# New compressor landed today.



## diamond (Sep 16, 2021)

Moved recently to a home in Prescott AZ with a nice shop building.  Left my 7hp noisy beast of a compressor back in the old shop in CA.  I went back and forth a lot on what to buy but I knew I wanted quiet.    Finally settled on a CAT 4hp 60 gallon with auto drain and it arrived today.

I was (and still am) a little nervous about going oil-less.   Will it really be quiet?  Will it last?

However after firing this thing up for the first time, I was shocked about one thing.   It really is amazingly quiet!   

Time will tell on the lasting part.  I don't do much extensive work so I expect this won't see much of a duty cycle.   Mostly it's for blowing chips, running tool changer on my mill, fog buster etc.   I do occasionally run small air tools and I do have a small sand blasting cabinet (I've never used).  I wanted the larger capacity in case I do start doing more.

I have it in the area underneath the stairs going to the shop loft.   I planned to put a door on the opening to contain noise but now I'm thinking I won't.  It'll get better ventilation that way and the sound is hardly noticeable walking around the 1100 sqft shop.   Even standing in the contained space under the stairs it's not bad.  That old compressor would have been painful in there.

Next up is plumbing the Maxline, manifolds and filters.  After I get some pads and bolt it down.   Though there's really no vibration when it's running.  

I'd say for the first look at this thing, I'm cautiously impressed.


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## woodchucker (Sep 16, 2021)

yea those are nice units. Good luck.


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## brino (Sep 16, 2021)

I think my next compressor will be from them.
Is yours an aluminum tank?

That rust-proof feature is one that might make it my last compressor too!

-brino


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## NCjeeper (Sep 16, 2021)

That thing is sweet.


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## hman (Sep 16, 2021)

@brino - I checked both the CAT site and Amazon.  The tank is steel.








						California Air Tools - The Largest Manufacture of Ultra Quiet, Oil-Free & Lightweight Air Compressors - CAT-60040CAD
					

New page




					www.californiaairtools.com
				





			Amazon.com


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## woodchucker (Sep 16, 2021)

I think steel is better, they say the AL tanks are more brittle and subject to cracking with repeated cycling. I don't know if it's true, but I believe it to be true.


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## FOMOGO (Sep 16, 2021)

Nice for light use, and the noise level is definitely a plus, but not nearly enough cfm for my needs. Mike


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## brino (Sep 16, 2021)

hman said:


> I checked both the CAT site and Amazon. The tank is steel.





woodchucker said:


> I think steel is better, they say the AL tanks are more brittle and subject to cracking with repeated cycling. I don't know if it's true, but I believe it to be true.



Thanks guys!

Has anyone seen data on aluminum tank longevity?
Does any supplier offer a stainless steel tank? I would pay double!
I fear that just like other places it makes great sense (vehicle brake lines and exhaust) that it will be unobtainium (either totally unavailable or 50x the price).

-brino


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## MikeInOr (Sep 16, 2021)

2 x 2hp 1700rpm motors with 2 single stage pistons per motor.  10cfm @90psi.  That certainly sounds like it would run most any air tool I have.  I wonder if it would keep up with a blasting cabinet?


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## markba633csi (Sep 16, 2021)

Very handsome compressor indeed- looks like it's all dressed up, top hats and tails
-M


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## diamond (Sep 17, 2021)

markba633csi said:


> Very handsome compressor indeed- looks like it's all dressed up, top hats and tails
> -M


LOL



woodchucker said:


> I think steel is better, they say the AL tanks are more brittle and subject to cracking with repeated cycling. I don't know if it's true, but I believe it to be true.


Yes steel.  I had the same thoughts.  Also living in Arizona I figured it'll be a little dryer here most of the time.


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## diamond (Sep 17, 2021)

MikeInOr said:


> 2 x 2hp 1700rpm motors with 2 single stage pistons per motor.  10cfm @90psi.  That certainly sounds like it would run most any air tool I have.  I wonder if it would keep up with a blasting cabinet?


My blasting cabinet is small one from HF.   I think it will but when I get it up and running I'll update.  Might be a while tho.   Have a few other machines to get up and running first.


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## FOMOGO (Sep 17, 2021)

I have one compressor in the old shop that puts out 21cfm at 175 psi, and it won't quite keep up with my large bead blast cabinet. In the new shop I will have three compressors linked for a large blast setup in a container outside. The great majority of the time one unit will be sufficient for my needs. Mike



MikeInOr said:


> 2 x 2hp 1700rpm motors with 2 single stage pistons per motor.  10cfm @90psi.  That certainly sounds like it would run most any air tool I have.  I wonder if it would keep up with a blasting cabinet?


