Shooting compressed air INWARD?

I just read someone suggesting the practice of shooting compressed air INWARD through the fan, to clean out a laptop fan--that is, putting the can right up to the vent, and blowing inward, to push the dust around, and presumably at that point, out.

This seems so counter-intuitive I did a double-take.

But what do you folks think of this? It sure would be a heck of a lot quicker and easier than halfway dismantling the laptop like I just did, and then having to take it to a computer shop, anyways...

 

Does seem weird. I have done this on a laptop that had vents in the back and on the side. I usually leave it running and just a little squirt or 2.

 

The problem with compressed air blown into fans, will cause the fans to exceed their safe RPM's. You do need to access the fan and stop the fan from turning while blowing the dust out.
Remember spinning up wheel bearings with compressed air (as kids will do) and watching while the bearings disintegrated.
The same thing may happen with comp cooling fans. Be careful out there. Cheers Neil.

 

Why would you try to blow dirt back into the laptop?

 

That is why I mentioned short blast. Not like kids would do just to hear it wind up.

 

The idea here is to clean out the dust, without having to disassemble the entire laptop.

I suppose this goes to teh heart of my concern, though--wouldn't dirt and dust just get blown back into the laptop?

 

OK, assuming that a toothpick could keep the fan from spinning while it got the blast (Not sure if the laptop would have to be disassembled to do this)....

 

When you blow air INTO the fan you are blowing against the fan's normal rotation which isn't a good idea for anything other than a short burst. Ideally, you'd want the long "straw" connected to your air can so that you can push it in beyond where it'll turn the fan against the rotation. You're also more likely to get nearer the dirt by pushing the straw in and consequently more likely to shift it but there's really no substitute for opening it out and cleaning it properly.

 

The guy at the computer store said that doing this would be ok.

I can accept that there's no substitute for the real thing, but doing so would cost 70 bucks or more next time, as I can't seem to complete the disassembling and would not attempt to do so to this model, at any point in the future, so this is really a matter of either doing nothing, or at least going through the vent.

 

I ruined a fan by blowing straight into it and my computer guru said that's a no no because you can force dirt to lodge deep inside of the bearings which can jam it up. Since replacing that fan, I will never again blow straight into a fan.

Now I make sure I vacuum it first with a straw taped to the vacuum tip, then sometimes blow across it very lightly or directly on the blades while keeping the blades from over spinning..

 

Actually, you can't force dirt into the bearings as they are sealed units. What you can do though is force dirt into the fins of the cooler and clog it up that way - which is what I think your comp guru meant.

 

You are right to be concerned about blowing dust in. But blocked vents are worse. So the idea is to blow (or wipe) as much dust as possible AWAY and not in. And the remainder all the way through the notebook, not just in.

Note this is best done frequently and regularly to prevent build-up, rather than only when it has built-up and notice or think heat is becoming a problem.

PCs are not a problem because you simply remove the side panel to gain access. But notebooks are a real PITA because they are proprietary, they don't allow easy access for the "normal" user. And what makes it worse, because notebooks are powerful computers jammed into a tiny box, they are prone to heat problems!

As far as compressed air and fans, it is not blasting dust into the bearings that is the problem. The bearings are sealed, packed in grease. If grease is not leaking out, dust will not get in - even with a lot of PSI.

The problem is, whether you use cans of compressed dusting gas (BTW - those cans do NOT contain "air" - they contain poisonous gases!!! - read and heed the label's warnings), or you use a properly equipped air compressor, if you don't hold the fans stationary (I use Popsicle/glue sticks - 100s for a couple bucks at any crafts store), the fans WILL spin faster than they were designed, or manufactured to spin. And like any motor that you "over-rev ", the bearings are subject to excessive stresses and undue wear-and-tear causing the motor either fly apart, or eventually seize.

With electric motors, you don't having flying pistons, but over-reving damages the bearings (or the channels they roll in) and if it does not immediately seize, the fan will be begin to rumble, slow down, send vibrations through the case, and bottom line; become ineffective at cooling.

So blast away, just try to minimize how much dust is blasted in. When you use a garbage disposal, you don't turn off the water as soon as the food is out of the disposal. You run the water until the food is pushed all the way out the other end, and into the main sewer. Same here. Keep blasting until the dust is pushed all the way out the other end.

 

I agree that heat is "a" main culprit. As noted in my sig, I understand it's power. But I am specifically talking about the excessive mechanical forces imposed on the components inside the device. They are forcing parts to physically rotate many more times the limits engineers ever expected. So they don't design and part for those forces. They are not designed to go that fast. Especially fans of lessor quality.

I pretty much think it is the same as pushing the peddle through the floorboard. You might go flying down the track, or the motor might fly apart. But even flying down the track puts a big toll on just about every part in that car. Even cars built for it.

