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Fan amps and watts

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#1
vipejc

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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC at 25 C, but my case temperature varies from 45 C to 65 C. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?

Edited by vipejc, 14 December 2012 - 10:24 AM.

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#2
jaclaz

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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?


(8.96-8.88)/8.88=0.009 or less than 1%, well within common tolerances.

No issues whatever with voltage, if the motherboard provides 12 V (usually and more likely 12.2 or 12.3 V) this value will never be increased.
The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%)
Voltage levels and current absorption are not linear when it comes to electrical motors.

Loosely, you can:
  • Think at Volts as you would think at the inner area of a water pipe.
  • Think at Ampere as you would think at the pressure of the water flowing through it.
  • Think at Watts as the quantity (instantly or per unit of time) of water coming out of the open end of the pipe.

To get more water you increase the pressure (the diameter of the pipe remains the same), as well if instead of flowing free from an open end of the pipe you make it deliver water in a container that is in depression, more water will flow (actually the delta of pressure is increased as well)

An electrical motor will normally attempt when under heavy stress/load (and this is not the case of a fan unless you "brake" it or it gets clogged with dust or whatever) to compensate a lower level of voltage by absorbing more Amperes.

As well, there could be issues with the (very brief in time) increase of Amperes needed to spin up, but any hardware manufacturer would take this into account when rating the current a header designed to have an electric motor connected to it can provide.


I see that you were not satisfied by the replies received here :whistle: :
http://www.overclock...-amps-and-watts
where at least you provided the make of the fan, Delta.
Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.


jaclaz

#3
vipejc

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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?


(8.96-8.88)/8.88=0.009 or less than 1%, well within common tolerances.

No issues whatever with voltage, if the motherboard provides 12 V (usually and more likely 12.2 or 12.3 V) this value will never be increased.
The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%)
Voltage levels and current absorption are not linear when it comes to electrical motors.

Loosely, you can:
  • Think at Volts as you would think at the inner area of a water pipe.
  • Think at Ampere as you would think at the pressure of the water flowing through it.
  • Think at Watts as the quantity (instantly or per unit of time) of water coming out of the open end of the pipe.

To get more water you increase the pressure (the diameter of the pipe remains the same), as well if instead of flowing free from an open end of the pipe you make it deliver water in a container that is in depression, more water will flow (actually the delta of pressure is increased as well)

An electrical motor will normally attempt when under heavy stress/load (and this is not the case of a fan unless you "brake" it or it gets clogged with dust or whatever) to compensate a lower level of voltage by absorbing more Amperes.

As well, there could be issues with the (very brief in time) increase of Amperes needed to spin up, but any hardware manufacturer would take this into account when rating the current a header designed to have an electric motor connected to it can provide.


I see that you were not satisfied by the replies received here :whistle: :
http://www.overclock...-amps-and-watts
where at least you provided the make of the fan, Delta.
Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.


jaclaz


Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Edited by vipejc, 14 December 2012 - 11:17 AM.

There's no such thing as a dumb computer question. Each of us interprets info differently. - Me

#4
jaclaz

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Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Good :), and the reason why I asked for them is because those data you provided are NOT enough for me to give you an accurate suggestion, and they sound "queer" to me.
If you prefer I would like to read myself the specs, or if you prefer even better I don't trust you on the info you posted :w00t: . .

Mind you I am (was) trying to help you, it is only logical that if you cannot judge by yourself if that fan is suitable , you evidently miss some related electric/electronic knowledge :ph34r: , EXACTLY the same one that would allow you to decide what is necessary and what it is not.

And, as a standard, preventive disclaimer :w00t: :
http://www.msfn.org/...ost__p__1022573

jaclaz

#5
vipejc

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Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Good :), and the reason why I asked for them is because those data you provided are NOT enough for me to give you an accurate suggestion, and they sound "queer" to me.
If you prefer I would like to read myself the specs, or if you prefer even better I don't trust you on the info you posted :w00t: . .

