Scroll Compressors

[Jim Tobias]

Educate me about scroll compressors and can they replace a regular compressor in a woodworking shop??

Thanks,
Jim

[Tom M King]

Not for a home shop. They are designed to, and are better off, running all the time, or at least, that's what I've always been told.

[Jim Tobias]

What got my attention about these was the very low noise level and the high CFM. I wanted to use it with air sanders.
Jim

[Malcolm McLeod]

Not for a home shop. They are designed to, and are better off, running all the time, or at least, that's what I've always been told.

+1 - They are great, if run for 'long' periods. They have to heat to their normal operating range of 170-180dF.

Typically, they inject lube oil at the inlet of the scroll(s), which mixes with the intake air - and any water vapor (humidity) the air contains. This mix of air/water/oil gets discharged from the scrolls to a separator - and depending on temperature and pressure, the 'humidity' may be water. If water, it gets entrained with the oil and recirculated - with reduced lubrication =>> bad! If the unit runs long enough, you get higher temperatures and so no water condensation. If still vapor, the water gets carried thru the system with the air and can be removed via typical dryers, filters, etc. further downstream.

We just pulled 2 barely used Atlas-Copco 5hp screw units off a site, one only had 144 hrs on it, but they'll go into 'storage' until they get sold for scrap. I was tempted to try to purchase it, but just don't use enough air in my shop to fight the entrained water. Que sera.

[Richard Coers]

The price always turned me away. $3,000 to start. I've got a 2 stage compressor from the days I ran a business. But much prefer electric sanders these days.

[Jeff Monson]

Like others have stated, they are designed for high volume air use, constant duty cycle. I have looked at them a couple different times as I own a shop and our compressor runs quite often. Every time the salesman steers me away from a screw compressor and more toward a high cfm piston pump with a large tank. For home use I have a flexzilla 220 volt 80 gallon compressor, noise level is very low as that is their selling point, very happy with it. I do have it in a utility room but can hardly hear it.

[Bill Dufour]

Look at the cost and frequency of oil and filter changes. In a shop you need extra tank storage so they run at least 15-30 minutes at a time every time.
Bill D.

[Ronald Blue]

My service truck has a scroll style VMac compressor. It's a beast. It will maintain high air volume and pressure together. Because it's hydraulically driven it's not quiet. It does have a "warm up cycle" and will run for probably 15 minutes before shutting off. One of our shops has a scroll compressor. It is as said very quiet and maintains pressure effortlessly. Much of the time we use only small amounts of air. I'm not aware of any issues because of this. It's been in service for at least 10 years. It is maintained/checked regularly. There is no question that they can supply a large volume of air. I suppose it's a case of balancing your needs. They have been around for a long time. They have oil free units as well. Not arguing whether they are or are not acceptable for a home shop just that they have plenty of good points.

[Tai Fu]

Do you mean screw compressor?

I used to use my neighbor's screw compressor and aside from the insane amount of CFM it produces at very low noise levels, I can't tell a difference. Compressed air is compressed air.

But they're also insanely expensive so if you can afford them, go for it. As for maintenance I don't know if they are more expensive than regular reciprocating compressor, but for low duty usage a reciprocating compressor of the right CFM is more than enough.

Neighbor use it for VMC's, but honestly they don't really need that much air, but they leak a lot so the extra cfm is needed to keep it running right.

[Tom M King]

There are both scroll compressors, and screw compressors.

edited to add: I did see that Eastwood is selling an interesting looking little scroll compressor, but don't know anyone that has one.
https://www.eastwood.com/eastwood-elite-qst-30-60-quiet-scroll-air-compressor-nv.html?gclid=CjwKCAjw1JeJBhB9EiwAV612yw2hSk2kF4Z-zUmOCGSVPeIAaPHj8XvlaRu2h97l5lOkAoFmG7tlsxoCwmEQAv D_BwE&wickedid=414412145471&wickedsource=google&wv=3.1

[Adam Herman]

There are both scroll compressors, and screw compressors.

