Increasing collection fan RPM

Determining how much RPM that a fan can handle. March 19, 2001

Q.
I have a 2 HP 12" collector. I would like to increase the fan speed above what the motor turns. What RPM can the fan handle?

Forum Responses
Check with the fan manufacturer for maximum RPM. There was a shop here that had a fan lose a blade--made a mess out of a lot more than just the fan!

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Your 2 HP fan is probably a direct drive unit. Typically, direct drive fans operate at a fixed RPM, which is normally high (3450 - 3500 RPM). That is why they tend to be noisy vs a belt-drive fan, which generally operates at lower RPM. Example, 1,250 - 1,500 or so. A lot of belt drive fans might not be pulling full break horsepower and by changing the pulley arrangement, you can increase RPM and pull full break horsepower. Example, a belt drive fan in a dust system might be 10 horse power, but was originally set up to pull 8 break horse power, as at that level of power it will deliver the proper air flow required. By changing the pulley arrangement on such a fan, you could increase RPM to achieve full break horsepower and get a little more airflow.

Curt Corum, forum technical advisor