Will a Bigger Compressor Make me Happy?

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SteveHGraham
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Will a Bigger Compressor Make me Happy?

Post by SteveHGraham »

Tomorrow my shop will be upgraded electrically so I can get things running again. Right now, I don't have my big lathe, my mill, or my big compressor. They're all in South Florida, and I will have to pay to move them here.

I'm thinking of selling the compressor. It's a 5-HP Curtis (actually a Fu Sheng). When I got it, it was a dream come true, but it seems like it poops out with buffers and the DA sander. It's rated at 17.3 CFM. The next step up is about 7 CFM more. I hate to pay to move a compressor and then sell it.

I wonder what others here are doing with their compressors. Is my experience typical? I'm wondering if maybe I'm not getting all the performance I should. I use 1/2" hose. I thought I had the right plumbing on the way out of it.

I want to make sure of two things: 1) I need a bigger compressor to do what I want, and 2) the bigger compressor will do what I want. I don't want to buy a 7-HP compressor and still have to wait for it to catch up with my tools.

I was thinking I'd get another Curtis or a Quincy, but Emax sells a compressor which--according to them--pumps out over 30 CFM. I don't see how that's possible. You would think that if a 7-HP machine could do that, every company would have one that pumps that much.

Emax is really Eaton. They were underdogs a few years back. Now Home Depot sells Emax. I bought one of their portables a long time ago. It leaks oil, and the hose between the pump and tank blew out.

They claim their stuff is American, but it has a great deal of Chinese in it. I don't know if it matters any more. FS-Curtis really means "Fu Sheng Curtis," and I'll bet Quincy is now Chinese, too. It's really Qing Tzu. Probably.

I have grave doubts about the company, but 30 CFM sounds really good. They have a long warranty, but one wonders how useful it really is. Are they going to send a mechanic to my farm, or do I have to ship them the compressor, or what?

Anyway, I am interested in whatever useful input people have.
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

If I recall correctly, you have the same compressor that I have. Curtis 5 HP 80 gal with the E57(?) compressor?

If so, that already has the big pump on it, but just the smaller 5HP motor. The only difference between and the higher capacity is the motor HP, so very easy upgrade. I've considered doing just that, but it's been sufficient to my needs such that I just don't have it as a high priority. Plus the only likely motors I have on hand are 3 ph, and I like that the compressor runs without the converter running.

Regarding most compressor claims, I would take that with a loader bucket of salt. Again, talking what I think I know and above my pay grade, CFM at pressure is, baring efficiency issues, strictly a function of HP. Like the supposed 5 HP motors @ less than 10 amps on 220V, I just ain't buyin' that 30 CFM off 7 hp, unless maybe it's at 2 psi or something.
Russ
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SteveHGraham
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Re: Will a Bigger Compressor Make me Happy?

Post by SteveHGraham »

I think that's the same compressor. Curtis Challenge Air.

I thought it was a bad idea to speed the pumps up. I don't know where I'd get info on the right pulleys, either. I guess the information must be out there somewhere.

New pumps are not inexpensive. I looked into that. Cheaper than a new compressor, however. I think it could be done for $1700 if I found a motor for a good price.
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SteveHGraham
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Re: Will a Bigger Compressor Make me Happy?

Post by SteveHGraham »

It looks like I don't have the same compressor after all. Mine has more than one cylinder.
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

Mine is a 2 stage intercooled, so 2 pistons with a heat exchanger between stages. And you don't upgrade the compressor by speeding it up. The compressor design has a specific working range for efficiency. You upgrade by adding HP within the limits of the pump. And I seem to recall seeing that the E57 is used up to 10 HP, though again from memory, Curtis didn't offer more than 7 (7.5?) HP on this series of compressors.
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

I decided to take a moment to look it up. Curtis site seems to no longer make it easy to find ratings and such...

https://krugeair.com/fs-curtis-reciproc ... ompressor/

Mine (yours?) is the vertical on this page. Curtis 5E2VT8-A2 is what I have. According to them, it looks like it's rated up to 7.5 HP before you need a different compressor. I still think I saw or was told somewhere that it was good up to 10HP, but that may be slipping into its safety margin
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

I found this on another page. Nobody called him on it, but it is the internet...

21.2 @ 100 psi
20.3 @ 175 psi

It runs my big blast cabinet just fine. I don't just lay on it for hours, but that same cabinet literally took ALL the wind out of my previous "7.5 chinese HP" 60 gal in just a couple of minutes.

Edit: Never mind. He was talking about 5HP, but looks like he's quoting the 7.5 HP flow rates. If yours has the E50 pump (as seems indicated by your flow rate?), then yeah, you are at the limit.
Last edited by BadDog on Mon Sep 23, 2019 6:52 pm, edited 1 time in total.
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warmstrong1955
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Re: Will a Bigger Compressor Make me Happy?

