Is there a way to measure airflow?

[Chiyawa]

Hi,

 

Recently, I bought some fan (unbranded) but I wanted to know if the fan can achieve the advertised CFM (or close to it). Is there a way or a device to make that measurement?

 

Regards,

Chiyawa

[MrMcMuffinJr]

2 minutes ago, Chiyawa said:

Hi,

 

Recently, I bought some fan (unbranded) but I wanted to know if the fan can achieve the advertised CFM (or close to it). Is there a way or a device to make that measurement?

 

Regards,

Chiyawa

It's called an Anemometer. should be pretty cheap on amazon

[Master Disaster]

Yeah, its basically a little windmill attached to a gauge.

[Stahlmann]

While you can buy a measuring device yourself you have no way of measuring the same way the manufacturer of the fan does. They often either have their own testing devices or let a testing facility do it. Either way you will likely have completely different results.

[Naijin]

28 minutes ago, Stahlmann said:

While you can buy a measuring device yourself you have no way of measuring the same way the manufacturer of the fan does. They often either have their own testing devices or let a testing facility do it. Either way you will likely have completely different results.

This is correct.

 

@ChiyawaWhat can do however, is compare the results of those unbranded fans with a different fan, screwed in the exact same position and same rpm. That would give a comparable difference.

[LogicalDrm]

As said, CFM measurements are not standardized. There's no way of knowing if measuring is done right next to fan or some length away. So testing something on your own is only good if you want to compare multiple fans.

[NorKris]

10 hours ago, MrMcMuffinJr said:

It's called an Anemometer. should be pretty cheap on amazon

I tried this once..  Fan->Radiator->Duct->Anemometer. I made it so no air could escape the Anemometer..

 

but the results didn't not match what i expected: highest CFM after rad = best temps 

[For Science!]

5 minutes ago, NorKris said:

I tried this once..  Fan->Radiator->Duct->Anemometer. I made it so no air could escape the Anemometer..

 

but the results didn't not match what i expected: highest CFM after rad = best temps 

what were you expecting?

[NorKris]

Just now, For Science! said:

what were you expecting?

that highest cfm gave me best temps.. but that was not the case 

[For Science!]

Just now, NorKris said:

that highest cfm gave me best temps.. but that was not the case 

you're trying to say that less airflow gave you better cooling? 

[NorKris]

Just now, For Science! said:

you're trying to say that less airflow gave you better cooling? 

Yes thats what happend. in my test i had:

Arctic P12

Corsair HD120

CM MF120r

CM Mirage fan

Vardar ARGB

 

HD won with Arctic and Vardar in second place..

with MF120 and Mirage last..

 

but in a temp test... Arctic and Mirage destroyed the rest

[For Science!]

7 minutes ago, NorKris said:

Yes thats what happend. in my test i had:

Arctic P12

Corsair HD120

CM MF120r

CM Mirage fan

Vardar ARGB

 

HD won with Arctic and Vardar in second place..

with MF120 and Mirage last..

 

but in a temp test... Arctic and Mirage destroyed the rest

You should write it up and post it as you may have discovered some new physics. But in reality its likely just poorly controlled experiments where the ambient temeprature has fluctuated.

[NorKris]

1 minute ago, For Science! said:

You should write it up and post it as you may have discovered some new physics. But in reality its likely just poorly controlled experiments where the ambient temeprature has fluctuated.

can prob do that. my temp testing was done by up to 4-5 run for every fan. Ambient temp was messured. i did avg of Max core, avg of lowest core.

 

That said, difference between the Arctic and HD was only 2-3C at 900 RPM(in p12's favor)... the only problem with that is... 1200 RPM on the HD is as loud as 1600 RPM on the Arctic.. 

[thrasher_565]

10 hours ago, NorKris said:

can prob do that. my temp testing was done by up to 4-5 run for every fan. Ambient temp was messured. i did avg of Max core, avg of lowest core.

