Just had a idea about locating ORINGs to seal isolated air passage.
I see one at hand every time I change my oil on my car.
Remove one off your old filter and see if it works!
Just a thought!
On 24 Jan 1997, rohre wrote:
> Almost an oxymoron, ie fans and noise are like ham and eggs, but fans and
> quiet are not.
> As the local fan guru on repairing computer fans, instrument, or recorder fans
> etc. I have learned some truths I eagerly share, as I could do better things
> that change out noisey fans, worn out fans, etc.
> Most manufacturing is a cost trade off. Given that, if a fan is used it is
> often a sleeve bearing fan. These are, or will, become noisey or wear out in
> two to five years. Customers become very unhappy with either result.
> Customers contribute to the problem by siting equipment in dusty locations
> where contamination of the fan bearing and lubricant accelerates the problem.
> For slightly more investment, you can buy a ball bearing fan, and I have never
> had to change those in computer disk drives, computers, instruments, recorders
> etc. where I have used them, and have ten years or more on some of those. Now
> I am referring to the so called "muffin" type of fans. Those from say 5
> inches square down to less than one inch square. Customer satisfaction with
> the main product is enhanced, callbacks to the manufacturer are fewer, and
> returns for noise are almost nil. Greater efficiency all around, productivity
> and long term cost savings.
> Noise reduction in use of Muffin fans, or small blowers: If you have any fan
> or blower that mounts by three to four screw holes, you can lessen acoustic
> coupling of the basic fan operational noise to the chassis acting as a
> sounding and amplification board. One trick from small blower motor days was
> to use rubber grommets so the screws pass thru a grommet that isolates the
> mounting flange from chassis metal contact. A flat washer under the screw
> head and the nut must be used, and the nut should be a locking nut, to
> complete this scheme.
> Now the mounting of a muffin fan always assumed the fan shroud would make hard
> contact with the chassis. This is not a minimum noise design. But at a small
> loss of air column coupling , you could use a large "O" ring to the face of
> the fan shroud, and rubber grommets on the screw mountings to isolate the
> Muffin type fans. If the thickness of the grommet is greater than the "O"
> ring, either compress the grommet, or substitute a smaller but flexible washer
> or even "O" ring, to acoustically decouple the screws from hard chassis
> contact. With the right size binding head screw or washer head screw, the
> parts count and labor of installation can be minimum for this. In all
> replacement work, I use the nuts with built in lockwasher to lessen the labor
> charge for "the washer dropped on the floor search time."
> Maybe other flexible mounting ideas that are low cost will come to mind. (RTV
> forming a gasket?) Just remember the hard mounting is like a piano sounding
> board, and anything you can do to prevent that should keep the fan quiet
> longer, no matter the style.
> 73, Stuart K5KVH
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