h and maximum head of 80 m for the series. That example also shows why “centrifugal” does not automatically mean “water only.” Material construction can adapt the basic pump principle to other liquids. ### **What Happens When System Resistance Increases?** Centrifugal pump flow generally decreases as the system head rises. This relationship appears on the pump performance curve. If pipe friction or discharge pressure increases, the operating point moves along that curve. The pump does not normally continue delivering the same flow regardless of pressure. This behavior makes pump-curve review important during centrifugal pump selection. IHF Chemical Centrifugal Pump High-performance solution for transferring clean, corrosive, or chemically aggressive liquids with maximum safety and resistance. [Explore Chemical Pumps](https://www.defucc.com/product/ihf-chemical-centrifugal-catalog/) [ ![DEFUC IHF Chemical Centrifugal Pump](https://www.defucc.com/wp-content/uploads/2025/02/IHF-Chemical-Centrifugal-Catalog.webp) ](https://www.defucc.com/product/ihf-chemical-centrifugal-catalog/) ## **When Should You Choose a Positive Displacement Pump?** Choose a positive displacement pump when the application involves viscosity, solids, chemical handling or a need to move fluid independently of the centrifugal flow-head relationship. Positive displacement pumps move liquid by repeatedly trapping a volume and forcing it toward the discharge. ### **Where Do Air-Operated Diaphragm Pumps Fit?** An air-operated double [diaphragm pump](https://www.defucc.com/wp-content/uploads/wp-mfa-exports/post/how-does-a-diaphragm-pump-work.md), or AODD pump, is one type of positive displacement pump. Two flexible diaphragms move back and forth while check valves control inlet and discharge flow. DEFUCC’s own diaphragm-pump guidance defines diaphragm pumps as positive displacement pumps. An [AOK air diaphragm pump](https://www.defucc.com/product/aok-series-air-diaphragm-pump/) can handle applications involving chemicals, wastewater and other industrial fluids. DEFUCC lists flow up to 63.6 m³/h, head up to 84 m and solids passage up to 9.4 mm for the range. ### **Why Can Positive Displacement Pumps Handle Viscous Fluids Better?** A positive displacement mechanism physically moves a trapped amount of fluid rather than depending primarily on liquid velocity. This can make it more suitable for fluids such as: **·** Sludge **·** Paint **·** Adhesives **·** Oils **·** Concentrated chemicals **·** Viscous process liquids Actual performance still changes with viscosity, suction conditions and the specific pump design. ## **How Does Viscosity Affect Centrifugal and Positive Displacement Pumps?** Increasing viscosity generally creates a bigger performance penalty for centrifugal pumps than for many positive displacement designs. A thick liquid resists the high-velocity flow mechanism used by centrifugal pumps. ### **What Happens to a Centrifugal Pump With Thicker Fluid?** Higher viscosity can reduce: **·** Flow **·** Head **·** Hydraulic efficiency It may also increase the power needed for the application. This does not mean centrifugal pumps cannot handle any viscous liquid. The acceptable range depends on the pump, speed and fluid properties. ### **Why Can an AODD Pump Be Better for Thick Liquids?** An AODD pump relies on diaphragm displacement rather than an impeller creating high fluid velocity. DEFUCC’s chemical-pump application information identifies AODD pumps for solids-containing, shear-sensitive and high-viscosity fluid duties, while centrifugal pumps are positioned more toward higher-flow continuous processing. The required air supply still needs to be sized for the actual fluid and flow. ## **Which Pump Is Better for Solids?** Neither category can be selected from the word “solids” alone. Particle size, concentration and abrasiveness matter. Some centrifugal pumps have large passages for [sewage](https://www.defucc.com/wp-content/uploads/wp-mfa-exports/page/sewage-pump.md) or slurry. Some positive displacement pumps can also handle suspended particles effectively. ### **When Can a Centrifugal Pump Handle Solids?** Purpose-built centrifugal sewage and slurry pumps use internal passages designed for solids-containing liquid. They are often useful where relatively high flow is required. However, abrasive material can gradually wear internal surfaces even when it passes without clogging. ### **When Does a Diaphragm Pump Make More Sense?** A diaphragm pump can make more sense for: **·** Sludge **·** Chemical slurry **·** Moderate solids **·** Shear-sensitive material **·** Fluids that should not pass through a high-speed rotating element AODD selection should still include maximum solids size and fluid compatibility. ## **Which Pump Handles Changing Pressure Better?** A positive displacement pump can maintain movement against changing resistance more directly than a centrifugal pump, but that behavior also creates a safety consideration. If the discharge becomes blocked, pressure can continue to rise. ### **Why Does a Positive Displacement Pump Need Pressure Protection?** A closed discharge path can expose the pump, hose or piping to excessive pressure. The system should therefore use appropriate pressure control or relief arrangements according to the pump and installation. A centrifugal pump behaves differently. Closing a discharge valve moves the operating point toward shutoff rather than trapping and forcing repeated fixed volumes in the same way. This distinction is important when planning system protection. ## **Which Pump Is Better for Chemical Transfer?** Chemical compatibility matters more than pump category alone. Both centrifugal and positive displacement pumps can handle chemicals if their wetted materials suit the fluid. For example: **·** Fluoroplastic-lined centrifugal pumps can suit corrosive continuous transfer. **·** AODD pumps can use different body and diaphragm materials for aggressive or viscous chemicals. The chemical name, concentration, temperature and solids content should be known before selecting materials. ## **Which Pump Is Better for Continuous High Flow?** Centrifugal pumps are generally the stronger starting point for continuous high-flow service with low-viscosity liquids. Their rotating design produces smooth flow without the repeated displacement cycles used by many positive displacement pumps. Applications can include: **·** Cooling-water circulation **·** Large water transfer **·** Irrigation **·** Municipal pumping **·**Process circulation If the main requirement is moving a large amount of water continuously, a centrifugal design is often easier to evaluate first. ## **Which Pump Is Better for Intermittent or Difficult Fluid Transfer?** Positive displacement pumps often become more attractive when the application is intermittent or the fluid creates special handling challenges. Examples include: **·** Drum transfer **·** Chemical unloading **·** Sludge movement **·** Paint transfer **·** Viscous liquid transfer **·** Fluids containing solids The absence of an electric motor at the pump is another reason AODD units are considered in some hazardous or temporary installations, although the overall site must still meet applicable safety requirements. ## **How Can You Choose Between the Two Pump Principles?** Start with the liquid and process rather than choosing a pump category first. Ask these questions: 1\. What liquid is being pumped? 2\. What is its viscosity? 3\. Does it contain solids? 4\. What flow is required? 5\. What pressure or head is required? 6\. Does flow need to remain relatively constant as pressure changes? 7\. Is continuous high-volume operation required? 8\. Is compressed air available? 9\. Are special materials needed? 10\. Does the fluid require gentle handling? The answers usually point more clearly toward one pumping principle. ## **Centrifugal or Positive Displacement: Which Is the Better Fit?** Choose a centrifugal pump when the application favors smooth, continuous flow of lower-viscosity liquid. Choose a positive displacement design when viscosity, solids or changing pressure make controlled displacement more useful. DEFUCC can be evaluated across both categories rather than as a single pump type. Its catalog includes centrifugal pump families for water and industrial service plus AODD pumps for chemical, wastewater, solids-containing and viscous-fluid transfer. [Get Free Quote](https://www.defucc.com/wp-content/uploads/wp-mfa-exports/page/contact.md)