Post by warmstrong1955 »

I have an Ingersoll Rand 2475 T30. It was built with a gas burner, and I converted to electric.
Rated at 24 CFM @ 175 PSI.
Whatever you look at, check on the CFM rating @ pressure. Pressure goes up, CFM will go down.
2 cylinders, I would suspect a two stage. That's the way to go. They have better higher pressure CFM capabilities than single stage. 90 PSI is about the same as 175 PSI.
I have nothing but 3/8" hoses, other than one, for my 3/4" Impact. For everything else, 3/8" is plenty adequate. The 3/4" impact will run OK, for most stuff, with a 3/8" hose....but when it gets to the really tough stuff, like lugnuts on a loader, the 1/2" helps, noticeably.
I have no tools that my compressor will not keep up with. 4-1/2" grinder, 9" sander, my blast cabinet....nothing. It laughs at things like die grinders. The ol' T30 will kick in & out when I run any, regardless.
That's the goal. Nothing worse than sitting there waiting for air pressure to build back up again.

You may take a look at the compressor you have. Like Russ says, many can easily be bumped up to a higher CFM, by changing the motor from....say.... 5 to 7-1/2 HP, with a new pulley so they spin faster.
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

IIRC, when I was considering upgrading my Curtis to 7.5 HP, all that was required (according to Curtis tech) was to fit the pulley hub to the larger shaft. No speed change. But that was a couple years back now, so my memory may be fooling me. Perhaps that was an intermediate but wouldn't produced the full rated cfm vs Curtis OEM equipped? But I thought I recalled that the motor was the only difference. I also seem to recall him telling me I didn't want to spin it any faster due to heat and premature pump failure, but maybe that was at their 7.5 speeds? I also seem to remember an online manual that listed performance characteristics of that pump, including rpm ranges and impact. If interested, probably best to do what I did back then, and contact Curtis tech before investing more than a consideration...

Speaking of lines, tangent off the compressor topic, the couplers make a HUGE difference to max flow (as does length). My 3/8 lines are all Milton V series, which have much better flow for the size than most anything else. My 1/2" lines, used for 3/4 impact and blast cabinet use Milton G connectors.
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warmstrong1955
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Re: Will a Bigger Compressor Make me Happy?

Post by warmstrong1955 »

Most underground mines, use tru-flate for 3/8", which I think is a T style Milton. They held up better, which is saying something in a mine.
1/2" couplers, I too, have G series. Got a coffee can full of other styles, from other places I have worked. Seems the 3/8" sise, for 1/4 & 3/8 hose, was the only standard.
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Re: Will a Bigger Compressor Make me Happy?

Post by Jawn »

SteveHGraham wrote: Mon Sep 23, 2019 5:56 pmI'll bet Quincy is now Chinese, too. It's really Qing Tzu. Probably.
Last time I eyeballed a Quincy at Northern Tool it had a US made motor and I think the pump was of US origin too. YMMV. Not the case with my IR... I think the motor is Mexican and the pump is Chinese.
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BadDog
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Re: Will a Bigger Compressor Make me Happy?

Post by BadDog »

I thought I remembered mine was cast with "Made in USA", but just took a look, and it appears either I am mistaken, or it's on the side near the wall. I didn't care enough to climb over to see...

Yeah, I know what you mean. In a previous life, I owned various vehicle related businesses and hobby stuff. Back then, at the first of it, I was using mostly M style, and standardized on those. The T style is what I've heard called "automotive", which are better than M, but that's not what I started with. As such, I've also got a bin full of all sorts of male and female connectors pretty much covering the Milton lines and a few others I don't remember the names of.

When I bought my current property/shop, previously a professional CNC job shop, it was plumbed with one of those unknown others, that expanded my bin of useless connectors. So I just made up short drop lines and hung them about the shop along the copper distribution lines. There is at least 1 drop in range of all machine tools, and the garage doors, plus a 50' Cox real near the main bay door. And I've got a manifold with multiple ball valves off the tank that lets me isolate from the shop distribution, run full pressure, or regulate the entire distribution systems, and/or drop straight off to 1/2" (for blast cabinet). All controlled by a ball valve. One drop has its own regulator and duplex filter for painting. Another near the main door has an oiler with dedicated hose used for nothing else. I don't remember the last time I used that, really not much use unless a full time mechanic, but it was left in the shop, so...

That's also the time I decided to transition all my 3/8 females to V because I sometimes wanted to have higher flow at any given drop. And the M fitting also connect to V fittings. So, all my old assorted M male fittings got distributed to all my low consumption tools. And all my "extension" lines and high consumption tools got spanking new V fittings. The Milton V fittings are also easier to connect. Nice thing is, I made an adapter from V to G, and even the 3/4" impact runs fine off a single 3/8 drop line, though I drag out the 1/2" if I have to make a longer run.
Last edited by BadDog on Mon Sep 23, 2019 7:34 pm, edited 3 times in total.
Russ
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