Need a small motor and fan to blow air into a 4 inch sphere

[David Parham]

I have a 4 inch sphere with a 22 mm opening. Inside this sphere I will have 3 styrofoam balls 20mm diameter each and 3 styrofoam balls about 5 mm each. I need a wind source to blow wind into the ball through a tube approximately the diameter of a drinking straw, the wind being strong enough to make the balls flail about randomly inside the plastic ball. I am having a hard time finding a small fan that will blow enough wind. I found a hair dryer/blow dryer which works OK but I want to use a fan that is easier to mount and use, rather than using a hair dryer. Any ideas on a good, small, high-velocity wind source? I hope I provided enough information, but please ask if you need more details. Thank you!

 

[fresh_42]

How about a CPU cooler?

 

[oz93666]

This is tricky ... You want fairly high pressure with very low flow ... a squirrel cage CPU cooler might just have enough pressure ,,, (the axial type wont)

... Worth a try ,very compact ...just $2 including delivery eBay will almost certainly work if you make the entry hole about 1cm dia

Aquarium pumps will be very quiet , will have the pressure , but you may need a big one, or many, to get enough flow , but you can put the pump/s meters away and feed the air in with tube ...

A car tire inflater will have just the right flow and plenty of pressure , but very noisy , not designed for constant use ... air can be fed in through long tube.

 

[Rive]

Some small, portable vacuum cleaners (you have to use the other side, of course) might exist in the required size/power.

Ps.: simplest answer is actually small size 'air blower'. They have just the right pressure and air delivery. You can check for noise level too.

 

[anorlunda]

I can't resist joking. A grad student with a straw.

 

[David Parham]

thx, All! just ordered a squirrel cage, need to convert the rectangular opening to round, should not be that difficult. but also, a question - will an aquarium water pump also pump simply air?

anorlunda - lol, that's the thing, that works perfectly, i tried it, and need something equivalent, but exactly the amount of pressure - was going to mention that but tough to articulate the exerted pressure used for that. funny, though bc that proves an amount of air flow that will work.

 

[jrmichler]

Add a Tee fitting to the straw as close as possible to the end that you blow into. Connect the Tee to a water manometer. Then you will know exactly what pressure you need. And centrifugal blower pressures are measured in inches of water, which is exactly what you get directly from a water manometer. No unit conversion needed. That pressure will be different for different size straws.

 

[anorlunda]

Add a Tee fitting to the straw as close as possible to the end that you blow into. Connect the Tee to a water manometer. Then you will know exactly what pressure you need. And centrifugal blower pressures are measured in inches of water, which is exactly what you get directly from a water manometer. No unit conversion needed. That pressure will be different for different size straws.

Bravo. That's very smart.

 

[DaveC426913]

will an aquarium water pump also pump simply air?

No.

 

[David Parham]

Add a Tee fitting to the straw as close as possible to the end that you blow into. Connect the Tee to a water manometer. Then you will know exactly what pressure you need. And centrifugal blower pressures are measured in inches of water, which is exactly what you get directly from a water manometer. No unit conversion needed. That pressure will be different for different size straws.

beyond my current scope of instrumentation, but great idea! will reply with results from Squirrel Cage fan, and Mattress pump. meanwhile the small, powerful 50mm cpu cooling fan worked only ok/shows promise, only after fitting a conical shape of semi-rigid card stock paper [ah, junk mail flyers come in handy after all!] for a smooth air flow vs the pcv round cap that had a hole drilled and reducing suddenly down to a straw size hold. That said, the 50mm fan is not quite strong enough to push through a faucet/water tap screen fitting inserted into the 22mm ball opening [designed to prevent the 5mm foam balls from falling out] and push the 3-20mm foam balls + 3-5mm balls all at once.

 

[David Parham]

to follow up, i got this, plenty of air, just what the doctor ordered/FYI: https://www.amazon.com/gp/product/B07G5KM1DM/?tag=pfamazon01-20

now, still need to use a variable speed controller for it: https://www.homedepot.com/p/Broan-Electronic-Variable-Speed-Fan-Control-in-White-57W/202905912

thx for all ur input, i continue to make progress!

 

[David Parham]

i hope someone answers my question here, otherwise i can ask in another thread: the 24-LED strobe light i bought does not adequately Freeze Frame the particles i use that blow around inside the 6-inch sphere, and even less so the particles moving around in the 4-inch sphere. would a stronger, more-LEDs strobe light tend to Freeze Frame things better? to me it seems that it would but i have bought so many products and have to do a lot of returns as i perfect my project. thanks in advance for input!

 

[Tom.G]

The poor freeze-frame performance is that the camera is collecting light for too long a time. Either the strobe stays on too long or there is another light source while the camera is active.

Either use a shorter strobe pulse, a faster effective camera shutter speed, or eliminate the other light source.

 

[David Parham]

thank you, that's my goal, looking for affordable strobe with x-fast strobe duration. no other light sources, as i try it in total darkness. i heard Xenon tends to be faster, but i found documentation indicating LEDs can accomplish the same. hard to find documentation about each product and its pulse strength and duration.