10Hp screw compressor for small shop?

Hey guys!
At the moment I am running my shop off a decent quality 5HP piston compressor, but I just hate how loud it is... A while back I got a good deal on a used Kaeser SM10 'aircenter' screw compressor, but it has sat for the last year without being wired up as it's 600V and everything else in my shop is 208V.

I'll be moving to a new shop next month and I'm trying to decide on which compressor should go with me. I can only take one as the new shop is smaller than my current one and I'm getting rid of unused equipment to make everything fit. Do I take the Kaeser, or try to find a smaller screw or something else?

I *need* a quiet compressor. I'm going to annoy neighbours (and myself) in the new building if I keep running the piston compressor, but I'm worried that this 10HP Kaeser might be 'too much compressor' and drive my power bills up significantly, or that it might not run enough (I keep hearing that screw compressors can have their lifespans shortened if they don't run enough).

Usually my 5HP piston only runs about once per hour, but 2-3 times a week I need to use my sandblasting cabinet which will keep the compressor running constantly for an hour or so while using the cabinet. The inconsistent demand for air leaves me in a weird place where 95% of the time even a small pancake compressor would keep up, but they other 5% of the time I could actually use more than 5HP...

So I guess my questions are:
- Will a 10HP screw drive my electrical bill up an unreasonable amount if I usually don't need that much air?
- Will running a screw compressor for only ~5 minutes per hour shorten it's lifespan?
- Are there other options I should look at?

That Eastwood scroll compressor that has been getting posted recently caught my attention pretty fast, but it's a little undersized for my sandblasting needs, I would have to get two of them... I did price out a 5HP screw new from Kaeser and came away from that with severe sticker shock, especially compared to what I paid for the 10HP...

If anyone has a 5HP screw in good condition and wants to trade up to a 10HP I would certainly consider that as well!
-Aaron

One thought that just occurred to me: maybe I'd be better off getting a really small compressor to run my 2 VMCs (which only really use air during tool changes), and hook the Kaeser directly up to the sandblasting cabinet? That way it wouldn't go through the warmup and unload cycle each time the VMCs need air?

A large receiver (tank) and proper pressure set-points and regulators can help, but at the end of the day, you have two very different air needs, and none are continuous.
How many how’s per day / week do you sand blast? Would the Eastwood and a big tank get you through a session?
I was surprised a Fadal can run off a small pancake compressor.
I’m in a similar boat, my bigger compressor is dying and both it and the pancake are too loud because I can’t seem to sleep anymore and want to work at 4:00am
Im 95% sure I’m getting that Eastwood, but still looking local, hard to find anything good that’s good but not a monster.


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I use a Jun-Air cabinet style compressor to run machine actuators and chip blowers. Super quiet machine built to run in commercial settings. It has an on board dryer and air cooler. It’s something around 50Db so I can run it at midnight and no one notices.

I would just get a large (like 120gal) auxiliary tank and hook it up to the Kaeser. The Kaeser will want to run for several minutes at a time so it heats up, as opposed to frequent short bursts, but it should be happy to just sit between cycles.

This way you can run the VMC's for a long time without a compressor running at all since they will just be pulling out of the auxiliary tank.

Regards.

Mike

Finegrain said:

I would just get a large (like 120gal) auxiliary tank and hook it up to the Kaeser. The Kaeser will want to run for several minutes at a time so it heats up, as opposed to frequent short bursts, but it should be happy to just sit between cycles.

This way you can run the VMC's for a long time without a compressor running at all since they will just be pulling out of the auxiliary tank.

Regards.

Mike

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Thanks Mike! That sounds like it would work well, and I could keep my piston compressor as a backup and use the tank to fill that role as it has a 90 gallon tank.

My main concern with that approach is simply space... My new space will only be ~550sq ft so having the extra tank will eat up valuable space unfortunately. The screw compressor does have a 70 gallon tank built into it, but I know larger would be better...

Is the Kaeser capable of being changed over to run on 208V, or was you planning on using a transformer?

It may be possible to jump on eBay and find a new (or nearly new) 5 or 7.5hp 208V motor, and run the Kaeser with that.

May have to reduce motor-pulley size, or max. pressure?

I know my Quincy dual-stage piston compressor is rated for 7.5 to 20hp motor, requiring a change of motor pulley size for different hp...

I’ve got him running on a 7.5hp WEG motor, driven by a Mitsubishi inverter, for smooth startups.

ToolCat Greg

cnctoolcat said:

Is the Kaeser capable of being changed over to run on 208V, or was you planning on using a transformer?

It may be possible to jump on eBay and find a new (or nearly new) 5 or 7.5hp 208V motor, and run the Kaeser with that.

May have to reduce motor-pulley size, or max. pressure?

I know my Quincy dual-stage piston compressor is rated for 7.5 to 20hp motor, requiring a change of motor pulley size for different hp...

I’ve got him running on a 7.5hp WEG motor, driven by a Mitsubishi inverter, for smooth startups.

ToolCat Greg

Click to expand...

I asked the local Kaeser guys if I could convert it to 208V but they said a transformer was the only option. I doubt it's actually the only option but they certainly don't seem to want to do an actual conversion.

The new shop will have 575V coming into the unit so I will be able to get the electrician to install a splitter and disconnect just for the compressor.

