Which compressor?

Ok, after checking eBay and Craigslist and some other sources, I've
decided I'd rather get a new compressor that is delivered to my door (or
in the case of Grizzly Freight, my driveway). So given that I need about
20 CFM @ 100psi, and trying to save a buck, is there any reason to NOT
go for this Porter Cable compressor:
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as opposed to this Campbell Hausfeld compressor:
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The PC is about $160 less delivered.
Reply to
Todd Rich
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You gets what you pays for with this machine.
If you'd like one that runs quiet and lasts forever:
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I bought two el-cheapos first. Would have been better to buy the good one like I finally did the third time.
Karl
Reply to
Karl Townsend
Have you ever stood next to a cheap compressor running? They're LOUD! And they smell HOT. I once owned a DeVilbiss "6.5hp" vertical unit which looked great and spec'd out great. But when it started at night (it was in a huge basement space surrounded entirely by foundation and thick walls) it woke up my neighbors. And the damn thing wouldn't run a die grinder without running out of air, because of the phony specs. The specs are more believable these days but when you buy these import compressors and they wear out in 2 or 3 years what are you going to do?
I sold my import and bought a used Quincy 5 horse 2-stage. When it runs, it's quiet and solid sounding. It's about 30 years old and runs like a top. I paid $150 for it and put another $400 or so into upgrading the motor to single phase. Works great for everything I need it for. And yes, it will run a die grinder!
GWE
Reply to
Grant Erwin
I also had a misfortune of buying a cheap compressor first. Promptly sold it because it was unusable for the reasons that Karl and Grant mentioned. Bought a used Curtis 5 HP and have been very happy.
I would say that with about $400, and some patience, you can get yourself a very nice vertical compressor.
i
Reply to
Ignoramus7591
second the Quincy - I paid 850 for mine, 21 cfm at 160 psi, 5 hp motor, single phase, delivered
Reply to
Bill N
Unfortunately I expect it will be more than $1600 retail from what I've seen on the used prices for ones large enough. I simply can't afford any more than that for the forseeable future.
I was offered a used one when I posted an earlier compressor related question, and it was far enough away that transportation costs would have pushed me over my limit... Otherwise I would have jumped on it.
Todd
Reply to
Todd Rich
Yea, I understand. I did the same thing on many items. But, it would have been cheaper in the long run to buy the good unit the first time around. In my case, I went through three cheap tractors and tons o' repair bills before buying a John Deere orchard tractor. Now, I bought it too late in my career to come anywhere close to wearing it out.
karl
Reply to
Karl Townsend
You don't have a local supplier that can beat those prices?? Grizzly is high on their prices compared to buying local, at least in my area. Ported cable is carried by Mills Fleet Farm and Campbell Hausefeld by Tractor Supply. Home depot units are Campbell Hausefeld last I checked. Greg
Reply to
Greg O
Well, with the encouragement here, I looked again, and there was one that was use, but local to me and what I could afford.
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I'll be picking it up in 8 days. Of course since I don't have 3 phase, it looks like I'll finally be getting around to building a phase converter. Fortunatley I've found a 15 hp motor that is about as close and cheap enough that it will still be less than the Porter Cable one I was looking at.
Time to research the best way to make a rotarty phase converter.
Todd
Reply to
Todd Rich
Wow. I am rather speechless. A very impressive compressor. Do not make a phase converter, this compressor would be best run from an electronic drive, especially if it has unloader valves.
Running it will take about 70 amp from single phase under the best case (electronic drive).
What source of electric power do you have (200 amp service?)
It may not necessarily handle starting load of this compressor, unless you soft start the motor with a drive.
You really should plan carefully as to how you wire this very large unit.
I am not saying that I know the above for sure, but you should research it.
i
Reply to
Ignoramus8571
(snip)
Electronic drive as in inverter/variable frequency drive? Why is it it better than a phase converter. I was under the impression from articles I've read here that a balance rotary phase converter was the next best thing to having true 3 phase power. Also, every VFD I've seen requires 3 phase input for units over 3-5 HP.
200 amp service at the house, 100 amp subpanel in the garage where this is going.
I'll be researching. I'm not necessarily that up on electrical theory, but I'm pretty good at following directions.
Todd
Reply to
Todd Rich
(snip)
(snorp)
Sorry to follow up again, but I just got confirmation that I can pick up the motor in person and don't have to have it shipped. I really don't want to waste $150 for the motor, but I have to make a decision in the next few hours. Todd
Reply to
Todd Rich
Yes.
