Noise Reduction in Centrifugal Fan

This situation is scarcely credible.

Turn the fan off.

Baffles and ducting may change things. You may also have blowers that are mechanically failing. You may have to replace blowers with quieter units that move less air. You might have sheet metal that is resonating that needs to be damped. Without being there I cannot tell what is the source of the problem.

This is normal for centrifugal blowers. Redfred called it. You'll need to move the opening of the blower intake to some point above or away from people. That's where the sound will appear to originate.

Reducing fan speed will help, but this may not be practical.

Almost anything you do will reduce the efficiency of the blowers.

Or, ask the guys who build them.

These guys have been building blowers for years. Energy-efficient Industrial Blowers, Air-Jets, Air Knives & Drying ... Look on their website for help.

This company: Sonic Air Blowers - Sonic Air Systems was started by x-Paxton employees and their blowers are refined and they have a much better warranty than Paxton.

Dear Sir / Madam

1. Thanks for suggestion.

2. I will try to shift suction point little away from Blower and check the result.

Posts 2, 3, and 4 offer possible solutions. Need more info to truly find and reduce the problem.

Air velocity is a possible noise source. How fast is the air moving? 3600RPM fans can be very noisy in comparison to 1800 RPM fans. (presuming 60 Hz system).

Inlet to fan to small or poorly designed for smooth air flow is another possibility. Sharp duct turns at the inlet will create turbulance and cause unwanted noise.

Dear Mr Ried,

Thanks for your input.

Fan Flow Rate is 19000 Cub Mtr / Hr delivering pressure as 700 mmwc. It is directly coupled with Electric Motor of 75 KW X 2920 RPM. Electrical Frequency in India is 50 Hz. We have provided a suction pipe of 500 mm and 1 Mtr Long having wirenetting of 25mm size to stop entry of birds .

Regards,

( Aditya )

That size and type of fan is going to be noisy.

Inlet and discharge silencers will offer some capacity for sound reduction, you need to find specialist firms for this option.

Another option is to order larger, slower rotational speed fans and increase duct sizes to reduce air velocity.

Both options will require significant expenditures and knowledgeable design.

Dear Mr Ried,

Thanks.

Regrads,

( Aditya)