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,-- DaveCThis is an invalid return addressPlease reply in the news group

On Sat, 17 Mar 2007 10:11:18 -0700, DaveC Gave us: How about age of the bearings and crud on the fan blades?

Like this:I'll contact them and see if they're willing to disclose their supplier...Thanks,-- DaveCThis is an invalid return addressPlease reply in the news group

Cooling performance with 2 fans?

Mar 17, 2007 23 Replies

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DaveC 19 years ago

I'm the OP.

After reading the user manual closely, I found mention of a thermostatically controlled temp mains circuit. Mains power is cut if a sensor located near the critical element rises above a pre-set "safe" temperature.

So it looks like I can play in the "safety zone" of the fan's speed. I'm sure they built in a margin of safety, pushing much more air than is needed, on average. So I'm going to drop the speed of the built-in fan -- in trial steps

-- until the sensor trips. Then speed up the fan a little and see how it works, long-term.

Thanks, folks, for the suggestions.

DaveC me@bogusdomain.net This is an invalid return address Please reply in the news group

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Olin Perry Norton 19 years ago

A few years ago we bought some liquid/air heat exchangers from a company called Lytron. I recall that the fans that came with these heat exchangers (to blow air over the coils) were so quiet you could barely hear them running.

We used the Lytron 600o series heat exchangers.

See:

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I don't know who Lytron gets their fans from, but they are impressively quiet.

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DaveC 19 years ago

Like this:

I'll contact them and see if they're willing to disclose their supplier...

Thanks,

DaveC me@bogusdomain.net This is an invalid return address Please reply in the news group

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Olin Perry Norton 19 years ago

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They seem to use the Muffin XL, Patriot, and Caravel tubeaxial fans by Comair/Rotron.

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