deciding between a couple compressors

[canuckian]

looking at 7.5 hp 120 gal Quincy QR and QP compressors. Most other things being similar (ACFM, pressure, tank size), the RPM on the QR is 786but the QP says 1026 RPM. would 250 RPM make that much of a difference in how loud the unit runs? The QR is obviously the better unit overall but trying to decide if the lower RPM and slightly higher ACFM is worth it if the unit is 50% more expensive.

thanks

 

[Major Ramifications]

Some links would help.

 

[jahcure]

Depends on your intended use ? What's the duty cycle you intend on having on a average work day ?

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[canuckian]

Couldn't find links for those exact models but here's a link to the QR brochure. model I'm looking at is F340

QR- www.chreed.com/quincy/pdf_files/reciprocatingQR25Brochure.pdf

Tried to link the pdf for the QP but it comes up broken. here's the description the sales rep sent me with some specs.

"Quincy Compressor Model QP7.5-7.5-120H Simplex Reciprocating Air Compressor rated at 22.6 ACFM at 175 PSIG. The Tank Mount Unit is built on a 120 gallon tank and powered by a 7.5 hp, 230/1/60, ODP, standard efficiency motor with the compressor operating at 1026 rpm."

 

[canuckian]

Depends on your intended use ? What's the duty cycle you intend on having on a average work day ?

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inteded use is nothing real special. blasting, sanders, grinders and other regular air tools. Duty cycle on both units is 100% but I'm not a pro shop so that's not really an issue anyways. I'm getting one or the other but just looking for peoples' opinions and experience of lower rpm compressors and if it's worth the money to have a quieter unit and a bit more cfm. I have a 25 gal Husky at the moment and though it's an oiled unit, it's really loud and runs continuously if I'm using air hungry tools, if it can keep up at all.

 

[zkling]

Don't take this the wrong way but judging from your other posts, to me you seem like a person that really appreciates quality and are willing to pay for it. In that case go with the QR series.

Yes the sound will be a noticeable difference, but not night and day. One thing about the QR series though with the unloaders they make a distinctive sound, both at start up and shut down.

Just throwing this out there, have you checked the used route?

 

[canuckian]

Not taken the wrong way at all. You're correct I do appreciate quality. I believe in the buy once cry once philosophy as long as I can comfortably afford it. How much something costs factors into the decision the same as it would anything else or for anyone else.
I have no first hand knowledge of larger Quincy compressors so I'm depending on those that do to help me make a decision. I'm sure either of the 2 will serve me well but I'm at a stage of my life where if spending a bit more means the difference between almost what I wanted and exactly what I wanted, then I'll spend the extra money. If the less expensive one will meet or exceed all my expectations and needs, then I'll save a few dollars and still have the tool I need. Thanks for the pointer on the unloader. Had never noticed one sounding much diferent than another.
As for the used market, the only thing that ever comes up here (and I've been checking!) is pancake compressors and old beaten junk. A compressor is honestly something that I'd rather buy new or close to new. A metal cylinder holding 175 psi+ sitting in the middle of my shop is something i'd prefer to know the history of.

 

[bsaint]

I don't know where this slower pump speeds = longer life got stuck in everyone's head.

I guess many people doubt the ability of engineers to design a simple air compressor. Its not the pump speed that reduces life. Its the lack of maintenance and poor build quality. A good example of a quality unit is the high speed old Worthington pumps. Their motor and pump pulleys are almost equal size. But they last forever and they are still out there pumping away. They have a tiny stroke keeping the mean piston speed somewhere around a slower compressor. Common wear items like bearings and the like, when properly lubricated, will last just as long at 700 rpm as 1200 rpm. Think about how long bearings in an engine last at average speeds of 2 - 3k rpms with people neglecting them and operating at way hotter temps.

So when it really comes down to it, just buy the one with better build quality despite the pump speed.

 

[scw1991]

as zkling has stated, you obviously recognize quality. I think the QP would be more than suitable for your application and outlive you and your kids (if you have any). These like most industrial rated compressors have a 100% duty cycle. They are meant to run non-stop 24/7/365 and be industrial work-horses. If I had a "critical" application where I needed a 100% duty cycle compressor, I'd opt for the QR if money was no object.

What's nice is that both these models have a forced oil lubrication system. That by itself sets these compressors far apart from the conventional splash oil lubrication system.

 

[zkling]

Maybe try finding a good used 325pump and piece a compressor together. That pump has been around for a long time. I don't even want to know what a brand new 340 setup costs from quincy. After I reread your posts, going from your current 25gal to the 120gal 340 QR series is a huge change. Maybe consider a smaller QR pump to save a few bucks.