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## addertooth (Sep 17, 2021)

I have a California Air Tools compressor as well.  It is a smaller model with Aluminum tanks (no problems with the tank, and no risk of water making the tanks "rust through").   It is a CAT-4610a, and is twin cylinder with two tanks of 2.3 gallons each.   It has been solid in it's performance.  It is only about 2.2 CFM at 90 PSI.


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## MtnBiker (Sep 17, 2021)

MikeInOr said:


> 2 x 2hp 1700rpm motors with 2 single stage pistons per motor.  10cfm @90psi.  That certainly sounds like it would run most any air tool I have.  I wonder if it would keep up with a blasting cabinet?


I'll be Captain obvious here but cfm ratings are kind of a best case. The way you route the air is important. Directly connected air lines vs long runs, filters, bends, etc. The diameter of the lines too. All that said, those CAT compressors are really quiet which is nice if you don't have an out building.

Oh...and rig up an after-cooler/separator between pumps and tank if you care about tank longevity.


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## diamond (Sep 17, 2021)

MtnBiker said:


> I'll be Captain obvious here but cfm ratings are kind of a best case. The way you route the air is important. Directly connected air lines vs long runs, filters, bends, etc. The diameter of the lines too. All that said, those CAT compressors are really quiet which is nice if you don't have an out building.
> 
> Oh...and rig up an after-cooler/separator between pumps and tank if you care about tank longevity.



I hear you about the routing affecting CFM.   My HF sand blast cabinet says it requires "average" 9.5 CFM.  I don't know what the min/max of that average is.  So it's kind of up in the air (pun intended) if I'll have enough. I'll be running 3/4" Maxine.  My longest run should be about 40' or so and the blast cabinet will be at the end of that.   If I ever get around to using it I'll find out.   But for everything else I do, this is likely more than enough.

Perhaps one beef about the CAT, the tank has a 1/2" outlet and that came came from the factory reduced to a 3/8" filter/reg.  That may be a choke point and I'm considering upping it to 1/2" but I wish it had 3/4" port in the tank to match the distribution.   Maybe matching the tank port to the same diameter as the distribution piping isn't an issue but in my mind I want to think it is.  

CAT has the same compressor with a dryer between the pumps and tank, but it's WAY more expensive!   CAT-60040DCADC  I hope I didn't fool myself but I decided I didn't need it at $3900 vs $1500.   I guess I'll monitor how much the auto drain puts out of the tank to see how much moisture is actually going in there to see if I need try to do something about it.   The model I have has some electronics (thermal overload detectors or something?) on the lines from the pumps to the tank as well as some depressurization valves that I guess are there to help the motor on startup.  I don't know how much of that I'd be messing up if I tried to put a cooler inbetween and void my warranty or mess up the pumps.  It's a bit different setup than the old Porter Cable I had with just a simple pipe from the pump to the tank.


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## tq60 (Sep 17, 2021)

Get one of the portable air tanks and place it under the blast cabinet keyed into the line.

It will maintain airflow allowing refill between trigger pulls

Sent from my SM-G781V using Tapatalk


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## kb58 (Sep 17, 2021)

I have the 2hp horizontal tank version of that. I'm happy with it... BUT, there was one time that I heard it click on, and instead of starting, the motor sat there, stalled. I quickly shut it off and of course it's worked ever since. It has, however, made me leery of leaving it unattended, even if it does have a thermal shutoff.

BTW, there's no excuse, since the 220V power cord plugs into an outlet about 3 feet from the main breaker box, so it's not an issue of the supply voltage dropping. I think that they size everything so that they motor is _just _enough to work.  They also have pressure vent valves, which vent the compressor outlet to atmosphere for a bit before imposing the compressed air's load onto the motor. Perhaps that valve didn't open. Since it only did it that one time (so far), it's hard to know what happened.

Raining on people's parades is what I do


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## MtnBiker (Sep 17, 2021)

diamond said:


