Choosing a Quiet 80mm Fan for UPS

[Stevoisboss]

I have a Tripplite SU1500RTXL2UA UPS that I got from my workplace. I want to use it next to a couple of computers I have at my desk. As expected, it is pretty loud. I used the software from Tripplite and found that it was idling at about 20C-30C. I opened up the ups after taking some safety precautions and found that it is a single 80mm 3 pin fan. So I want to replace it with something with good performance and ideally as quiet as possible. Any recommendations? 

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[Bombastinator]

Delta fan.  Just because it’s 80mm doesn’t mean it’s low cfm.  There are quiet 80mm fans but they may not blow enough air.  The loudness could be a dying fan bearing or it could be that it just needs a whale of a lot of air so it’s going to be loud.  Looking up the model number https://www.digikey.com/product-detail/en/delta-electronics/AFB0812SH-F00/603-1054-ND/1014385?utm_adgroup=Fans %26 Thermal Management&utm_source=google&utm_medium=cpc&utm_campaign=Dynamic Search&utm_term=&utm_content=Fans %26 Thermal Management&gclid=EAIaIQobChMIttr84Pzo6gIVZQnnCh0WSAdMEAAYASAAEgJ_SfD_BwE

 

it’s a ball bearing fan (so possible loud bearing) that puts out 46.5 cfm which is not low for an 80mm fan.  this low noise fan for example puts out only 25 cfm https://www.newegg.com/silenx-efx-08-12-case-fan/p/N82E16835226033

 

Part of the issue is many fans list cubic meters per second which is not the same scale

 

 

[mariushm]

Well, it's a Delta afb0812sh-r00 fan, which means you have access to the datasheet and therefore it's specs.

You can actually still buy the model here, where you also can get datasheet and specs : AFB0812SH-R00 Delta Electronics | Fans, Thermal Management | DigiKey

 

So it's a

80x80x25mm fan

46.6 CFM (1.30m³/min)  airflow ,

0.267 in H2O (66.5 Pa)  static pressure

4000rpm

4.08w

40dB noise

 

I feel the static pressure is more relevant than airflow, because the fan probably doesn't have a lot of air vents to suck air through or to push out air from the ups case, so an airflow optimized (ex. case fans) would probably not work well. You'll want to focus on pressure optimized fans, as in those fans that would be used with radiators on water cooling, to push air through the radiator fins.

 

You want to pick a fan that gets as close as possible to those parameters (airflow and pressure) , while having lower noise floor. 

You'll also want to pay attention to datasheet to the  static pressure vs voltage and/or  airflow vs voltage curves - your current fan has 46.6 CFM at 4000 rpm but your UPS most likely doesn't run it 100%, so for example you could potentially get a 6000 rpm fan with 60 CFM and have the UPS run it at 80% speed and be less noisy while getting same end result.

 

On Digikey, you could go and filter by dimensions and then sort by airflow or static pressure and then choose according to your budget and minimum performance levels

Here's a starting point, all 12v dc fans , that are 80mmx80mm (up to you to filter further and remove >25mm thick fans if those would not fit),sorted by price : https://www.digikey.com/short/zbvbr2

 

There's 340 of them.  Here's only 15, 20 and 25mm thick  fans (214): https://www.digikey.com/short/zbvbf8

 

You can sort these by static pressure or airflow and then get something close to the specs of your original fan.

 

For example, something that looks right to me would be these :

 

9GV0812P4J03 Sanyo Denki America Inc. | Fans, Thermal Management | DigiKey

Size / DimensionSquare - 80mm L x 80mm H 25.40mm

Air Flow 60.7 CFM (1.70m³/min)

Static Pressure 0.440 in H2O (109.6 Pa)

Noise46.0dB(A)

Power (Watts)5.6W

RPM 4500 RPM

Termination 4 Wire Leads

 

It's more noisy but that noise level is at 4500 rpm - if the ups adjusts speed, it will be more silent at lower rpm... it's expensive high quality fan

 

Something cheaper yet still very good

PF80251V1-1000U-F99 Sunon Fans | Fans, Thermal Management | DigiKey

 

44.7dB 4800 rpm , same story, will be more silent at lower rpm ... similar airflow and static pressure numbers, much higher than your fan  ... around 12$

 

Something much more silent yet close enough to your specs is this :

OD8025-12HBIP68 Orion Fans | Fans, Thermal Management | DigiKey

33dB , a bit less rpm, a bit less static pressure at 0.230 and 40 CFM which is close enough... more silent though.

 

There's also the lower rpm version of Sanyo Denki San Ace at 31dB ... a bit low on the static pressure but I'd be comfortable using it : 9S0812H4011 Sanyo Denki America Inc. | Fans, Thermal Management | DigiKey

 

These don't come with connector, but you can cut the connector from the old fan and solder or connect the wires to the new fan ...  the colors are standardized or they're easy to figure out ... you have your voltage (12v) , ground (-) and then rpm sensor (optional) and optional pwm input (4th wire) ... again, can just be not connected to anything.

 

 

Last but not least ... keep in mind that when in regular use, the ups will be cool , so it's normal to be 20-30 degrees.

However, the ups will get HOT when it actually does the work, converting 12v from batteries to 110v/230v ... when ac power fails ... so then the fan has to move air and cool the insides.

Also ,same circuitry will produce some heat after that power failure is over topping up the batteries... a process which can take a few hours.

So these are two reasons why you can't just go and buy a low rpm very "silent" fan from newegg and ignore those specs at the rated rpm and all that... when the circuit actually works an undersized fan may "cook" the circuit and reduce its life. In extreme cases, a fan failure may actually cause transformers inside to overheat and trip temperature fuses or other protections. 

