Quiet compressors

[strantor]

Five separate 60 db sound sources would be 67 db additive. There are online calculators. Still less than the smaller IR and Quincy belt drives which seem to be about 75-80 db.

Good point. I had wondered to what extent multiple noise sources would be additive. I thought about it for a few seconds and decided that since 5 people clapping isn't 5 times louder than 1 person clapping, that it must just "seem" a little bit louder since there is less dead time between claps. But as you point out, it actually is a bit louder, but not very much so.

I found one such online calculator, and while it has only room for 4 noise sources, I played around with it enough to reasonably estimate that (5) 51db noise sources (the 3rd compressor I linked to, if specs are to be believed) would be about 58db, about the level of a conversation.

 

[duanew1]

I used to have a Kobalt 26 gal oil free compressor. I always hated how loud that thing was. It scared me so bad the first time it turned on. It broke and I was tired of fixing it.

I love the belt driven compressors, but they are much more expensive. I picked one of these:

29 gal. 2 HP 15 PSI Cast Iron Vertical Air Compressor

It has been great so far. Time will tell how good it is. It is much quieter than my old compressor and more powerful.

 

[California]

What I'm thinking is ... I could buy 5 of them, plumb them together along with my 26 gal craftsman acting as a storage tank, and I'd have: ...

15.5CFM @ 90PSI
125 PSI max
51db (whisper quiet)

... connect an analog pressure sensor to a little programmable control board and when the pressure drops below, say 120PSI, it could switch on a single compressor, whoever has the lowest hours. And if it drops below 115PSI, it can switch on a 2nd compressor ...

Just for fun I set up a cheapskate solution similar to that: two 20 gallon air tanks from old Craftsman portable compressors, installed in a loft over a barn stall adjacent to my shop so if they blow up I'm out of range of the shrapnel. Then my HF 10 gallon / 2 hp (claimed) compressor plumbed to use those tanks as reserve. Its control and relief valve allow 120 psi, less than whatever those old Craftsman tanks were rated originally. The tanks came from a used-tool store in exchange for some mismatched and un-needed hand tools I inherited, so in effect cost almost nothing.

But after setting this up I've never used the extra capacity. I found that the red Earthquake impact wrench uses a lot less air than the HF cheap impacts I had prior, which had sent me looking for a solution. HF's $9 HVLP spray gun doesn't need more air than what I had before. I don't have an application that needs more air output than these two tools. Its no problem if inflating a tractor tire etc takes a while.

One problem I see with the multiple compressor scheme: maintaining it. After a few years I had to replace the controller on my HF compressor. The electrical contacts were corroded. No big deal, $15 for a new generic controller off Ebay. But I wouldn't want to multiply this maintenance x 5.

And related: HF's compressors on wheels use a generic controller mounted out where its easy to replace it. The little compact compressors of whatever brand have a dashboard for the gauges and shrouding over the controller so it seems that replacing the controller, perhaps a unique one, would be more difficult and possibly expensive.

But I am thinking of moving the HF compressor over to that adjacent barn stall to muzzle some of its racket!

 

[cqaigy2]

What I'm thinking is, those little 1HP/6gal "silent" import compressors may not put out enough air for a shop, may not be capable of continuous duty, may not last as long as a good quality one, etc., but...

At <$150 each, I could buy 5 of them, plumb them together along with my 26 gal craftsman acting as a storage tank, and I'd have:
5HP
56gal
15.5CFM @ 90PSI
125 PSI max
51db (whisper quiet)
... all For $750.
I could connect an analog pressure sensor to a little programmable control board like an Arduino, which would track the run time of each compressor and when the pressure drops below, say 120PSI, it could switch on a single compressor, whoever has the lowest hours. And if it drops below 115PSI, it can switch on a 2nd compressor, the next-lowest-hours compressor, and so on in cascading fashion until all 5 compressors are running in response to a large air demand. This way none of the compressors has to run continuously and as long as air demand is minimal (which is usually), the run time will be divided among 5 compressors, theoretically extending their lifespan by up to 5X. There is the added benefits of having FIVE levels of redundant backup, being able to easily detach a part of your air system and take it on the road, and if a compressor fails you just replace it for $150 and leave the tank connected to your system, so if ever you do experience a failure it's not a total loss; your volume grows with each failure.

Compare that to a quincy such as this:
$1,399
5HP
60Gal
15.4CFM @ 90 PSI
175PSI max
75db (super loud)
Single point failure if the compressor goes out

The only area I see the Quincy winning in, is max PSI, and I never use more than 100 PSI, so I don't see the justification in paying the extra $650.
(oh yeah, and 4 gal more storage)

You do this, you HAVE to do pictures and a write up.

