Replacing switch fans

[ITGURU]

I've got a POE switch i want to replace the fans on to make it quieter.

Has anyone done this before and can suggest where to get the fans from?

 

it currently has 2 x SUNON EF40201BX-0000-G99 12v 0.74w fans - i cannot find much online relating to the full part number.

 

Can anyone suggest to get some super quiet fans from to replace them with? they are 20x20x40mm

 

the fans don't appear to be cooling the power supply or anything so don't think fan speed etc is critical, although the switch has a fan status and low and high speed depending on load.

 

Image below of current fans.

 

thanks

[mrwoberts]

I think you meant, 40x40mm x20mm deep. (At least according to the Sunon specs... http://www.sunon.com/tw/products/pdf/DCFAN/EF4020_U.pdf)

 

If so, then a quick ebay search turns up lots of results for '40mm fan', just that most of them originate from HK/China; may take a couple of weeks to arrive.

[mrwoberts]

I think you meant, 40x40mm x20mm deep. (At least according to the Sunon specs... http://www.sunon.com/tw/products/pdf/DCFAN/EF4020_U.pdf)

 

If so, then a quick ebay search turns up lots of results for '40mm fan', just that most of them originate from HK/China; may take a couple of weeks to arrive.

Equally, searching for 40mm fan on Amazon yields much fruit. I particularly like, Noctua, Fractal and Gelid

[ITGURU]

I think you meant, 40x40mm x20mm deep. (At least according to the Sunon specs... http://www.sunon.com/tw/products/pdf/DCFAN/EF4020_U.pdf)

 

If so, then a quick ebay search turns up lots of results for '40mm fan', just that most of them originate from HK/China; may take a couple of weeks to arrive.

Equally, searching for 40mm fan on Amazon yields much fruit. I particularly like, Noctua, Fractal and Gelid

 

Yep sorry, typo error! Does i matter on their spec's relating to air flow and rpm though, if they have a 2 step speed?

[mrwoberts]

Does i matter on their spec's relating to air flow and rpm though, if they have a 2 step speed?

Air flow & rpm certainly matter, but it depends on the need. For example, some of the more 'silent' fans have an airflow around 3 CFM, whereas that Sunon seems to have a higher airflow rate of 10, and therefore has a higher RPM (around 6K), and would obviously make a lot more noise. But does it really need to be that high?? How hot does it get in and around that unit? Although, saying that, if it doesn't get that hot, that may be because of these fans...

 

Leaving the noise aside, since that isn't so important in a comms cabinet, you'd want to look for a high CFM & RPM.

I believe the connector is a 3-pin, judging by the photo, which usually means that it is able to be monitored, and can therefore ramp the speed up/down, depending on the demand. If you were concerned that the switch won't work that way, I'd aim to get a direct replacement; or just take a punt and buy a couple of good ones, for less than a tenner. If it doesn't work, you've only spent £ 10 on two fans.

[ITGURU]

Air flow & rpm certainly matter, but it depends on the need. For example, some of the more 'silent' fans have an airflow around 3 CFM, whereas that Sunon seems to have a higher airflow rate of 10, and therefore has a higher RPM (around 6K), and would obviously make a lot more noise. But does it really need to be that high?? How hot does it get in and around that unit? Although, saying that, if it doesn't get that hot, that may be because of these fans...

 

Leaving the noise aside, since that isn't so important in a comms cabinet, you'd want to look for a high CFM & RPM.

I believe the connector is a 3-pin, judging by the photo, which usually means that it is able to be monitored, and can therefore ramp the speed up/down, depending on the demand. If you were concerned that the switch won't work that way, I'd aim to get a direct replacement; or just take a punt and buy a couple of good ones, for less than a tenner. If it doesn't work, you've only spent £ 10 on two fans.

 

The switch is in open space so not confined. The fans spin high at first bootup but have always then run at their lower speed so doesnt appear to be overworked. judging by the spec sheet they are max 6800 the original fans, the switch UI doesnt state the fan speed but other models usually report a speed of 3500 approx.

[difinity]

I've replaced quite a few 4cm fans in a load of switches I repaired.

The fans are exhausting the heat from the ICs with heatsinks on which get a lot warmer than the power supply. It's the air flow that's the important part although fan speed does influence this. Depending on the load and switch placement you can get away with quieter fans that don't push so much air or is the noise a worn bearing ? You might be able to lubricate them if this is the case.

Avoid sleeve bearings as they get noisy quickly, there's also the traditions ball bearings and also maglev which are zero friction and quieter.

I'd stick with Sunon personally.

[limawhiskey]

Looks like there's space for a couple more so my suggestion would be add two more and re-wire their pins to have each pair wired in series to each header, thereby halving voltage and reducing spin speed.

 

Might be a good idea to test the circuit at various voltages first, that way you know the fans will still spin.

 

I have no idea about air flow theory with fans but assuming it's a a linear relationship that ought to maintain the total air flow.

Edited April 21, 2017 by limawhiskey