Mind you I am (was) trying to help you, it is only logical that if you cannot judge by yourself if that fan is suitable , you evidently miss some related electric/electronic knowledge :ph34r: , EXACTLY the same one that would allow you to decide what is necessary and what it is not.

And, as a standard, preventive disclaimer :w00t: :
http://www.msfn.org/...ost__p__1022573

jaclaz


Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate. If you need something in specific, just ask and I'll share it.

Huh? The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%. Then 0.70A + 2.5% to 5% would put me over the cap.
There's no such thing as a dumb computer question. Each of us interprets info differently. - Me

#6
jaclaz

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Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate.

Never said that you were telling me lies, but maybe the actual specs may contain additional info that I would like to see and that you omitted as you rated them "unnecessary".

If you need something in specific, just ask and I'll share it.

What about the EXACT Delta fan model and motherboard make/model? :unsure:
You know. like ;):

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.


jaclaz

#7
vipejc

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Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate.

Never said that you were telling me lies, but maybe the actual specs may contain additional info that I would like to see and that you omitted as you rated them "unnecessary".

If you need something in specific, just ask and I'll share it.

What about the EXACT Delta fan model and motherboard make/model? :unsure:
You know. like ;):

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.


jaclaz


I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.
There's no such thing as a dumb computer question. Each of us interprets info differently. - Me

#8
jaclaz

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I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.

Where exactly did you get the data for the fan? :unsure:

Unless I am mistaken, the specs are here:
http://www.delta.com...p?pcid=1&ptid=1
http://www.delta.com...20x120x38mm.pdf

AFB1212HHE -C -R00 / -F00 12 6.0 to 12.8 0.51 6.12

or here (more likely):
http://www.delta-ame.../AFB1212HHE.pdf


jaclaz

Edited by jaclaz, 15 December 2012 - 03:50 AM.


#9
vipejc

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I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.

Where exactly did you get the data for the fan? :unsure:

Unless I am mistaken, the specs are here:
http://www.delta.com...p?pcid=1&ptid=1
http://www.delta.com...20x120x38mm.pdf

AFB1212HHE -C -R00 / -F00 12 6.0 to 12.8 0.51 6.12

or here (more likely):
http://www.delta-ame.../AFB1212HHE.pdf


jaclaz


I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.
There's no such thing as a dumb computer question. Each of us interprets info differently. - Me

#10
jaclaz

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I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.

Good, this one, then:
http://www.delta-ame...CF00(REV00).pdf

it says that the power consumption is 0.51 A and consequently (at 12 V) 6.12 W, with a MAX of 0.70A/8.40W.

You didn't post initially this info.

That fan will normally use 0.51 A with PEAKS of 0.70 A.

Your motherboard provides (your specs that I did NOT check) 0.74A or 8.88W and provides a 12 V level.

You are well within any limits and you can safely use that fan attached to that motherboard.

jaclaz

#11
vipejc

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I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.

Good, this one, then:
http://www.delta-ame...CF00(REV00).pdf

it says that the power consumption is 0.51 A and consequently (at 12 V) 6.12 W, with a MAX of 0.70A/8.40W.

You didn't post initially this info.

That fan will normally use 0.51 A with PEAKS of 0.70 A.

Your motherboard provides (your specs that I did NOT check) 0.74A or 8.88W and provides a 12 V level.

You are well within any limits and you can safely use that fan attached to that motherboard.

jaclaz


I knew all that. The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?
There's no such thing as a dumb computer question. Each of us interprets info differently. - Me

#12
jaclaz

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I knew all that.

But you failed to post these data. :whistle:


The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?

No, what you are basically missing, and I am trying - at this point desperately Posted Image - to try telling you is that if you connect a (say) 24 V device (or a 36 V or a 48 V or a 5 V or *whatever* voltage) to a 12 V outlet, the max voltage present at the outlet will remain 12 V, it is what "comes out" of the outlet and not the specs of the device attached to it.

