just bought my first "real" compressor - is it too big?

[sberry]

Actually we are or might be talking to a guy that should get past this by going to the store and scoring a new Champ comp, hook the wire and a hose to it, dump some oil in and dribe it like it was stolen. Adjust the belt in a couple years and change the oil once and run it till its broke,,, at which point if it happens will be beyond depreciated and have paid its way by multiples.

 

[MrSurly]

A tip for the O.P....
It ain't just Sberry, it's many others and I'll add to them. There are simple reasons that most of the opinions are to sell this beast and buy the compressor you actually need. They have been stated well. The three phase part of the equation is not even the most important part. That distinction goes to the 15HP pump. That beast *requires*HP to run. Sure, it could be "re-geared" to turn much slower on fewer horses, but then you've lost the CFM promised on the label, so whats the point?
Clean it up, sell it (for a profit!) and then buy a single-phase 5HP quality unit and quit creating new non-productive tasks where they needn't be.

*I am especially qualified to address this because I am BaaaaaaaaaaD about sidetracking myself with just exactly this kind of activity*

 

[bczygan]

I've done the cheap old Speedaire compressor renovation.

Got a 60Gal horizontal tank, 5HP 3Ph for $100.

Lucky to find a NOS single phase 5HP motor for $200.

Bought a single phase motor starter for $120.

New check valve. Misc, hookup things and lots of cleaning.

So for $500 and a bunch of work, I have an old compressor and tank with a NOS motor and new motor starter.

I was pinching pennies. And this is a nice slow speed compressor, chuga, chuga, chuga!

For those that are willing to spend more for all new equipment and a warranty, the options are there.

For a 25HP one I would look at the specs on the pump, to see the smallest motor that would push it.

Bill

 

[md21722]

That is a Champion RV-30A pump rated for 7.5, 10 or 15 HP at 575, 740, or 1045 RPM. If you are into changing the motor and magnetic starter I'd keep it. Even the tank itself is nice to have for extra air storage. I would be cautious of the condition and number of hours on it before putting money into it.

 

[sberry]

Its good to know what pump it is,, 7.5 makes it a bit more practical. I wasnt sure ehat was on it, could have been 15/20 hp too.

 

[gnxtc2]

Just an idea, consult with an electrician. Your electric utility company might give you 3 phase power for free since you have the requirements now. You'll have to change your service to 3 phase.

From the sound of it, you might be able to get away with a 200A, 120/208v service. Then you won't have any restrictions of getting any type of equipment you want.

Billy T.
[email protected]

 

[American Locomotive]

That is a Champion RV-30A pump rated for 7.5, 10 or 15 HP at 575, 740, or 1045 RPM. If you are into changing the motor and magnetic starter I'd keep it. Even the tank itself is nice to have for extra air storage. I would be cautious of the condition and number of hours on it before putting money into it.

Well there we go. Get a 7.5HP single phase motor, put a smaller pulley on it, and the OP is all set.

 

[CamaroMan]

Well we plugged it in yesterday and it ran perfectly -

So in summary the 120 tank with a smaller motor/pump will give me alot more reserve but take longer to fill? The motor wont strain more just cos of the bigger tank will it? just the longer run time really?

 

[Packard V8]

Well we plugged it in yesterday and it ran perfectly -

So in summary the 120 tank with a smaller motor/pump will give me alot more reserve but take longer to fill? The motor wont strain more just cos of the bigger tank will it? just the longer run time really?

Congrats.

Yes, the 120-gallon tank will give more reserve.

Yes, running the pump at the lower RPM specified for the lower horsepower motor will take longer to fill the 120 gallons.

No, a longer run time to fill a larger tank can be balanced against less frequent cycling. A smaller tank pulls down sooner and has to start the motor more often to refill. Starting under load is the hardest work the motor does.

jack vines

 

[CamaroMan]

tx jack - what I meant was switching out the pump and motor (matched set) to a smaller setup, 5hp maybe - ill sell off the 15hp motor and pump in that case. If i get a buyer ill probably look for a 80 gallon ready to go..

 

[md21722]

Well we plugged it in yesterday and it ran perfectly -

So in summary the 120 tank with a smaller motor/pump will give me alot more reserve but take longer to fill? The motor wont strain more just cos of the bigger tank will it? just the longer run time really?