 

[strantor]

You do this, you HAVE to do pictures and a write up.

I plan on it, but not until next year. If I'm not destitute after Uncle Sam is done with me.

 

[Michael Aos]

I have a California Air Tools. I haven't used it a lot, but I've been happy with it so far. I noticed Harbor Freight has a new quiet offering now too.

 

[fried1765]

What I'm thinking is, those little 1HP/6gal "silent" import compressors may not put out enough air for a shop, may not be capable of continuous duty, may not last as long as a good quality one, etc., but...

At <$150 each, I could buy 5 of them, plumb them together along with my 26 gal craftsman acting as a storage tank, and I'd have:
5HP
56gal
15.5CFM @ 90PSI
125 PSI max
51db (whisper quiet)
... all For $750.
I could connect an analog pressure sensor to a little programmable control board like an Arduino, which would track the run time of each compressor and when the pressure drops below, say 120PSI, it could switch on a single compressor, whoever has the lowest hours. And if it drops below 115PSI, it can switch on a 2nd compressor, the next-lowest-hours compressor, and so on in cascading fashion until all 5 compressors are running in response to a large air demand. This way none of the compressors has to run continuously and as long as air demand is minimal (which is usually), the run time will be divided among 5 compressors, theoretically extending their lifespan by up to 5X. There is the added benefits of having FIVE levels of redundant backup, being able to easily detach a part of your air system and take it on the road, and if a compressor fails you just replace it for $150 and leave the tank connected to your system, so if ever you do experience a failure it's not a total loss; your volume grows with each failure.

Compare that to a quincy such as this:
$1,399
5HP
60Gal
15.4CFM @ 90 PSI
175PSI max
75db (super loud)
Single point failure if the compressor goes out

The only area I see the Quincy winning in, is max PSI, and I never use more than 100 PSI, so I don't see the justification in paying the extra $650.
(oh yeah, and 4 gal more storage)

Your proposal is a "theory"
Who is actually going to DO it ??

 

[strantor]

Your proposal is a "theory"
Who is actually going to DO it ??

I am. Next year, if someone doesn't beat me to it.

 

[kc5dlo]

I got this from my grandpa. Its quiet enough you can watch tv in the next room. I use it for things around the house away from my garage. I guess its quiet because of how slow it runs?

Or put the loud one outside in it's own enclosure.View attachment 575768

Anyone know where I can get another braided cloth air hose? I like this one alot. I know it's old though.

I have a similar model at my city house. Very quiet indeed. Same size oil less compressor would have my neighbors complaining.

 

[sd455dan]

Interesting concept, a couple concerns- and I am sure I am probably being overly critical on this...


If using high demand tools for long periods (as an example a D/A sander) will likely push them all into continuous duty at the same time.



Most belt driven oil type pump compressors are rated for continuous duty (both the pumps and motors)
So if needed you can and likely will- run them non stop, don't have to worry about having to shut off the compressor to save either the pump or motor or being in the middle of an important job -say painting and have the compressor (gasp) turn off- to protect itself.

jmo but that would bother me more than the noise..

I run 2 parallel compressors ( IR 5 hp 60 gallon uprights) when needed.
They are not super quiet but run very smoothly and not what I would call irritatingly loud but surely louder than the small quiet compressors together. also provide 24+Cfm @90 psi If both are turned on.

Maybe these new direct drives are long lived but what I have been able to find for durability/ quoted lifespan it doesn't look real good...


15 cfm @90 psi that you quoted,using them in parallel sounds good, right up with the belt driven units

but wearing out or over working these small non continuous duty multiple motor/ pumps could be a reality.

I checked out California Air 4 hp quiet compressor for $1700....


it has a listed life cycle of 3000 hours... and it's competitors at less than 1500 hours
that is about about 1/8 of an average Quincy, IR or other name brand oil type belt driven compressor

if that is how long lived a $1700 direct drive oil less Quiet compressor is-

What can be expected out of a few sub $200 units hooked together?

California air quotes their small inexpensive line compressors at 3000 hours to which is a Good thing, with California Air asserting some competitors are less than 250 hour life cycle.

3000 hours to have a nice quiet compressor is probably worth it for many versus 25-50000 hours for a good brand name belt drive oil type that is louder.

the only thing that i would suggest with your plan/ build would be to buy compressors with a lifetime hour spec like California Air quoted so you can get decent service life from the multi compressor build.