Let's see. I have a phase converter with a 10 HP idler motor (there is another idler, that starts at a different time, but that is beside the point). When it starts, it draws about 120 amps.
You would need a bigger idler than than, my guess about 25 HP idler. If it draws proportionally more current at startup, it has a need for about 120*25/10 = 300 amps. I am not sure if you can get that much from your service.
You have some size issues here, besides other issues. Other issues are that the compressor is intermittent, so your phase converter would be either spinning idly a lot, or you would need some complicated starting arrangement to start it prior to kicking in the compressor motor.
Not the case with ones I have seen (Siemens up to 60 HP)
This is a very interesting machine that you bought. Let us know how it goes.
i
Reply to
Ignoramus8571
There is a hack for this: derate the drive unit by 50%, hook up two of the three inputs to one leg of 220 and the other input to the other leg. A 30HP drive is a big one but there is a big advantage to using one: no starting surge. It's not clear that you could start it from your 200amp service without a soft start unit or an electronic motor drive.
At full load and 220 volts, over 100A. The electrical code & the motor starter would require one heckuva (technical term) feed for that baby! It would have to be fused for 120A according to the code at my reading, maybe more.
Program the motor drive to ramp up over 5-10 seconds and there's no problem. You will have to wire the pressure switch to the control input of the motor drive and bypass the starter. The motor drive will NOT work (for more than a day or so) with the compressor turning itself on and off without telling the motor drive!!!!
I did something very like this with a 4HP unit running off a single 20A breaker (240V). Worked like a charm. Remember, the motor drive MUST control the power to the compressor motor directly, with no relays or anything else in the way. A listed motor drive qualifies as a motor starter and a protective device under the electrical code, so you don't need them. You MUST connect any overheating sensor and the pressure sensor to the drive.
Hope this helps. geoff
Reply to
gwes
(snip)
I see them now...weird I didn't find them before, but then again, I wasn't looking for them before when I got my 3HP VFD.
(snip)
Well, not sure where the original article I was looking at, but it looks like I read it wrong...double checking several others I see I would need a larger motor anyway, so I'll pass on this one. Thanks for the kick to check again.
I've found at least one model of 15 HP VFD that takes single phase input. However they want $1400 for it, which I can't afford. I'll have to see if I can find a used one for less.
On the plus side, there is an electrician who is marrying into my wife's side of the family. I can see how much it would take to do a 3-Phase drop from the power company....
Reply to
Todd Rich
Agreed.
I have a 25 amp single phase 5 HP motor (Baldor). Multiplying this by (15 HP per OP's compressor) 3 gives you 75 amps. Use of a VFD and a efficient 3 phase motor could yield a bit more savings. Hence my 70 amp number.
Good question.
Yes.
The drive can be programmed to work as an overload, also.
i
Reply to
Ignoramus3531
By the way, I used to sell such drives, bnut I no longer do so, so there is no profit motive in suggesting a VFD.
What motor exactly are you talking? The possible motor for an idler? What kind?
You need a VFD rated for 30 HP three phase input. Basically you need a drive that
1) Can be run from single phase
2) Has motor FLA rating at least 150% of the FLA of your compressor's motor
As for the cost, those Siemens drives sold for $400 apiece, more or less, up to 60 HP rating. With a little bit of looking, you can find a suitable drive for a lot less than $1400. You would need to do a little bit of research.
That's great, as long as he does a little more beyond house wiring.
A lot more than the drive.
i
Reply to
Ignoramus3531
WOW, I'm GWE (green with envy) What a unit.
Iggy's right, get a VFD to run this. Set it up to accelerate slow and not go to full speed. Then this compressor will run quiet and last forever. If you're short on electric line amp size, just running it slower with the VFD will solve the problem.
Bet ya Iggy will help out with finding a suitable VFD and directions to set up.
Karl
Reply to
Karl Townsend
Me too.
Just make sure that the motor is sufficiently cooled, as its fan may not be sufficient at lower speeds. (adding an extra fan is all that is necessary, if that)
I do not have any for sale in his size (mine are all 0.5-5 HP), but I saw several on eBay that may work, for a lot less money than $1,400.
VFDs are not that expensive if you make an effort looking.
i
Reply to
Ignoramus8571

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