Depending on work load, there will be less strain because there are fewer start-stop cycles on the motor, but the cycles will be longer. Also, running that pump at 7.5 HP would be less strain on it too, because it will only be turning 575 RPM.

I would keep the pump, change out the motor to a single phase 7.5 HP, change the magnetic starter, and change the motor sheave to the appropriate diameter and run it!

 

[Bert_]

Depending on work load, there will be less strain because there are fewer start-stop cycles on the motor, but the cycles will be longer. Also, running that pump at 7.5 HP would be less strain on it too, because it will only be turning 575 RPM.

I would keep the pump, change out the motor to a single phase 7.5 HP, change the magnetic starter, and change the motor sheave to the appropriate diameter and run it!

The starter that he has might be fine.

If it was wired for 230V 3Ø then the starter will work for a 7.5hp on 1Ø since both would require a size 2 starter. Might need to change the heaters or if the turn the dial if the overload is adjustable.

Of course non of that applies if it was wired for 460V.

 

[930dreamer]

X2 on keeping the pump.

 

[Lonstar]

OP - research the compressor pump and figure out what size single phase motor it'll take to spin it (amp draw is key, get it wrong and you'll burn up a motor), and what else is needed to make it run. Then make up your mind.

I'm going through this exact process. If you're mechanically inclined and have a brain you'll figure it out. Just have to research the **** out of it. There are some smart guys answering this post, need to figure out who they are and read what they say, others are just people trying to help but really don't know. Again, up to you to figure out. Most importantly. YOU need to research it and understand the questions your asking, don't rely on the opinions of strangers. When you understand it better you can come back to this post and know which posts matter and which don't.

I can offer this much - if 7.5 hp will do, $650 for motor. If 10 hp, $1000 for motor. Get 1750 rpm, not 3450 rpm. Magnetic starter - $150 (you'll need it). A lot more, but this is a start.

If more that 10 hp is needed....might want to bail. You won't know until you research the compressor pump and find out what it'll take to spin it at the appropriate speed, and the hp/amps needed to achieve that.

 

[dirtydogintex]

$200 for a 120 gal @ 200 psi code tank is a you **** steal round these parts.
The motor, pump and starter are gravy esp if you expand and move to a larger facility with 3 ph power.

For now buy a 1ph air compressor and use the 120 gal tank for a receiver drier and not look back.... other than to periodically drain both tanks.

 

[sberry]

With a bigger tank you can kick on at a bit higher pressure without short cycling too. Bigger tanks give it longer span with smaller pumps to give the operator more range to time cycles too. In my own case I have near 5 minutes to resume use if I stop at kick on before it turns off, very forgiving to be able to run pump steady. A secondary sheave is an added cost to downsize, this isnt always a deal to find. In California it could sit under cover outside, in some cases where building cost is hi, use modest this could take up 600$ of extra real estate over a vert.

 

[Citation]

OP,
I don't know where you live but I figured it was worth throwing out a "what does Craigslist have". Since I don't know where you live I decided you live in Dayton, OH. Here are three compressors I found that are probably well suited to your needs.

https://dayton.craigslist.org/tls/d/husky-80-gallon-air-compressor/6744959320.html
https://cincinnati.craigslist.org/tls/d/air-compressor/6761847268.html
https://columbus.craigslist.org/mat/d/air-compressor-80-gal-65-hp/6762088120.html

All are lower end 80 gallon, 2 stage units that were probably $1300-1800 new. My dad has the Husky. We got it for free from a friend who was trying to clear junk out of the shop he moved into. It needed a small bit of work but I'll emphasize small.

Anyway, that 4hp Husky works with my dad's sand blaster and can keep up with the limited painting he still does. Years back he had a true 5 hp compressor that kept up with car painting and the sand blaster without any delay. I think 4hp would result in the occasional slow down.

Anyway, all of these compressors are under $800 so probably less than you will spend to get your new monster up and running. They are also all vertical tanks which is a nice space saver.

