100mm round fan 5V

smuggler.ie

Need round 5v 100mm fan , its not for PC, but intention to feed from USB power

Anywhere i look is either square or 12V.

Thanks

K.O.Kiki

The only company I know of that sells 5V fans is Noctua, and they only have square models in regular PC sizes (200, 140, 120, 92, 80, 60 & 40mm).

What's it for?

smuggler.ie

https://www.boards.ie/discussion/comment/121649329#Comment_121649329

Thanks.

it is for venting, but not PC (not directly anyway) . Some DIY project.

I want it to fit into 100mm duct. Currently have some old Intel CPU stock heatsink fan, but its 12V. Want it to run of USB.

Well, if its has to be square will have to make some sort of adapter to get to 100mm radius for duct.

Cuddlesworth

As the length of a duct increases, combined with larger diameter and bends/duct type etc, the CFM reduces significantly. And it has to draw air from somewhere within the property creating negative pressure to overcome. There is a big difference in the requirements of a PC fan and a usual duct fan.

So not sure if a 5v fan would do much of anything if it was attached to a duct of any real length.

Cuddlesworth

But something like that would do what you want right?

https://www.ebay.co.uk/itm/303912598068

smuggler.ie

this might work just right!

Disclosure:

i vape, for last 5-6 years since i quit cigarettes. And i "chain" in my office(s) (have two, one for work, one for after hours. Dont even know why now, should reconsider )

Rest of the family dont really need to inhale my bad habit but i am to lazy/busy to go out for a puff.

So....

As long PC/laptop run it need to be force extracted. With door closed (to reduce fumes escape)room heats up quite fast and natural vent cant cope in timely manner - sitting in the hot fog. Hence DIY

Duct is quite short as it goes through the wall right from the room(s) , 0.5m+

With PC dont have big issue - DIY extension from secondary CPU fan header, not elegant, but i dont care. Laptop is different story.

Perhaps could go with solar for 12V, but where do you get enough sun in this country, especially over late hours...

Thanks

Cuddlesworth

Right but the problem is that a PC fan, moves air from outside the case either into or out of the case. Its a small space with relatively unrestricted airflow and requires not much airflow.

With your door closed, a exhaust fan would be creating negative pressure trying to exhaust air without any real intake meaning it would be moving f all air really. Same reason the current vent doesn't do much, if the door is closed its going to move very small amounts of air passively.

If this is a upstairs room and its vaping/heat you want to get rid off, running a relatively quiet 240v bathroom extractor fan or inline fan separate to the intake vent would do a much better job. Preferably on the other side of the room.

smuggler.ie

https://www.boards.ie/discussion/comment/121660304#Comment_121660304

Good points, thanks.

Creating negative pressure seem good - air will be sucked in through gaps around door instead escape out, believe it puts some stress on the fan

Looking at numbers PC fans* wining so far, more research needed.

Currently as trial running this thing from old HP elite - HP p/n: 712960-001 (12V , 0.6A)

It does create good suction so far, ~1.9 m3/min according datasheet.

I did consider bathroom fan and even test run with one i have - way to much noise and 18W compare to current PC fan ~5W .

As for airflow, bath fan i tested is rated 70 m3/per hour - if not mistaking it is ~1.17 m3/min. Obviously there could be models that are more power/noise friendly.

If take nf-a9-5v as sample - compare to bath fan is similar airflow rate, but half of noise and only 1.3W.

Any thoughts

Cuddlesworth

I believe what you are looking for is Static pressure ratings, because you will get significant resistance as you pull air out of the room. Its the equivalent of putting a extraction fan on the rear of the pc and then duct taping pretty much all the other inlets/grills closed.

Cheap Bathroom fan - 12 mm H₂O

Noctua Fan - 2.28 mm H₂O

PC fans are not usually designed to extract air from rooms/houses but household extractor fans are. And yeah, the cheap ones are always loud.

smuggler.ie

https://www.boards.ie/discussion/comment/121671174#Comment_121671174

I see.

So if duct would be blocked, or in fact wind would blow into duct then PC fan would "choke" unable to overcome this under less resistance that bath fan would be capable to deal with.

Point. Need to look into it.

CPU fan still rolling and i have clean(er) air