 

[unashamedlaborer]

If you can make it happen $$$ wise the QR series is definitely the way to go. That's basically what I have in a 5hp model 216. The major Benefit is true unloaded starting, there are many differences between the two designs though. This is the major. It frees up a lot of potential if you want to run it stop start or continuous load unload, the fact that it will not load without sufficient oil pressure means it won't destroy itself if it runs low on oil, I could go on and on about the differences but long story short the QR series is the real deal, the QP series is great on the bottom end but is lacking a hydraulic unloader assembly (any unloader for that matter), there is no easily serviceable disc valves like the QR. Also the info you posted on the QP said it comes with an ODP motor. I'd bet the QR comes with a TEFC motor which is a big step in the right direction if you are going to keep it in a dirty/wet environment.

 

[canuckian]

Thanks for all the advice so far. The compressor will be in a climate controlled shop so no worries about it getting wet. The more I read up on the QR and QP compressors the more I see that there are some pretty big differences between the 2. The QP would likely do all I need it to and never cause me a lick of problems but, I think I'll see what kind of deal they can cut me on the QR. If they can't come down to what I can pay, then I'll look a little harder at the QP or maybe the 5 hp QR 325. the 325 has a fair bit lower ACFM rating than the 7.5 hp one but I'm sure it can run a blast cabinet, sanders and grinders no problem at all. or can it?

 

[zkling]

Correct me if I am wrong, but I assume you are a single man operation. Meaning that you will only be drawing from one air source at a time? Very seldom two if you have say a plasma system or a VMC? If that is the case I highly doubt you could wear out a 325 in your lifetime. The 325s and or a multiple of them have been running body and tire shops for many a years. Unless you have a large orifice media gun I think it would be all you need and then some. But talk to quincy they will help you to determine the compressor that is right for you based on expected air needed and duty cycle. There is a margin you want to be in, between running the pump long enough to drive off moisture and too long where wear is a concern.

 

[unashamedlaborer]

The standard rule for industrial/commercial compressors is 4cfm per hp. So you would have to know what kind of cfm you are going to need but unless you are blasting for a long time continuously than a good sized receiver will cover a lot. Also you can fit a pilot valve to the qr series so that you can set it to load and unload in a very short pressure band say 115/120 if you are blasting

 

[canuckian]

yes, I'm a one man show for the most part. No plasma or anything yet and rarely is there more than one air tool running at once, if ever.

The 5 hp 120 gal QR is rated at 17.6 ACFM at 175 PSI. I admittedly don't know a lot about ACFM ratings and how they're affected by pressure settings so as long as the 5 hp will run a blast cabinet and some body tools, I'll likely be good with that one. I have a tendency for overkill so that's why I was looking at the 7.5 hp. If I won't benefit from the extra ACFM that it will provide, then I won't bother dropping the extra coin on it.

 

[javajaws]

I spent a lot of time the last month choosing a compressor. Similar needs to yours, but no blast cabinet.

I think for your needs you don't really need pressure lubrication. If you have the money to spend on it, by all means go ahead. But I just don't think its necessary.

On a disc valve compressor that won't see heavy daily use I would make sure it has a check valve between the tank and pump or you might get leaks from the disc valves due to the higher possibility of them rusting (thus requiring more frequent maintenance). I'm not sure if current Quincy's include one by default - something to check into.

I personally found better value in Champion and Saylor-Beall (I was looking at splash lube models). I wouldn't count them out of the running just yet unless you just happen to have a local Quincy dealer you want to do business with.

 

[canuckian]

the Quincy dealer, which is about an hour from me is about the only local dealer I've found for any brand of compressors other than ones you'd find in a big box store. Not discrediting those, I'm just in the market for something a little higher in the spectrum.

Ill definitely ask the dealer about the check valve. thanks for that info.

 

[canuckian]

well, I just put the order in this morning. Dealer emailed me to let me know he could save me the freight costs somehow(piggybacking a larger order as far as I could tell). That knocked $700+ off so I figured now was the time. I decided on the 5 hp QR325 with a 120 gal tank. Not 20 min later, I get another email informaing me that the 120 gal with a 5hp motor wasn't CSA certified so he couldn't import it and to get a 120 gal tank I'd have to step up to a 10 hp. That's not gonna happen. He then sent me a revised (cheaper) quote on an 80 gal QR325 so I went ahead with that. Should be here in about 3 weeks, just in time for the shop to be completed. Safe to say I'm a little excited!

