Running compressor "too slowly"

I _may_ have an opportunity to pick up a compressor a bit "too large" for my needs at reasonable cost (depends on the bidding).
GRANTED (wanna bet some people ignore this part) that doing so will provide less air than the compressor is rated for, and GRANTED that I don't mind that, what actual problems would be encountered by running a 5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED (larger pulley on the compressor, or a jackshaft) such that the 2 or 3 hp motor is not being overloaded.
In engine service, lower speed is a good thing, so 3600 rpm motors wear out much faster than 1800 rpm motors.
What, other than reduced air output that I'm willing to accept, are the actual downsides, if any, of running a compressor slower than it's "supposed" or rated to run?
Lack of fan action from the pulley is easily compensated by putting a fan on it, and heat production will be lower at a lower speed anyway.
Not enough "splashing" for splash lubrication? Something less obvious I can't think of?
While I could always harvest the large tank and try to flip the big motor and compressor for a smaller one, the less stuff I'm trying to swap, the better, generally.
--
Cats, coffee, chocolate...vices to live by

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Without getting into mechanical calculations, your premise sounds like it should work ok. I questioned the logic until I came to the part about "larger pulley on the compressor, or a jackshaft" in order to avoid overloading a motor of lesser hp. Others, better versed in compressor design, may have different ideas but my "knee jerk" is that you will be ok.
Bob Swinney
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Feb 6, 10:36 am, Ecnerwal

The big down side is the slower motor will run forever to pump up to the same pressure the faster motor gives.
Paul
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 06 Feb 2010 11:27:18 -0800, snipped-for-privacy@coinet.com wrote:

But that's exactly what you'd get with a smaller compressor run at a higher speed.
--
www.wescottdesign.com

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
At a speed below minimum, lubrication systems of compressors may not work properly. Splash lubricated compressor have little spoons that "splash" the oil around, and at low speed they would not be able to fling oil far enough. I am not sure about pressure lubed compressors, but they too have a minimum speed.
You can call the manufacturer and find out.
i
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Should have the same starting torque with a lower HP motor turning the compressor at a slower speed.
Dan
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Should have the same starting torque with a lower HP motor turning the compressor at a slower speed.
Dan *************************
And, the head will be unloaded...I assume.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not many motors or compressors like starting under load.
I've known of people (like me) to use refrigerator compressors as air compressors. There are a few technical things, like change the oil. A quiet running refrigerator compressor works nicely, if you start it with zero back pressure.
A compressor out of a HVAC unit might work, also.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I don't know if you're concerned about efficency but the larger compressor will have more friction loss than outputting the same CFM's with a smaller compressor because of larger piston contact area, larger bearing area ETC. Also there is more power loss compressing air into the inevitally larger space above the piston that must be pressurized before the outlet check opens.
Engineman
On Feb 6, 11:31�am, Ignoramus20464 <ignoramus20...@NOSPAM. 20464.invalid> wrote:

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is it splash lubed or oil pumped? Bigger pumps usually have an oil pump. I run my Quincys way slower than max, they will last forever. I think you will not only NOT have a problem, you will LIKE the way it runs quiet and cool.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Now HOW do you know they'd last any longer? A Quincy will last forever anyway.
But, I think the OP has a good idea. gear it down to the smaller motor.
Karl
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

In 35 years, I have had to replace 2 wrist pins, 1 HP piston, numerous valve bodies, a bunch of valve disks, 3 sets of rings, various oil pump rebuilds and a boatload of gaskets. But, that's on four pumps and mostly due to the "Run em till they die" maintenance program. Now, we actually keep them clean so they cool better, run them slower, change the oil using synthetic and keep up on the leaks.
Don't forget I need a ship-to address if you want some 9mm cast.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for the remind. I was a bit <very> distracted when you first offered. You got email.
Karl
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There's plenty of load info on the web but if he needs any more, I've got plenty of books. I'm still working my loads for my 9's, I use IMR 700x, most people don't. But so far, I like the projectile though it's not the easiest to cast, probably because it's so small.
It seems like anytime I need Gunner's wisdom, the bastard's out of town!
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Son...the phone is close to your hand. Use it
805-732-5308
Just keep in mind Im living on PST...and dont do "early" very well, but I live in "late". <G>
Gunner
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You're just saying that 'cuz I woke you guys up at some ungodly hour on a Sunday morning. I STILL feel bad about that! I keep forgetting about that pesky time-zone thing.
OK, I think I have an extractor problem on my 1911. I bought it used with what the guy said had only 100 rounds through it. Everything points to that being the truth except the extractor looks like somebody attacked it with a file. With factory ammo, it gets 5% FTF. I have yet to get my reloads to feed right with a 200gr. SWC Keith. On the web and in my books, I see all different kinds of OALs. What specs do you use for this bullet? What should I do about the extractor? I'll try to get some pix with my new, WAY-COOL, USB 200 power video/still microscope.
I do have my .38 load dialed in! I put 100 rounds through a 1" hole from a rest. 3.0 gr. 700x 148gr. DEWC. I use 1 part Alox in 6 parts mineral spirits and it looks like thin wood stain. It's hardly noticeable on the bullets and dries hard. It WORKS! No lead, no smoke, no residue!
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am the same way.

My solution to pesky early morning phone calls, is that I installed a "whole house phone switch", and when I flip it, landlines are turned off. (and for those wishing to lecture me on safety, we have cell phones)
i
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus30280 wrote:

Who cares?
--
Greed is the root of all eBay.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I seat em with about 1/16" of lead bullet shoulder showing at the mouth of the case.
5%?.....tried changing recoil springs? Go down a couple pounds. The weapon was set up to be a combat arm..and if you are loading target velocity ammo..feed problems are likely.

Noted! Thanks!!
Gunner
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Will do.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.