The specific device (fan) can run continuously at 12.8 V but it is designed to be powered at 12V (i.e. it has a target of being operated at 12 V though it can accept as low as 6V and as much as 12.8V).

Power absorption is another matter, if you attach a device rated for a higher power absorption (but within the right Voltage specs) to a power outlet, the device will attempt to get more power (up to it's own specifications).

As a matter of fact when you connect a load to a voltage output, the voltage level might drop a little, but NEVER increase, if your motherboard ouputs 12V (as a matter of fact, if you had a mutimeter, you would measure on it - as said - most probably 12.2 or 12.3 V with no load connected to it and exactly 12 V or more likely 11.9 V with a "heavy" load connected) you will NEVER be able to get 12.8V from it.

Examples (simplified, and in order to let you understand) in case of BOTH an unprotected/unlimited power supply and of an unprotected/unlimited device:
Power supply specs:
12V 1A hence 12W
  • If you attach to it a device rated 6V 1A (6W) continuous, the device will burn in no time (because the voltage operating range of the device is greatly exceeded) .
  • If you attach to it a device rated 12V 1A (12W) continuous, both the device and power supply will work for years without issues (this device may well have peaks or "MAX" of up to 40% more than standard absorption - or even higher "transient" current spikes without any consequences to the device or to the power supply)
  • If you attach to it a device rated 6V 2A (12W) continuous the power supply OR the device will burn in no time.(because the voltage operating range of the device is greatly exceeded OR the current capabilities of the power supply are greatly exceeded)
  • If you attach to it a device rated 24V 1A (24W) continuous the power supply is very likely to burn (because the device will attempt to draw more current to compensate for the lower voltage)

Additionally voltage and current are linked together by Ohm's Law:
http://en.wikipedia.org/wiki/Ohm's_law
that is the same, written differently, that gives you V x A = W (when talking of DC, NOT AC)
http://www.csgnetwor...m/ohmslaw2.html
the MAX current that device will draw is 0.70A at 12V, if you supply it with a higher voltage, let's say 12.8V it will draw LESS current, i.e.
12 x 0.70 = 12.8 x X -> X=~0.66 A

If you attach to an outlet (BTW surely protected from overcurrents) rated for 12 V 0.74A that particular fan, it will run normally at 12V (and NOT at any higher voltage) absorbing normally 0.51A with the possibility of peaks up to 0.70A.

The outlet can provide UP TO 0.74A at 12V (8.88W), the device will nornally use 0.51A at 12V (6.12W) with peaks up to 0.70A at 12V (8.40W).

You are well within the specs.

jaclaz

#13
vipejc

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I knew all that.

But you failed to post these data. :whistle:


The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?

No, what you are basically missing, and I am trying - at this point desperately Posted Image - to try telling you is that if you connect a (say) 24 V device (or a 36 V or a 48 V or a 5 V or *whatever* voltage) to a 12 V outlet, the max voltage present at the outlet will remain 12 V, it is what "comes out" of the outlet and not the specs of the device attached to it.

The specific device (fan) can run continuously at 12.8 V but it is designed to be powered at 12V (i.e. it has a target of being operated at 12 V though it can accept as low as 6V and as much as 12.8V).

Power absorption is another matter, if you attach a device rated for a higher power absorption (but within the right Voltage specs) to a power outlet, the device will attempt to get more power (up to it's own specifications).

As a matter of fact when you connect a load to a voltage output, the voltage level might drop a little, but NEVER increase, if your motherboard ouputs 12V (as a matter of fact, if you had a mutimeter, you would measure on it - as said - most probably 12.2 or 12.3 V with no load connected to it and exactly 12 V or more likely 11.9 V with a "heavy" load connected) you will NEVER be able to get 12.8V from it.