 

That said, difference between the Arctic and HD was only 2-3C at 900 RPM(in p12's favor)... the only problem with that is... 1200 RPM on the HD is as loud as 1600 RPM on the Arctic.. 

were they tested with the same db or just speed? all fans have different rpms so go by db then get the performance that way but dont put mic in front of the fan so the air can hit it put it off to the side.

Edited March 27, 2021 by thrasher_565

[NorKris]

4 hours ago, thrasher_565 said:

were they tested with the same db or just speed? all fans have different rpms so go by db then get the performance that way but don't put mic in front of the fan so the air can hit it put it off to the side.

just speed. i dont have equipment to measure dp. and i live close to the metro/subway.. 

 

But in a way the db-factor is taken into account cuz i know that the loudfans like the HD and vardar has to beat the quiet fans with a good margin for them to really win. 

[Chiyawa]

On 3/26/2021 at 3:54 PM, MrMcMuffinJr said:

It's called an Anemometer. should be pretty cheap on amazon

On 3/26/2021 at 3:56 PM, Master Disaster said:

Yeah, its basically a little windmill attached to a gauge.

I see. Thanks for the info.

 

On 3/26/2021 at 4:39 PM, Stahlmann said:

While you can buy a measuring device yourself you have no way of measuring the same way the manufacturer of the fan does. They often either have their own testing devices or let a testing facility do it. Either way you will likely have completely different results.

On 3/26/2021 at 5:09 PM, Naijin said:

This is correct.

 

@ChiyawaWhat can do however, is compare the results of those unbranded fans with a different fan, screwed in the exact same position and same rpm. That would give a comparable difference.

True indeed. But I just want to see how much air the fan can push. This is a case fan, so I need a good CFM to cool GPU (RTX 2080 OC). The problem is that the existing case fan is too weak to push air into the case from the front, only having 30CFM (and yes, it was silent fan running at 900 rpm). I'm thinking of changing them to Cooler Master Sickle Flow fan, but my local store is out of stock.

 

On 3/27/2021 at 1:31 AM, LogicalDrm said:

As said, CFM measurements are not standardized. There's no way of knowing if measuring is done right next to fan or some length away. So testing something on your own is only good if you want to compare multiple fans.

I think they use a duct if not mistaken, The duct needs to have the correct diameter, though. Still, depending on the distance between sensor and fan, it could severely affect the reading.

On 3/27/2021 at 2:12 AM, NorKris said:

I tried this once..  Fan->Radiator->Duct->Anemometer. I made it so no air could escape the Anemometer..

 

but the results didn't not match what i expected: highest CFM after rad = best temps 

I see. But, uh, CFM fans are not design to push air through a radiator as far as I know. The fan design for radiator should focus on static pressure (mmH2O). Although nowadays, most fans are hybrid, meaning you can use it for case fans or radiator fans, as they have good CFM and static pressure.

 

[NorKris]

5 hours ago, Chiyawa said:

I see. Thanks for the info.

 

True indeed. But I just want to see how much air the fan can push. This is a case fan, so I need a good CFM to cool GPU (RTX 2080 OC). The problem is that the existing case fan is too weak to push air into the case from the front, only having 30CFM (and yes, it was silent fan running at 900 rpm). I'm thinking of changing them to Cooler Master Sickle Flow fan, but my local store is out of stock.

 

I think they use a duct if not mistaken, The duct needs to have the correct diameter, though. Still, depending on the distance between sensor and fan, it could severely affect the reading.

I see. But, uh, CFM fans are not design to push air through a radiator as far as I know. The fan design for radiator should focus on static pressure (mmH2O). Although nowadays, most fans are hybrid, meaning you can use it for case fans or radiator fans, as they have good CFM and static pressure.

 

cfm AFTER rads = the static pressure already did its job

[Chiyawa]

On 3/30/2021 at 3:13 PM, NorKris said:

cfm AFTER rads = the static pressure already did its job

Hmm... I haven't come across this type of measurement before. Okay, might worth a shot.