> I hear you about the routing affecting CFM.   My HF sand blast cabinet says it requires "average" 9.5 CFM.  I don't know what the min/max of that average is.  So it's kind of up in the air (pun intended) if I'll have enough. I'll be running 3/4" Maxine.  My longest run should be about 40' or so and the blast cabinet will be at the end of that.   If I ever get around to using it I'll find out.   But for everything else I do, this is likely more than enough.
> 
> Perhaps one beef about the CAT, the tank has a 1/2" outlet and that came came from the factory reduced to a 3/8" filter/reg.  That may be a choke point and I'm considering upping it to 1/2" but I wish it had 3/4" port in the tank to match the distribution.   Maybe matching the tank port to the same diameter as the distribution piping isn't an issue but in my mind I want to think it is.
> 
> CAT has the same compressor with a dryer between the pumps and tank, but it's WAY more expensive!   CAT-60040DCADC  I hope I didn't fool myself but I decided I didn't need it at $3900 vs $1500.   I guess I'll monitor how much the auto drain puts out of the tank to see how much moisture is actually going in there to see if I need try to do something about it.   The model I have has some electronics (thermal overload detectors or something?) on the lines from the pumps to the tank as well as some depressurization valves that I guess are there to help the motor on startup.  I don't know how much of that I'd be messing up if I tried to put a cooler inbetween and void my warranty or mess up the pumps.  It's a bit different setup than the old Porter Cable I had with just a simple pipe from the pump to the tank.


YMMV...but here is my after-cooler install if it helps: https://www.hobby-machinist.com/threads/dry-shop-air-step-1-compressor-after-cooler.94795/

Total cost for all of it was about $225


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## diamond (Sep 17, 2021)

kb58 said:


> I have the 2hp horizontal tank version of that. I'm happy with it... BUT, there was one time that I heard it click on, and instead of starting, the motor sat there, stalled. I quickly shut it off and of course it's worked ever since. It has, however, made me leery of leaving it unattended, even if it does have a thermal shutoff.
> 
> BTW, there's no excuse, since the 220V power cord plugs into an outlet about 3 feet from the main breaker box, so it's not an issue of the supply voltage dropping. I think that they size everything so that they motor is _just _enough to work.  They also have pressure vent valves, which vent the compressor outlet to atmosphere for a bit before imposing the compressed air's load onto the motor. Perhaps that valve didn't open. Since it only did it that one time (so far), it's hard to know what happened.


Good to know, thank you for sharing @kb58 .   I typically don't leave my compressor on when I'm not in the shop but I'll be watching for that.  Did you contact CAT about it?  I'm curious to know what they might have said if you did.



MtnBiker said:


> YMMV...but here is my after-cooler install if it helps: https://www.hobby-machinist.com/threads/dry-shop-air-step-1-compressor-after-cooler.94795/
> 
> Total cost for all of it was about $225


Hey @MtnBiker  nice build.  I'll have to check into Hose Power.  I noticed the comments you shared about not really needing the after cooler for very intermittent compressor use (my use case primarily).  Unless I read that wrong.    I am looking into building a dryer manifold *after* the tank but that's not about protecting the tank of course.  I'm hopeful the auto drain on the tank will suffice but I'll have to watch to see.


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## MtnBiker (Sep 17, 2021)

diamond said:


> Good to know, thank you for sharing @kb58 .   I typically don't leave my compressor on when I'm not in the shop but I'll be watching for that.  Did you contact CAT about it?  I'm curious to know what they might have said if you did.
> 
> 
> Hey @MtnBiker  nice build.  I'll have to check into Hose Power.  I noticed the comments you shared about not really needing the after cooler for very intermittent compressor use (my use case primarily).  Unless I read that wrong.    I am looking into building a dryer manifold *after* the tank but that's not about protecting the tank of course.  I'm hopeful the auto drain on the tank will suffice but I'll have to watch to see.


There are some misconceptions about after-coolers. If you are only using air out of the tank after it has cooled and the pump is not turning on while you are using that cooled down air, then you don't need an after cooler. An auto drain will accomplish the same thing.


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## diamond (Sep 18, 2021)

Ah I see.  I was not thinking about that correctly.  In my usual use case the pump should not be running often.     

You've got me rethinking where I want to go with a DIY project.  I still don't think this would have pushed me to spend more than twice as much to have the version of this compressor with the dryer system from CAT.  That is over 2 grand more!  I may eventually end up with both types but reconsidering if building a cooler between pump and tank is more the priority now.   

I'd have to talk to the folks at CAT to see if they'll provide any advice on that front.  With the two pumps & the electronics there is a bit more  involved on this compressor vs just the usual tube from the pump to the tank.


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## 7milesup (Sep 18, 2021)

MtnBiker is correct.   You want the after cooler between the pump and tank.  I built a cooler for my compressor utilizing two home air conditioner coils (A-coils) stacked vertically.  I went with the air conditioner coils because I knew that they can handle high pressure vs other options.  I used copper line going from the pump to the top of the cooler.  Placing a drain leg at the bottom of the cooler is key.  I get a lot of water in the drain leg but virtually zero in the tank.

