Big Blowers - What is the whining sound - bearings or air?

[WBear2GCR]

JJ, I would go for the rebuild... but it should be pretty easy to check the blower assembly itself for noise... fire it up and listen to see where the sound is radiating from. Is it the final amplifier assembly or back at the box??

if it is coming down the hose and out, then you can install what would be an acoustical LPF in the line... which is essentially a muffler...

Of course if it is the bearings, it should scream back at the blower itself. A stethoscope would be one way to listen to the bearings, but another is a wood stick placed on the bearing point and the end in your ear... if that's blazing loud then it's ur bearings...

if I had the problem and the time, I'd take the blower apart, and get at the bearing housing, and try to shoot some liquid lube in there and see if it quiets... if it did, then the rebuild is mandatory, not to mention taking the impeller off and running the motor without a load at different speeds and having a listen... the noise would be worse with the load of course. If ur bold you can fake a load while it runs...

the grind on spool down shows bad bearings anyhow...

so it's one of three possibilites:
- cavity resonance (organ pipe)
- impeller noise (related to "tip speed" - like a whistle)
- bearing noise

            _-_-bear

[KM1H]

If the blower still takes time to wind down there is a good chance there is no damage and a few drops of 0W-5 synthetic does wonders for long term silence.

[K1JJ]

Bear, yes, a stethoscope or listening stick is a good idea.  I will give it a listen.


Carl, I did try to oil it one time but it appears difficult to get at the bearings and requires special tools.  I may look it over again before bringing it in for a rebuild.

In its present state I can hear it all the way across the house when running - all bearing whine.  It's a really FB blower, otherwise.

T

[ke7trp]

Thats how mine was.  High pitched whine.  IT will be silent after rebuild.  Most of the time as hams, We get ahold of blowers second hand and they have alot more time on them then we think.  RF generators, BC rigs ect, are somtimes on 24/7 365 so wear is heavy. 

C

[W3RSW]

So with water cooled you still have to cool the water unless you leave the tap running. 

Need Flow meter as well as temperature shutdown control.  Water taken outside with pumps, radiators, more fans. ?  Water is not compressable so R.V. Required too.

Water treatment for magnesium and calcium precipitates?  - additives monitoring?

All is not simple in water world.

[WBear2GCR]

Liquid cool, closed loop with inert heat transfer liquid, then to a heat exchanger.

What was it they put the Cray computer in a bath of? Fluorinert? Or??

                 _-_-bear

[KM1H]

All is not simple in water world.

Pure distilled water and leakage current monitoring is all that is needed besides tubing, pump and a large enough container. After all this is not a 24/7 system. Making it smaller requires a transmission cooler (aka heat exchanger in that other world) and muffin fan. Temperature/flow monitoring are optional depending how close to the edge you want to live.

After XX hours the water will become sufficiently contaminated by metal ions to require changing. In the ham world that could be several years. Belmont Springs has 5 gal jugs for $6.49. You can ask about double distilling and deionization (aka 3D) if pushing the HV envelope.

[W3RSW]

Hmmm, we're getting close to a more fun project... Tubing, fans, large enough container....?
Need a little corn squeezin's added to that "de-ionized" water.
Your "xx" hours would magically be transformed to "xxx" Fine with three passes. 

Now a simpler fire water world.

[N5RLR]

Hmmm, we're getting close to a more fun project... Tubing, fans, large enough container....?
Need a little corn squeezin's added to that "de-ionized" water.
Your "xx" hours would magically be transformed to "xxx" Fine with three passes. 

Now a simpler fire water world.

Love it.  Works for me. 

* * * * * * * * * *

Seriously, I've followed this discussion with interest.  Many good points made that I'll be filing away in memory.  Bravo Zulu, gentlemen.

[W2VW]

Don't forget the shop vac.