Forward Curved VS Backward Curved Centrifugal Fan

Aug 18 , 2022

Not all centrifugal fans are the same, the difference being the rotation of the impeller. The two most common types are the forward curved centrifugal fan and the backward curved centrifugal fan. And different configurations determine different performance and applications, and here we explain how they work and what they are used for.


What is the forward curved centrifugal fan?


The forward curved centrifugal fan is also known as the forward blade centrifugal fan. The forward curved impeller is characterized by a relatively large number of shallow blades facing the direction of rotation.


How forward bladed centrifugal fans work?


The flow from the impeller is generated in the tangential direction for the forward centrifugal fan. The forward curve of the blades transfers kinetic energy to the air, requiring a scroll housing to convert the kinetic energy into static pressure.


For any given constant speed, the input power characteristic increases as the flow rate increases from zero to a maximum. Therefore, at higher flow rates, it is important to ensure that the load on the impeller does not exceed the rating of the drive motor.

forward curve centrifugal fan

forward curve centrifugal fan


What applications can the forward curve centrifugal fan be used for?


Centrifugal fans with forward curved blades typically deliver large volumes of air at low operating speeds and are compact, small, lightweight, and easy to install and use.


The forward curved blades centrifugal fan is widely used in applications requiring constant airflow or constant pressure delivery, including automatic control devices, forced ventilation for electronic equipment, indoor duct dust removal, exhaust air, heat removal, environmental protection, air purification, pollution control, household boilers, warm air heaters, radiant heat pipe heaters, refrigeration, heating fan coil assemblies, and more.



What is the backward curved centrifugal fan?


The backward curved centrifugal fan is also called the backward inclined centrifugal fan. Backward curved impellers generally have a lower number of longer blades, facing away from the direction of rotation. The blades curve backwards from the inner edge to the outer edge, relative to the direction of rotation, and may be of plate or aerofoil form.


What is the working principle of backward curved blade centrifugal fans?


With the unique backward curved centrifugal fan design, the radial flow of centrifugal fans with backward curved blades is generated as the impeller generates static pressure over the longer length of the blades.


Positive pressure is generated on the front side of the blade, pushing the air outward, and negative pressure is generated on the opposite side of the blade. This negative pressure draws the air into the space, so the front side of the next blade draws the air up and pushes it outward.


It can therefore be used with or without a scroll expansion housing, combining a fairly steep pressure characteristic in the normal operating range with a power characteristic that will not overload the drive motor at higher flow rates.

backward curved centrifugal fan

backward curved centrifugal fan


What are the applications of the backward curved centrifugal fan?


EC backward curved centrifugal fan is typically used in higher efficiency, higher pressure applications where overall system efficiency is a key factor or where a scroll housing is not required.


The backward inclined centrifugal fan is mainly used for purification benches, purification units, ventilation duct dust removal, purification air conditioning systems, environmental protection, pollution control, and other refrigeration equipment supporting work, including high-pressure condensing (premixed) boilers, extraction and ventilation systems, smoke exhaust systems, gas burner systems, heat recovery systems, etc.




Do you think a forward curved centrifugal fan will work well in your industrial facility, or is a backward curved centrifugal fan better? It's not always easy to make the right choice.


AMX is one of the leading forward curved and backward curved centrifugal fan manufacturers in China, and we can help you to choose the best centrifugal fan based on your needs! Please feel free to contact us at for more info!

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