Regarding steel vs aluminum tanks, I would be uncomfortable with a large aluminum tank unless it had significantly thick walls.  Aluminum fatigues with pressurization cycles.  The Aloha Airlines incident comes to mind.   Aloha Airlines Explosive Decompression


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## MtnBiker (Sep 18, 2021)

diamond said:


> Ah I see.  I was not thinking about that correctly.  In my usual use case the pump should not be running often.
> 
> You've got me rethinking where I want to go with a DIY project.  I still don't think this would have pushed me to spend more than twice as much to have the version of this compressor with the dryer system from CAT.  That is over 2 grand more!  I may eventually end up with both types but reconsidering if building a cooler between pump and tank is more the priority now.
> 
> I'd have to talk to the folks at CAT to see if they'll provide any advice on that front.  With the two pumps & the electronics there is a bit more  involved on this compressor vs just the usual tube from the pump to the tank.


Plasma, especially long runs on a CNC, and any serious painting are two use cases that probably justify an after-cooler. The pump is on for an extended period. If it is low volume stuff just slap some filtration on there...maybe a cheap desiccant dryer. A longer run from compressor to filters, especially with something like copper tube, will allow more cooling and eliminate more condensate. Nobody dies in this scenario.


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## Firstram (Sep 19, 2021)

diamond said:


> the dryer system from CAT.  That is over 2 grand more!


You can build something very nice for much less $$$


diamond said:


> With the two pumps & the electronics there is a bit more  involved on this compressor vs just the usual tube from the pump to the tank.


I'm really curious about this, is there more than one tank inlet? All you need to do is intercept the air before the tank to cool it. The electronics don't/shouldn't know where the air goes.

Not knowing where you live or your air needs, you may not really need to address the humidity problems. Hook it up and enjoy it!


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## diamond (Sep 19, 2021)

Firstram said:


> You can build something very nice for much less $$$
> 
> I'm really curious about this, is there more than one tank inlet? All you need to do is intercept the air before the tank to cool it. The electronics don't/shouldn't know where the air goes.
> 
> Not knowing where you live or your air needs, you may not really need to address the humidity problems. Hook it up and enjoy it!


Ya there's two inlet ports in the top of the tank.  One for each of the two pumps.  Each inlet port has a solenoid valve on it with a line coming from the bleed off valve on the corresponding pump.  That I suppose is to cut off the tank from the pumps when the pressure switch cuts off and the bleed off valves lets the pressure off the pumps as a way of making the next startup easier on the motors.  

I think you're right, I can definitely build one a lot cheaper.     The factory version with a cooler actually has two coolers, one for each pump.   If I build one my idea would be to tee the two pumps into one cooler, then from the cooler via a water trap into one of the tank inlets and just plug the other inlet.   I could keep the solenoid valves on the lines to the tee or just use one of the solenoid valves after the cooler and before the tank.  Just a question of which is better, keeping the cooler under pressure or bleeding off the pressure from it as well as the pumps.   I'm not sure if there's a meaningful difference.

I live in Arizona at 5000' elevation so it's reasonably dry here but we do get some humidity during monsoon season.   My use, for now, is pretty low on air.  Usually just blowing off chips, running a fog buster, etc.   I am probably going to live with it a bit before I decide what to do.


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## MtnBiker (Sep 19, 2021)

diamond said:


> Ya there's two inlet ports in the top of the tank.  One for each of the two pumps.  Each inlet port has a solenoid valve on it with a line coming from the bleed off valve on the corresponding pump.  That I suppose is to cut off the tank from the pumps when the pressure switch cuts off and the bleed off valves lets the pressure off the pumps as a way of making the next startup easier on the motors.
> 
> I think you're right, I can definitely build one a lot cheaper.     The factory version with a cooler actually has two coolers, one for each pump.   If I build one my idea would be to tee the two pumps into one cooler, then from the cooler via a water trap into one of the tank inlets and just plug the other inlet.   I could keep the solenoid valves on the lines to the tee or just use one of the solenoid valves after the cooler and before the tank.  Just a question of which is better, keeping the cooler under pressure or bleeding off the pressure from it as well as the pumps.   I'm not sure if there's a meaningful difference.
> 
> I live in Arizona at 5000' elevation so it's reasonably dry here but we do get some humidity during monsoon season.   My use, for now, is pretty low on air.  Usually just blowing off chips, running a fog buster, etc.   I am probably going to live with it a bit before I decide what to do.


Water in air lines is a problem for painting and plasma cutting. Maybe extended use of air tools if you don't have an in-line oiler. Your Fog Buster and blow gun won't care a wit. Balance the brain damage with real need.


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