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Comparing diaphragm pumps with centrifugal pumps Sep 17 , 2023

There are many different types of pumps on the market. Not sure whether to choose a centrifugal pump or diaphragm pump? What to consider before selecting a pump?


Both diaphragm pumps and centrifugal pumps transfer fluids from inlet to outlet valves at controlled degrees of pressure and quantities. What makes these pumps differ is the method in which the fluid is transferred as well as the viscosity of the fluid that can be moved and the required suction lift. These variables need to be taken into consideration before selecting a pump. What differences of Centrifugal pump and diaphragm pumps?


1. Working Mechanisms

Centrifugal pump use impellers that draw the fluid in at increased velocity, which assists in moving the fluid from the inlet to the outlet valve. Diaphragm pumps, on the other hand, use a flexible diaphragm that moves back and forth to create a pressure differential that moves fluid through the pump. When the diaphragm moves in one direction, it creates a vacuum that draws fluid into the pump chamber, and when it moves in the opposite direction, it compresses the fluid and forces it out of the pump.


2.Types of Fluids that are Transferred

Each pump works more efficiently with different types of fluids. Diaphragm pump can handle high-viscous fluids, which will not affect the flow rates. The thicker the fluid gets, the more the flow rate increases. Centrifugal pumps are ideal for lower-viscosity fluids as higher-viscosity fluids can result in frictional losses. The impellers of centrifugal pumps can present a risk to shear-sensitive fluids.



Regardless of the distance or the varying pressures at which the fluid needs to be pumped, diaphragm pumps will deliver consistent flow rates. The flow rate of centrifugal pumps varies according to pressure. Centrifugal pumps need to be constantly primed in the liquid that needs to be pumped, whereas diaphragm pumps can handle intermittent dry runs due to their self-priming capabilities.


Below are 3 main advantages of Pneumatic diaphragm pumps compared to a centrifugal pump:


1. Excellent head and self-priming capacity


A diaphragm pump can be operated without the need to fill the suction pipe (unlike the centrifugal pump), thanks to the fact that it is able to suck up the air contained in the suction pipe during the start-up phase, and eliminate such air through the delivery line (self-priming capacity).


2. Good dry running capacity


Thanks to the airtight separation between the pumping chamber and oil-bath lubricated transmission components, diaphragm pumps can withstand reasonable periods of dry running (e.g. when operating in self-priming mode or in the event of a break in the suction line) without negative consequences, such as overheating and seizing up of connecting rods and pistons, which occur on centrifugal pumps that cannot work dry.


3. Resistance to abrasion and corrosion


Because there are no mechanical parts in direct contact with the liquid , the diaphragm pump can pump liquids with acids, solvents, abrasive particles, sediments or slurry (corrosion resistance).


Contact with Cindy (sales9@defupump.com), we are air driven diaphragm pump Manufacturers have combined our knowledge and expertise in the pumping industry for you to better understand which one is best suited for you.

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