Noisy small equipment fans

Worn old sleeve bearings and noisy fan blade design. Replace with a nicely designed ball bearing fan. Alluminium framed / ally bladed fans seem quietest in my experience.

Most consumer use fans try to move air by trading velocity (noise) for horsepower or torque. I hate the noise of fans, especially a loud bathroom fan or automobile AC fan. Totally unnecessary but cheepo!

Ivan Vegvary

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Sounds like a sleeve bearing fan and the bearings have gone dry. Quite often they can be rejuvenated by re-lubricating the bearing. I have a couple in my PCs and they require treatment every couple of years. Normally you can left the label off the centre and you'll find the end of the shaft with a small circlip, so far all the circlips have been plastic, so remove the circlip and the fan and shaft can be removed. Clean the shaft and bearing with some tissue , add a drop of oil, I use airline oil, and re-assemble and all should be well again. BTW one fan has a rubber bung sealing the end of the shaft which needs to be removed.

First, clean 'em. A bit of dust buildup can imbalance the fan blades. Then make sure there's no interferrence (like a nearby loop of wire). If it's still rattling, either the lube is gone (I like TriFlow for this application), or the bearings are loose (and a bit of size measurement, and reading of the power, volts and amps, followed by catalog searching and mailorder of the replacement part...).

To relube, you can either find the label and insert a hypodermic, or fully disassemble (but if you gothat far, it's best to have a new part available anyhow).

The whir and rushing air sounds are, of course, normal; turbulent flow is REQUIRED for best heatsinking.

If I'm going to bother taking them apart, I replace the fans with new ones of similar size and rating (but often higher quality), from Digikey, Newegg or whatever.

To some extent, if you have high airflow, you will get noise, but some real industrial fans whine like little jet engines when new, and are are unsuitable for an office or home environment.

The rattling is usually an indication the bearings are shot. I've not had much luck with oiling them, the fan quits again soon, and a bad fan can shorten the life of the device (it's often the initial cause of PC power supply failures, which leads to overheating, then a semiconductor gets smoked).

The sleeve vs. b.b. choice is not as clear-cut as it once seemed, from what I've seen. Quiet life of each may not be that different.

I agree. A little squealing can be lubricated away, but rattle usually is too far gone. If the blade rocks to the side more than a new fan of the same size, I replace it.

If that is a Rotron muffin fan (now Comair Rotron), they used to offer a lubrication kit which included a hypodermic to puncture the rubber seal and an oil with lots of toxic hazard warnings affixed to the container.

The old ones had the rubber seal under the label. Some newer ones have an aluminum washer staked into place over the rubber -- the hole in the center allowing the hypodermic access to the rubber without removing a label or having to guess where to poke in. :-)

BTW I got an interesting fan at the local metalworking club meeting last Tuesday. It is a 1" cube, powered by your choice of 26 V or 115 V -- but 400 Hz in either case. You adapt to 115 V 400 Hz by hooking a second capacitor in series with the whole thing. :-)

I haven't bothered to hook it up yet, but I expect an impressive amount of airflow through it (for its size) when I do.

Enjoy, DoN.

Rattling is usually bad, means the bearing is going or gone. Can also be something stuck in the works. Laptops present problems because fans are usually a custom component, sometimes integrated with a heatsink and/or heatpipe that feeds from the CPU. There are online laptop boneyards for some parts, you'd have to google the exact model. I've had some luck with sleeve-bearing fans taking them apart, cleaning the shafts and fan blades, then relubing and reassembling them. I don't use them again in critical locations. Standard size fans can be had for cheap off the internet, I usually buy them by the dozen. Noisy ones get replaced as and when needed. Watch the bearing types, noise and air movement ratings.

Stan

OK, thanks to all. I took apart the car inverter. The fan in it is "SP402012H", which means 40x40x20 12v fan. The fan blade inside seems to be very freely moving about where it is mounted.

There are many replacements on digikey, including quiet, ball bearing, etc. They all cost 11-12 bucks. Considering that I have a replacement inverter, this makes replacement kind of questionable economically. Since I took the thing apart anyway, I just might replace the fan for my education.