Examples (simplified, and in order to let you understand) in case of BOTH an unprotected/unlimited power supply and of an unprotected/unlimited device:
Power supply specs:
12V 1A hence 12W
  • If you attach to it a device rated 6V 1A (6W) continuous, the device will burn in no time (because the voltage operating range of the device is greatly exceeded) .
  • If you attach to it a device rated 12V 1A (12W) continuous, both the device and power supply will work for years without issues (this device may well have peaks or "MAX" of up to 40% more than standard absorption - or even higher "transient" current spikes without any consequences to the device or to the power supply)
  • If you attach to it a device rated 6V 2A (12W) continuous the power supply OR the device will burn in no time.(because the voltage operating range of the device is greatly exceeded OR the current capabilities of the power supply are greatly exceeded)
  • If you attach to it a device rated 24V 1A (24W) continuous the power supply is very likely to burn (because the device will attempt to draw more current to compensate for the lower voltage)

Additionally voltage and current are linked together by Ohm's Law:
http://en.wikipedia.org/wiki/Ohm's_law
that is the same, written differently, that gives you V x A = W (when talking of DC, NOT AC)
http://www.csgnetwor...m/ohmslaw2.html
the MAX current that device will draw is 0.70A at 12V, if you supply it with a higher voltage, let's say 12.8V it will draw LESS current, i.e.
12 x 0.70 = 12.8 x X -> X=~0.66 A

If you attach to an outlet (BTW surely protected from overcurrents) rated for 12 V 0.74A that particular fan, it will run normally at 12V (and NOT at any higher voltage) absorbing normally 0.51A with the possibility of peaks up to 0.70A.

The outlet can provide UP TO 0.74A at 12V (8.88W), the device will nornally use 0.51A at 12V (6.12W) with peaks up to 0.70A at 12V (8.40W).

You are well within the specs.

jaclaz


Thank you for confirming the fan is OK for my system. I needed to be sure to avoid damage. Just one last thing, are all motherboard fan headers protected from overcurrent? Also, if you store a fan for years and then decide to use it someday, would the oil on the bearings be dried up and the fan useless, or would the fan work like the day you bought it because the fan and the oil were never worked?

Edited by vipejc, 16 December 2012 - 04:57 PM.

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#14
jaclaz

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Thank you for confirming the fan is OK for my system. I needed to be sure to avoid damage. Just one last thing, are all motherboard fan headers protected from overcurrent? Also, if you store a fan for years and then decide to use it someday, would the oil on the bearings be dried up and the fan useless, or would the fan work like the day you bought it because the fan and the oil were never worked?


We are getting at every post nearer to :w00t::
http://www.imdb.com/...es?qt=qt0247572

What one normally do would be:
  • connect the fan to a 12V DC power source (directly coming from the PSU
  • observe if it starts spinning
  • if NO goto 10
  • if Yes goto 5
  • let the motor warm a little, let's say by having it spin 15 minutes
  • connect it through a multimeter to the same power source
  • measure the amount of current it absorbs at start and when fully spinning
  • if current is within specs, goto END and mount it to the case
  • if current is above specs goto 10
  • remove (carefully) the label of the fan
  • remove the little retaining washer underneath
  • disassemble the fan from the motor
  • clean whatever residual of oil/grease is there
  • spray the bearing with some WD40 or similar
  • apply a tiny quantity of Superlube grease or similar
  • re-assemble the fan
  • goto 1

jaclaz

#15
Phaenius

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I would insert between 1 and 2:

1a. Take a safe distance.

#16
jaclaz

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I would insert between 1 and 2:

1a. Take a safe distance.

Sure :thumbup , low power computer case fans are known as the third main responsible of accidents on the job and sixth at home accordingly to a recent survey. :ph34r:
http://www.overclock...ad.php?t=484942

When testing these:
Spoiler

the standard advice is to get to Antarctica (and have a looong range remote to switch it on)


jaclaz

#17
Phaenius

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I don't trust anything with blades that spins at thousand RPMs.

#18
jaclaz

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I don't trust anything with blades that spins at thousand RPMs.