Here's my suggestion. You are probably, even when running this thing at just 7.5hp, way overkilling your needs. I would try to figure out how much you can sell that monster for. It's possible you could get over $1k (3ph is a bit hard as most companies will just by new or from a dealer, while small time companies/DIY types are more likely to need single phase. But if you can get $1k+ for your compressor you have enough to buy a used low end 80 gallon. Net result you would have traded your way to a free compressor vs $800+ to make that one work for you.

You got a heck of a deal but this is probably nearly double what you need.

 

[sberry]

Yes, you can sand and paint on 5 autobody very comfortable, 4 is margial. Can be done 3 but you got to be thrifty and some extra tank helps.

 

[md21722]

Since this compressor was commonly sold as a 10 HP or 15 HP unit, and 7.5 HP motors typically use the same frame size as a 10HP, you should not need to adapt much here:

7.5 HP is commonly sold as a 215T frame $614.95:

https://www.ebay.com/itm/L1510T-7-5...?epid=535280792&hash=item3cf5f788fc:rk:1:pf:0

Magnetic starter $138.70:

https://www.ebay.com/itm/SQUARE-D-M...h=item2c6a912a61:g:mkMAAOSwns1a62n1:rk:3:pf:0

If the pump has a 22-1/2" flywheel, to get 575 RPM from a 1750 RPM motor use 7.4" sheave $44.99 :

https://www.ebay.com/itm/TB-WOODS-7...xbGa4D:sc:USPSPriority!80918!US!-1:rk:19:pf:0

(575/1750*22.5) = 7.4"

and bushing for 215T frame (1-3/8" shaft diameter, for 215T frame) $25.99:

https://www.ebay.com/itm/TB-WOODS-S...h=item4b532aa3e5:g:t7IAAOSwkfxb0k~M:rk:7:pf:0

Check all part numbers before ordering.

 

[CamaroMan]

good info chaps. I live in California - i thought the pump had to be run on a matching size motor.

My buddy rebuilds these motors he shd be able to help big time ito amps/motors etc..

Here is a pic of the starter - fy its currently wired for 208 3 phase - we tested it / runs perfect.

so would a 5hp/7.5hp with a smaller pulley/sheave run this pump, just slower? and it wd be ok? I was told running a larger pump with smaller motor would burn out the motor?

 

[CamaroMan]

I could probably find a 220 5hp/7.5hp motor alone for $75 here. Guy i know has a room full of them - take offs.. ill be running htis probably off a 50a 2 pole breaker I have on the panel..

 

[Citation]

Based on what someone else said this pump operates with between 7.5 and 15hp. Your can't go less than 7.5. With less hp you have to turn the pump slower or you will overload the motor. If you go too slow you don't move enough oil in the crank. That's why you have a minimum hp. It's really the minimum speed for the pump's lubrication system to work. So long as you spin the pump at the minimum 5xx rpm the pump will be fine and like you said, it will just pump less air. I suspect you will still be over 20 cfm @ 90 psi.

 

[md21722]

so would a 5hp/7.5hp with a smaller pulley/sheave run this pump, just slower? and it wd be ok? I was told running a larger pump with smaller motor would burn out the motor?

I posted the specs for the pump earlier. 7.5 HP yes. 5 HP no.

As long as you are running it within specs there will be no issues.

A 7.5 HP motor by code requires a 50A circuit using #8 THHN (in conduit) or #6 NM-b (Romex).

 

[md21722]

Based on what someone else said this pump operates with between 7.5 and 15hp. Your can't go less than 7.5. With less hp you have to turn the pump slower or you will overload the motor. If you go too slow you don't move enough oil in the crank. That's why you have a minimum hp. It's really the minimum speed for the pump's lubrication system to work. So long as you spin the pump at the minimum 5xx rpm the pump will be fine and like you said, it will just pump less air. I suspect you will still be over 20 cfm @ 90 psi.

Correct on all points. 7.5 HP is about 26 CFM.

 

[CamaroMan]

ok thanks!

 

[Lonstar]

I could probably find a 220 5hp/7.5hp motor alone for $75 here. Guy i know has a room full of them - take offs.. ill be running htis probably off a 50a 2 pole breaker I have on the panel..

I'll take one of those 7.5 HP motors for $75!

 

[dirtydogintex]

Both down here would be Xmas come early!!