 

[unashamedlaborer]

well, I just put the order in this morning. Dealer emailed me to let me know he could save me the freight costs somehow(piggybacking a larger order as far as I could tell). That knocked $700+ off so I figured now was the time. I decided on the 5 hp QR325 with a 120 gal tank. Not 20 min later, I get another email informaing me that the 120 gal with a 5hp motor wasn't CSA certified so he couldn't import it and to get a 120 gal tank I'd have to step up to a 10 hp. That's not gonna happen. He then sent me a revised (cheaper) quote on an 80 gal QR325 so I went ahead with that. Should be here in about 3 weeks, just in time for the shop to be completed. Safe to say I'm a little excited!

Good man!!! You will not be disappointed. If you really need the extra capacity then just get an additional receiver tank. I don't know what the laws are like where you are but here a permit to operate a pressure vessel isn't that expensive and tanks are a dime a dozen and cheap to free.

 

[zkling]

80 gal QR325 so I went ahead with that.

Yea, that will fill up a tire or two. Congrats, I'm sure in a few...dozen years down the road you will be happy you went with the ultimate.

 

[canuckian]

Good man!!! You will not be disappointed. If you really need the extra capacity then just get an additional receiver tank. I don't know what the laws are like where you are but here a permit to operate a pressure vessel isn't that expensive and tanks are a dime a dozen and cheap to free.

looking into the extra tank now. AFAIK there's no extra permit to use one here. Only issue for me will be space as I had sized he area that the compressor was to go for a single 120 gal horizontal tank. Not sure there's room for an extra tank after the 80 hal horizontal one slides in. Maybe on the wall above it. Not too worried as I'll likely be fine with the 80 gal take on its own.

Yea, that will fill up a tire or two. Congrats, I'm sure in a few...dozen years down the road you will be happy you went with the ultimate.

thanks! yeah with all that I've read on the QR series I figured I couldn't go wrong. The intent that this was to be the last compressor I'd ever have to buy and I think it'll satisfy that requirement for sure.

now shopping for an air line setup.Liking the looks of the aluminum stuff from RapidAir....

 

[78Bird]

I'd use the 80 for a bit, as a 1 man shop that is a beast of a compressor, unless you do some serious blasting that thing won't break a sweat.

More tank wouldn't gain you much in useability... just make it run a little longer, a little less often.

Spend the $ on setting up a good air system to deliver the air to your work area and keep it nice and dry.

Edit: If you can sweat copper you can custom build a system for likely a good bit cheaper than the rapid-air (though i admit the RA is super easy assembly)

 

[canuckian]

I'd use the 80 for a bit, as a 1 man shop that is a beast of a compressor, unless you do some serious blasting that thing won't break a sweat.

More tank wouldn't gain you much in useability... just make it run a little longer, a little less often.

Spend the $ on setting up a good air system to deliver the air to your work area and keep it nice and dry.

Edit: If you can sweat copper you can custom build a system for likely a good bit cheaper than the rapid-air (though i admit the RA is super easy assembly)

Was looking at using copper but honestly I'm not great at sweating copper and I like the ease of installation and adaptability of the rapid air stuff. The only real drawback to it for me is that there's no local supplier that I'm aware of for it so it'll likely have to be shipped to me. The place I ordered the compressor from does industrial air systems. I may have to see what they use and if it's similar, I may just get something through them if it's cost effective.

 

[canuckian]

Picked up the compressor yesterday. Good lord this thing is a beast! They loaded it into my truck with a forklift and all the while I had no clue how I was going to get the damn thing out. Im sure i could have gotten enough guys to get it out of there but theres always the danger of it falling on someone with it being so top heavy and awkward. Turns out the guy that built our house and shop has a boom truck coming tomorrow with some siding for the house he's building across the street so he's going to get the operator to slip across the street and drop the compressor onto some dollies in the shop. Saves me a few $$ and a bad back so I'm happy! Working on a deal for an aluminum piping system with the people I got the compressor from. He's saving me the freight (same deal as compressor, piggybacking a stock order) so I should be able to get it for a bit less than rapidairs offerings.
Anyways, enough of my rambling, here's a couple pics....

Also picked up a dryer

 

[unashamedlaborer]

She's a beauty!

 

[metal4130]

So nice! Do they make the QR-325 in a vertical tank model?

 

[canuckian]

So nice! Do they make the QR-325 in a vertical tank model?

Yes they make a vertical version. That was what I was originally looking at but the horizontal version fits better in the space I have planned for it.