Sure :).
Lots of people from South Korea also fear those :ph34r:
http://en.wikipedia.org/wiki/Fan_death

http://konglishadven...ored-fan-death/

jaclaz

Edited by jaclaz, 17 December 2012 - 11:54 AM.


#19
Phaenius

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Well, yeah, but for different reasons. Keywords: blades, fast spinning, fingers.

#20
jaclaz

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Well, yeah, but for different reasons. Keywords: blades, fast spinning, fingers.

Add "less than 9 Watt" to the search keywords to limit the awful number :w00t: of verified accidents that you will find with your keywords :whistle: .

Also add right before your addition (that would become 1.b ):
1.a SECURE the fan with at least four bolts to the case and fix the case to the bench using straps, vises or similar before connecting, make sure that the bench is bolted securely to the floor AND to a wall, there are cases of small fans that took off taking the case and the bench with them.

jaclaz

Edited by jaclaz, 17 December 2012 - 01:40 PM.


#21
vipejc

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Thanks, Jaclaz. LOL When I read people are stupid enough to touch a moving fan, I laugh. Do not worry. I'm as careful as they come. Just read this entire thread.
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#22
Phaenius

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OK, jaclaz, next thing I when I will find you, I will bind you to a chair and move a spinning low power, inoffensive low watt fan around your eyes, nose and ears. Since this is harmless, you should have no fear.

#23
vipejc

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OK, jaclaz, next thing I when I will find you, I will bind you to a chair and move a spinning low power, inoffensive low watt fan around your eyes, nose and ears. Since this is harmless, you should have no fear.


When Jaclaz hits the fan. LOL
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#24
jaclaz

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Phaenius,
if you have a computer with a case fan or a PSU with a 120 mm fan, observe it accurately (with a torch since not only the PC is off but - for safety reasons - you have cut out electricity in your neighbourhood ).
That fan is mounted to EXTRACT air from the case.
The hypothetically finger cutting blades are on the INNER side.

A typical fan (like the one we were talking about) will have 7 (seven) blades.
Roughly 2/3 of the circular corona between the central motor and the outer of the fan is "blades" and 1/3 is "air".
At the very outer part of the fan, let's assume 110 mm you have a circumference of 110*Pi.
Your "target" when you will attempt to insert a finger in it is at the most 1/7*1/3*110*Pi=~16.45 mm wide.
The thickness of the fan is 38 mm (i.e. the actual hypothetically cutting edges of the blades are some 35 mm from the exterior).
But the blade is rotating by definition at 3.000 RPM, this means that it's speed at 110 mm outer diameter is 110*3000/60=5,500 mm/s
Your target is "covered" in 16.45/5,500=~0,00299 seconds, let's say 3/1000 of a second.
You finger has to travel linearly "inside" the target for 35 mm in 3/1000 of a second to reach the cutting edge of the blade, i.e. it has to travel at around 11,706 mm/s i.e. 11.7 m/s, i.e. roughly 42 km/h.
Presuming that your hand starts from still with the point of your finger at 10 cm from the fan, the tip of your finger will need to accelerate from 0 to 42 km/h in 10 cm.
Assuming that acceleration is linear, the 10 cm will be covered at an average speed of 5.85 m/s (or 21 km/h) and will thus take .10/5.85=0,017094 seconds, i.e. roughly 2/100.
So we have 11.7/0.02=585 m/s2 or 59.65 G.

I guess that if your finger (and hand and arm) can stand that kind of acceleration, it will survive the fan-through experience alright :yes:

jaclaz

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allen2

allen2

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Completly Off Topic: Also, Phaenius, i don't know how you handle paper as it can be a lot more dangerous than a spinning fan because of those cutting edges. I'm pretty sure everyone here know someone that got cut by a sheet of paper but almost nobody know some that got hurt with a fan.
I did a lot of stupid things with like stopping them barehand when spinning (you just need to press on the center). No computer fan except perhaps one modded with with razor blades could cut a finger.




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