If anyone has done a voltage conversion or a motor size swamp on a Kaeser I would definitely love to hear more about that!

ripperj said:

A large receiver (tank) and proper pressure set-points and regulators can help, but at the end of the day, you have two very different air needs, and none are continuous.
How many how’s per day / week do you sand blast? Would the Eastwood and a big tank get you through a session?
I was surprised a Fadal can run off a small pancake compressor.
I’m in a similar boat, my bigger compressor is dying and both it and the pancake are too loud because I can’t seem to sleep anymore and want to work at 4:00am
Im 95% sure I’m getting that Eastwood, but still looking local, hard to find anything good that’s good but not a monster.

Click to expand...

My sandblasting needs are pretty modest, I'm usually only blasting 4-5 knives at a time so in regular production I'd likely only be blasting for about 45-60 minutes a day a couple of days per week.

Right now I'm using a nozzle that requires about 20CFM, but I could certainly go with a little bit of smaller nozzle to get my air needs down. Minimum is about 12CFM though, and the eastwood won't quite keep up with that while also keeping the VMCs fed unfortunately.

I love the build quality and size of the Kaeser, if it was 5HP and 208V I would have zero concerns, just when I bought it I thought I was going to need more air than I actually do...

Possible to sell it and buy a smaller one? I wanted to buy a Kaeser but after speaking with the company they suggested I would not be using it enough and it would be highly problematic.

I also use Jun-Air cabinet style compressor.

The guys running Jun-airs, what did that setup cost? A quick perusal online shows 2hp for about 10 grand, which is... steep.

BHolcombe said:

they suggested I would not be using it enough and it would be highly problematic.

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I keep hearing this from some vendors and then others say it's fine, but that you'll waste some energy because the compressor will spend a higher percentage of it's time running the warmup and unload cycles...

Does anyone know for sure whether or not it's ok to run a screw compressor at a low duty cycle?

WRT Jun-Air: Buying new they’re expensive, I bought one with 3500hrs on it in good shape then did the typical maintenance on it. I paid about 10% of new.

I also had to find replacement parts, there is a European seller that is super reasonable and many other parts are available through sources like mouser/galco.

One part was quoted to me at $800, I found it on Galco for $55.

Great compressor, my shop air is clean, dry and cool.

aarongough said:

I keep hearing this from some vendors and then others say it's fine, but that you'll waste some energy because the compressor will spend a higher percentage of it's time running the warmup and unload cycles...

Does anyone know for sure whether or not it's ok to run a screw compressor at a low duty cycle?

Click to expand...

Mine, and probably Kaeser as well, have a significant run-on timer to keep everything going for a few minutes after the high pressure switch trips. This is to ensure all the moisture in the air end is boiled off before the machine stops.

This is another reason for a large auxiliary tank -- the run-on happens much less frequently so the overall duty cycle of the motor and air end is much lower. I figure I will have paid for my 120 gallon auixiliary tank in ~2 years just from electricity savings. Without the aux tank, my 5 kW Atlas Copco would pump up for ~2 minutes then run on for 6 minutes. With the aux tank, it';s more like 8 minutes and 6 minutes.

Regards.

Mike

The Kaeser compressors are a great machine that said I am not entirely sure you would want to run it on a step up transformer.
Especially if it's a later Kaeser with Sigma control. I believe it would be opening a major can of worms attempting to swap motors they spin at a higher RPM then standard 1800/3600 motors, changing pulleys just creates even more problems.
As for life span the Kaeser will pretty much run forever with good maintenance, even cycling often.
We run several Kaesers Much larger units that have twin 280 gallon tanks on each. One of our retired units had close to 25,000 hours on it and was still working good when we removed it, the dealer I traded it in to sold to somebody else.

Another approach would be to quiet down the 5hp recip. Most of the noise is generated at the air INLET, so install a 'muffler' on the intake. I bought one from a Quincey dealer (Brehob Electric, Indy). Looks like a two foot long eight inch diameter filter. Noise reduction was unbelievable!

I run an Kaeser SM10 air center. I bought it used with about 7k hours on it. The unit is in the same room as my CNC's, and I have an 80 gallon expansion tank at the other end of the building, next to my Jig Grinder. The unit is quiet and efficient, the chiller works great, and it expels any water in the system automatically (hose into a used 5 gal coolant bucket). I wish I had done it years ago. Parts are expensive, but, so far every issue has been solved over the phone, with next day delivery of Parts. (Dealer in Syracuse, shop in Utica) Good luck. Chris

aarongough said:

I keep hearing this from some vendors and then others say it's fine, but that you'll waste some energy because the compressor will spend a higher percentage of it's time running the warmup and unload cycles...

Does anyone know for sure whether or not it's ok to run a screw compressor at a low duty cycle?

Click to expand...

I ran a used Kaeser I purchased off Ebay with a pretty low duty cycle for 2 years without a single issue. I had a small 15 gallon auxillary tank next to the machine and probably 90ft of 3/4" copper line between the main tank and the machine. Go with the Kaeser, they are tanks.

Red James said:

Another approach would be to quiet down the 5hp recip. Most of the noise is generated at the air INLET, so install a 'muffler' on the intake. I bought one from a Quincey dealer (Brehob Electric, Indy). Looks like a two foot long eight inch diameter filter. Noise reduction was unbelievable!

Click to expand...

Do you have any numbers on how much it reduced the noise by? I would happily stay with the piston compressor if I could get it quiet enough... Overall I would prefer to keep the piston over the screw because I know if something goes wrong it will be easy to diagnose and relatively cheap to fix. It's just the noise I can't live with.