Question about Selecting Blade Type for an AHU/RTU 1

[David_HVAC_Learning]

So, I'm trying to learn what's done in the Mechanical Engineering HVAC Industry in regards to selecting a blade type for a fan. I've looked at Table 1 for Types of Fans in the ASHRAE HVAC Systems and Equipment Handbook and there it talks about the different blade types (airfoil, backward curved, etc.) for different fans. I'm mainly concerned with the centrifugal fan because I'm operating under the assumption that the centrifugal fan is the most prevalent fan used in the industry (aside from axial). So, when selecting from a vendor, am I typically able to select what blade type the centrifugal fan will have in the AHU/RTU, and if so, what is the go to blade type in a general building (office building, school, etc.)? And also, when is it appropriate to use one blade type versus another? Is there a situation where I would want to use Forward Curved Blades rather than Backward Curved Blades for a particular air handling unit? What do you guys do in your job? Any input on this would be appreciated. Thank you.

 

[HVAC-Novice]

FC=cheaper and less efficient. BC= more expensive, but more efficient. Airfoil even more efficient. But also depends on fan size and the actual application. Fan (and AHU) manufactures have selection software that ells you actual bhp for your conditions. Sometimes hidden they show actual kW. For some equipment they may not give you a choice in fans.
Most equipment I use doesn't offer Fc anymore.... it will just go away in most cases due to less efficiency. check out Fan Energy index (FEI)
Nowadays they also offer fan-walls (more than one fan with ECM).

Read the ASHRAE books and some other publications that go into general fan designs and applications.