RE: air pumps: which makes the least noise?

["Hess, Clay A" <clay.a.hess@boeing.com>]

>From my experience with air pumps, the best ones for least noise were the old 
>Silent Giants....unfortunately they are no longer manufactured.  But, the 
>concept is easy to duplicate if you wish to make your own silencer.....and 
>that is what I did with my Rena air pumps, as they were too noisy for my 
>liking.  Silent Giants were so quiet because they surrounded the vibrating 
>components in gravel about 1mm in diameter.  They also muffled the inlet tube 
>by coiling it through the gravel inside the canister that the vibrating parts 
>were in.  If money is no object or you cannot find gravel small enough, you 
>can buy #6 or #8 lead or steel shot that would work well in this application.  
>If you are worried primarily about noise, I recommend the lead, it is the best 
>sound dampening material for the cost.  However, if you worry about lead 
>toxicity issues, and I am not sure there would be any in this application, 
>then, steel shot would be your next best bet.  The steel shot may need to have 
>a slight amount of oil added to it to dampen the vibration between 
>BB's.....this is what Silent Giant did to dampen their gravel......it made the 
>gravel kind of sticky as the oil slowly evaporated and left behind a very thin 
>residue.  
The Silent Giant container held a volume of gravel about 3-4 times that of the 
vibrating components....so, 20% of the volume of your container should be the 
pump you are trying to quiet and then you should fill the other 80% of your 
container with shot or gravel.  I made my container out of scrap maple, a basic 
rectangular box with a removable top.  I screwed the top shut to eliminate any 
vibration that might come from that, and put a foam seal around the lip of the 
top as well.  This worked great for 10+ years until the pump finally gave out.
If anyone is interested in more details on how to build a sound dampening box 
for their air pump, I would be happy to draw pics before an upcoming meeting to 
share with you......just let me know.

Clay


-----Original Message-----
From: W Hung [mailto:wjhung2@yahoo.com] 
Sent: Tuesday, March 16, 2004 1:41 PM
To: gsas-member@thekrib.com
Subject: air pumps: which makes the least noise?


I'm looking at purchasing another air pump and want
one that's strong yet quiet.

Has anyone every owned the old supra series and the
newer tetratec deep water series. They look similar in
design. Which one is louder?

Also, if someone could compare noise levels of air
pumps that would be great. I currently own a Rena 50,
Rena 300, Tetratec AP50(loud) as well as the old
series Whisper 100. The quietest air pump I've ever
owned was a Penn Plax Silencer 50, but those are no
longer made. 

So here is my ranking for air pump noise. This is not
scientific: (the unacceptably loud level starts at the
Tetratec AP50)

Silent-------Good------Pretty Good-------Loud-----> 
PPlax Silencer
     Whisper 100
        Rena 50
                Rena 300
                                  Tetra AP50
                                          Challenger  

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