 

Probably don't need same values or higher, probably within 10-20% of those specs will be fine. The manufacturer will often reuse a fan for multiple models to get cheaper cost by buying in volume, or maybe they went with that fan for reliability reasons (it's rated 70k hours) and not necessarily for those high specs (though they don't hurt). Just saying you can't just pick a "silent" fan from newegg or amazon and just plant it there, it don't work like that, if you care about the ups and making sure it will still work after a few power failures.

 

[Bombastinator]

Now there are 120mm quiet fans that meet those specs.  The problem is they won’t even near fit the 80mm hole.  If there is room and capacity to cut a much larger hole something might be done. What you’ve sort of got is an 80mm fan that acts a bit like a 120mm case fan through sheer rpm and attitude.  Cost is noise.  If there’s no space for a bigger fan I got no good answers for you.  I suppose it might be possible to build a box onto the end of the thing to hold the larger fan.  It’s going to need even more static pressure though. Maybe some high static pressure 120 made for extra thick radiators or something. Box would be ugly though and make the whole thing bigger.  Also still might not work right. 

[Stevoisboss]

1 hour ago, mariushm said:

Well, it's a Delta afb0812sh-r00 fan, which means you have access to the datasheet and therefore it's specs.

You can actually still buy the model here, where you also can get datasheet and specs : AFB0812SH-R00 Delta Electronics | Fans, Thermal Management | DigiKey

 

So it's a

80x80x25mm fan

46.6 CFM (1.30m³/min)  airflow ,

0.267 in H2O (66.5 Pa)  static pressure

4000rpm

4.08w

40dB noise

 

I feel the static pressure is more relevant than airflow, because the fan probably doesn't have a lot of air vents to suck air through or to push out air from the ups case, so an airflow optimized (ex. case fans) would probably not work well. You'll want to focus on pressure optimized fans, as in those fans that would be used with radiators on water cooling, to push air through the radiator fins.

 

You want to pick a fan that gets as close as possible to those parameters (airflow and pressure) , while having lower noise floor. 

You'll also want to pay attention to datasheet to the  static pressure vs voltage and/or  airflow vs voltage curves - your current fan has 46.6 CFM at 4000 rpm but your UPS most likely doesn't run it 100%, so for example you could potentially get a 6000 rpm fan with 60 CFM and have the UPS run it at 80% speed and be less noisy while getting same end result.

 

On Digikey, you could go and filter by dimensions and then sort by airflow or static pressure and then choose according to your budget and minimum performance levels

Here's a starting point, all 12v dc fans , that are 80mmx80mm (up to you to filter further and remove >25mm thick fans if those would not fit),sorted by price : https://www.digikey.com/short/zbvbr2

 

There's 340 of them.  Here's only 15, 20 and 25mm thick  fans (214): https://www.digikey.com/short/zbvbf8

 

You can sort these by static pressure or airflow and then get something close to the specs of your original fan.

 

For example, something that looks right to me would be these :

 

9GV0812P4J03 Sanyo Denki America Inc. | Fans, Thermal Management | DigiKey

Size / DimensionSquare - 80mm L x 80mm H 25.40mm

Air Flow 60.7 CFM (1.70m³/min)

Static Pressure 0.440 in H2O (109.6 Pa)

Noise46.0dB(A)

Power (Watts)5.6W

RPM 4500 RPM

Termination 4 Wire Leads

 

It's more noisy but that noise level is at 4500 rpm - if the ups adjusts speed, it will be more silent at lower rpm... it's expensive high quality fan

 

Something cheaper yet still very good

PF80251V1-1000U-F99 Sunon Fans | Fans, Thermal Management | DigiKey

 

44.7dB 4800 rpm , same story, will be more silent at lower rpm ... similar airflow and static pressure numbers, much higher than your fan  ... around 12$

 

Something much more silent yet close enough to your specs is this :

OD8025-12HBIP68 Orion Fans | Fans, Thermal Management | DigiKey

33dB , a bit less rpm, a bit less static pressure at 0.230 and 40 CFM which is close enough... more silent though.

 

There's also the lower rpm version of Sanyo Denki San Ace at 31dB ... a bit low on the static pressure but I'd be comfortable using it : 9S0812H4011 Sanyo Denki America Inc. | Fans, Thermal Management | DigiKey

 

These don't come with connector, but you can cut the connector from the old fan and solder or connect the wires to the new fan ...  the colors are standardized or they're easy to figure out ... you have your voltage (12v) , ground (-) and then rpm sensor (optional) and optional pwm input (4th wire) ... again, can just be not connected to anything.

 

 

Last but not least ... keep in mind that when in regular use, the ups will be cool , so it's normal to be 20-30 degrees.

However, the ups will get HOT when it actually does the work, converting 12v from batteries to 110v/230v ... when ac power fails ... so then the fan has to move air and cool the insides.

Also ,same circuitry will produce some heat after that power failure is over topping up the batteries... a process which can take a few hours.

So these are two reasons why you can't just go and buy a low rpm very "silent" fan from newegg and ignore those specs at the rated rpm and all that... when the circuit actually works an undersized fan may "cook" the circuit and reduce its life. In extreme cases, a fan failure may actually cause transformers inside to overheat and trip temperature fuses or other protections. 

 

Probably don't need same values or higher, probably within 10-20% of those specs will be fine. The manufacturer will often reuse a fan for multiple models to get cheaper cost by buying in volume, or maybe they went with that fan for reliability reasons (it's rated 70k hours) and not necessarily for those high specs (though they don't hurt). Just saying you can't just pick a "silent" fan from newegg or amazon and just plant it there, it don't work like that, if you care about the ups and making sure it will still work after a few power failures.

 

Thank you for such an informative reply. I ordered the 9GV0812P4J03 Sanyo Denki that you recommended. Hopefully it will be a bit quieter. I know the fan that I have now is well over 4 years old.