I've got a piece of lab test equipment that's about 30 years old. The cooling fan is very loud and I'm looking for ways to quiet it down.
I measure the fan's noise at 53dB (using A-weighted dB meter at 1m on-axis), although the fan mfr only rates it at 39dB. I attribute the discrepancy to "marketing reality distortion" or "wishful engineering".
The fan has no obstructions, front or rear, in the near airflow path. It does have an input screen, but removing this doesn't change the measured noise.
The design information I have found attributes the majority of self-generated noise of a free-standing fan to the air turbulence caused by the motor support struts.
The fan has these specs, according to the mfr's web site:
115v, 75Vmin; 60hz; 0.180a; 14.5w; 2650rpm; 90.0cfm; 0.22in h2o / 55.0Pa; 39dB.I've looked around for a fan pushing that much air and quickly realized that a quieter one probably can't be found. So I'm looking at other options.
From the information I can find I understand that using 2 fans in series increases static pressure; in parallel, increases CFM. If use 2 slower fans stacked together in series, will I be able to obtain the same cfm while running at less-than full speed? It looks like static pressure won't be a problem with 2 fans. (There is no way of adding fans in parallel without major enclosure hacking which is not an option.)
This is where I've been getting my info from:
Any suggestions would be greatly appreciated.
Thanks,