edited to add: I did see that Eastwood is selling an interesting looking little scroll compressor, but don't know anyone that has one.
https://www.eastwood.com/eastwood-elite-qst-30-60-quiet-scroll-air-compressor-nv.html?gclid=CjwKCAjw1JeJBhB9EiwAV612yw2hSk2kF4Z-zUmOCGSVPeIAaPHj8XvlaRu2h97l5lOkAoFmG7tlsxoCwmEQAv D_BwE&wickedid=414412145471&wickedsource=google&wv=3.1

a few youtube automotive guys have them, and from what i can tell they are great. low noise, high volume and reliable.

[Malcolm McLeod]

There are both scroll compressors, and screw compressors.

edited to add: I did see that Eastwood is selling an interesting looking little scroll compressor, but don't know anyone that has one.
https://www.eastwood.com/eastwood-elite-qst-30-60-quiet-scroll-air-compressor-nv.html?gclid=CjwKCAjw1JeJBhB9EiwAV612yw2hSk2kF4Z-zUmOCGSVPeIAaPHj8XvlaRu2h97l5lOkAoFmG7tlsxoCwmEQAv D_BwE&wickedid=414412145471&wickedsource=google&wv=3.1

Oops.:o Sorry, Mr. Tobias. I read 'scroll' and mentally leaped on 'screw'. (Scroll are quiet and nearly oil free, but not high volume. Relative to Hp. And the discharge air needs a cooler, IIRC :: they get HOT.)

*** Never 'used' scroll compressors personally, just been around them in the occasional lab environment.

[Albert Lee]

I had a Hydrovan 43 compressor, 7.5kw unit I believe it was, its quiet, the humming noise it makes feels like a large old fridge, I think the noise level is similar to a rotary screw compressor.

The service is expensive. I bought it for $1000, service cost $700. I ditched it and bought a new silenced piston compressor. less hassle, less maintenance. and easily repaired/replaced parts if required.

[Tai Fu]

Yea I heard scroll compressors are REALLY hard to service, needs specialized services which costs money. I think this applies to screw compressors too. My neighbor's compressor costs 5000, not including a tank. The service costs 150 each time. It needs special service (the compressor's computer will lock out after a x number of operating hours) even for oil change (which is the cost of the service). Also the screws/scrolls are matched to each other so you simply can't just go buy off the shelf part, remachine things, etc. to get it working again.

I have a lower RPM piston compressor. They aren't terribly loud, and if you want to silence it, you can either enclose it or do some other thing (use a VFD for example to further reduce cfm/rpm) to make it not so loud. Piston compressor is also not hard to maintain at all.

The one I have has 3x 80mm (I think) cylinders. Compressor is 5HP, runs at around 800rpm. It gives about 25CFM here, but let's say you want a 5HP compressor that is quieter (and most 5HP compressor have lower RPM and therefore quiet) you can perhaps find larger piston pumps, say the kind found on a 10HP compressor, but instead of running them at 800 RPM you run them at 400 RPM. There will be very little noise and it will still pump about 25cfm. Or use a VFD if you really don't need 25CFM and reduce the speed further to make it quiet.

That and piston compressors last a long time.

[Curt Harms]

..........................
Compressor is 5HP, runs at around 800rpm. It gives about 25CFM here, but let's say you want a 5HP compressor that is quieter (and most 5HP compressor have lower RPM and therefore quiet) you can perhaps find larger piston pumps, say the kind found on a 10HP compressor, but instead of running them at 800 RPM you run them at 400 RPM. There will be very little noise and it will still pump about 25cfm. Or use a VFD if you really don't need 25CFM and reduce the speed further to make it quiet.

That and piston compressors last a long time.

If you have access to a large safe (not rusted) pressure tank and/or suitable motor, using an oversized air pump and slowing it down seems like an interesting idea. Air pumps aren't very expensive and with reduced RPMs they'd probably last forever. Of course it matters who makes said air pump, I imagine Quincy would be a bit more $$ than Harbor Freight.