So far I like Digikey item P12820-ND the most, as it is only 20 dB (quiet), is ball bearing, costs $11.44 etc.

Item:

i

Is the existing fan nice and quiet after removal from the inverter, Ig?

--Winston

Only about 2 months ago, I was looking on eBay for some 40x10mm ball bearing fans and saw shitloads of 40x20 units.

The higher prices were about $6 each, and I selected 10 with an individual price of a under $3 each, with reasonable shipping. If the equipment I was buying them for didn't have size constraints, I would've bought the 40x20 units. I don't remember the name now, but the individual wrappers were marked with an equipment manufacturer's name and stock number (Cisco maybe), not just cheap bulk crap.

There are some eBay sellers that are very flexible on item prices for quantities when they use the -or- Make Offer feature. I'll generally ask about a quantity of items.. 10-50 (not 2 or 3) to make the total amount more appealing to the seller.

I like buying DigiKey products because I believe it turns over fairly quickly, not ever likely to receive any 5 year old capacitors they haven't sold out of yet, for example.. but I kinda doubt that the D-K fans are of extremely high reliability, but maybe they are. If they were described as Swiss or German manufacture, maybe.

WB, I have seen many ebay sellers selling counterfeit crap of this nature. I would not really care to save $5 or so and not be sure of what I am getting.

The digikey item has 50,000 hours rated life, ball bearings, and guaranteed 20 dB noise. That alone makes it worth the extra $5 to me. Plus I know that I will have it on Wednesday.

i

I know you'll do what's best.. and also know you're fullashit, because you've bought numerous auction items, and most/many times, you didn't know precisely what you would be getting.

Pick another argument, genius.

I don't own an inverter (but have repaired several for friends), and therefore don't know how long one would need 120VAC from a 12VDC? source, since I have DC/DC converters for my portable equipment.

IME, many of the mainland China sellers sell a lot of crap, and numerous domestic sellers that sell only junk products sell crap, but sellers that sell mostly quality stuff frequently have quality items and no crap.

But that's just my experience, and I've bought a lot of stuff, and much of it is parts and and miscellaneous components, however my buying decisions aren't primarily made on the price of the items.

Searching on eBay (or many places online) by specific product specifications isn't easy. DigiKey presents product specs, although it's not common from most retail sites (which D-K isn't).

It's likely that the original 40mm fan in the inverter was actually worth about 50 cents. If I only owned 1 piece of equipment that had a 40mm fan in it, I might consider buying 1 fan.. as it is, there are about 30 of 'em just in this room - in removable HDD trays, video surveillance DVRs, mobile DVRs, VCRs/AVTRs, soldering stations and various other equipment.

You said a lot of words, but all to no logical end.

The bottom line is that it makes no sense to try to save $3 and get who knows what, as opposed to spending $11.40 at Digikey and get a fan with guaranteed specs of 20 dB and 50,000 hours of life, and have it delivered on Wednesday.

i

A little update. I received the 20 dB replacement fan from Digikey. The cost was $11.46. I tried it on a power supply and it was as quiet as advertised. I installed it in the inverter and the difference was nothing short of dramatic. I have to make an effort to hear that fan, it is almost silent.

Note that the CFM rating matches the original. The difference is mostly cost, this fan probably cost $3 to produce and the original, I would guess, 50 cents.

With a 50k hours service life, even adjusted downwards for running in hot summers heat, this will clearly last me a very long time. Assuming

1 hour per day use of inverter, and being conservative about fan life, it would be 20,000 days, or 54 years. Then, at the age of 94, I might splurge for a new inverter. ;-)

We'll see how it really works out though.

i

Quick, order a spare fan so in 54 years you can save the cost of replacing the inverter. At 94 you'll never get your money's worth out of a new inverter!!!!

Well, if I invest 11.42 and realize 10% returns, after 54 years I would have $1,961.06, plenty enough to buy a few dozen spare fans. :)

i