From my experience, most computer makers (notebooks and PCs) don't use the quality fans I use in my builds. And with notebooks, you don't get to choose.

It is tempting, perhaps fun to see how fast you can make things spin, goose the dog, or toss someone's hair about. I just think it best to not to see how fast you can make your computer fans spin. They are pretty important devices. And it is so simple to stick a wooden stick or straw in there. And besides, a stationary fan makes it easier to aim, and direct the blast through.

Canned dusting gas may not hurt a quality fan, but a compressor sitting between 80 and 120 PSI definitely could. Motors don't have to burn up to fail. And the failure may not be immediate, but still fail prematurely because of the abuse.

Not all fans are equal. They come with all sorts of bearings, of all sorts of quality. There is a real science, not to mention aerodynamics of the blades and fan housing, to making a quality fan. Good fans are not cheap.

If a motor is not meant to go that fast, I just recommend not making it.

Yeah, if you invent something as part of your job, then it belongs to the company - or government in this case. I started out as an Air Force radio tech in the 70s, and still call myself an electronics technician first, and have been very familiar with brushless motors of all sizes and purposes since - but as "brushless motors ", not by his name. While your friend may not have received the name recognition of Faraday, Ohm, Volta, or others, his impact is just as great. I bet he has some neat stories to tell about the early days of electronics. I would like to pick his brain.

PS - I suspect TonyT does, but for anyone considering using an air compressor (by far, the best way to clean a computer IMO - outside of course) make sure it is the oiless type. Also, the process of compressing air heats the compressed air. When the air cools inside the tank again, moisture from it condenses on the interior tank walls, then runs to the bottom of the tank in a pool of nasty, rusty, dirty water you don't want splattered all over your electronics. So for electronics cleaning, make sure you use inline moisture and particulate filter, and open your petcock every so often.

 

lol :d

 

I blasted them with compressed air and got them spinning so fast, they lost their bearings and let it slip by! lol

 

I would not use an AIR COMPRESSOR to blow dust out of a computer period.
The fans ,will over rev their limit BUT!!!
Air that is coming from an air compressor CAN also remove surface-mount electronic
parts. Compressed air at 75psi and up can be very destructive.This type of air pressure
could defiantly drive dust into a sealed bearing.
Only use a device that produces air pressure close to the blower outlet on a vacuum
cleaner.

 

I am sorry but professional electronics facilities have been using compressed air for many years - typically set between 80 - 90PSI. Did you read this whole thread through before responding - like the part about Popsicle sticks?

I repaired USAF Control Tower radios at many bases and we always had compressed air - typically plumbed through the building. Every repair shop I have worked in uses compressed air. You have to for some of these devices that have never been cleaned. I have compressed air in my own shop and taking computers outside for blasting is a routine - daily occurrences.

Do you have to be careful? Of course. You have to be careful of flying debris in your eyes, and toxic bio-waste getting in your lungs. And you have to be careful you don't spin the fans faster than designed limits. It is simple to blow the dust away first, then move in close for finer work. That will NOT blow dust into the bearings - not unless the fan is failing anyway and the seals are leaking. If grease is not leaking out of the seals, dust will not get in.

It is totally incorrect that it will remove surface mount components. I have been blasting out TVs, stereo and home theater receivers, computers, UHF/VHF ATC radios - you name it - for at least 40 years and I have never knocked, seen, or heard of a component flying off. And again, that's at 90PSI or more (up to 120PSI).

If a device is blown right out of its solder joints, then it obviously was not properly soldered in the first place. Could something loose go flying? Sure. But that just means you did not prepare the computer for blasting first.

Air compressors do NOT produce hurricane force winds - even from a tiny opening of the duster nozzle. You don't jam the hose in there and let it fly loose banging into things either. It takes some care. But it, by far, the best method to clean out a computer - without dipping it in a sonic cleaner.

I mean, we need to be realistic here folks. If worried about 90PSI, don't put the nozzle up so close. And every compressor I have seen lets you toggle down the PSI to a lower pressure if you want - and that's fine, but it does not work as well.

Don't forget, bakeries use compressors to decorate cakes with air brushes. Face artists use it to air brush faces. Dentists blast compressed air in our mouths. Just remember to use a inline moisture and particulate filter.

Sorry, but the wide mouth of a vacuum nozzle does not create enough pressure. With a vacuum, you must also stick a soft brush in there to stir things up, then hopefully draw it into the vacuum.

And FTR, I discourage the use of vacuums, unless you are thoroughly familiar with ESD, and how to prevent it. Dust and air particles bang into the nozzle end as they zip by creating HUGE static potentials - far more than needed to totally destroy your CPU, motherboard, RAM and any other high-density devices.