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advice on buying new pump for Air Compressor

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Forum topic by Jerry posted 353 days ago 1100 views 0 times favorited 22 replies Add to Favorites Watch
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Jerry

2163 posts in 2144 days


353 days ago

Well, we work our compressor hard. Our air compressor gets used more than anything in our shop. The pump has gone bad on the compressor. It is a speedaire 80 gallon 7.5 hp. A new pump through grainger is 1400.00 and just a rebuild kit for the pump is just shy of 500.00 after taxes. I am considering getting an Eaton pump that comes with a 5 year parts warranty. It would be an upgraded pump based on specs.

Here is the link:

http://www.eatoncompressor.com/catalog/item/518643/1320611.htm

does anyone have experience with eaton pumps?

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net


22 replies so far

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Shawn Masterson

1240 posts in 546 days


#1 posted 353 days ago

the ad states 10Hp you have 7.5Hp. If you feel comfortable with under powering it then by all means. It looks like a good quality old school pump.

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Jerry

2163 posts in 2144 days


#2 posted 353 days ago

Yeah, I noticed that. Not sure if running it with a 7.5 hp motor would be a major issue or not. I am going to sleep on it. We use a lot of compressed air and so I want to go with the best solution I can afford. I am going to sleep on it.

I have scanned CL but in a pinch I am forced to go new. Maybe if I put out the money (815.00) shipped, I will not have to put out anymore money for the compressor for a very long time.

I have been thinking about why the pump has gone bad. We have the compressor against the wall in the shop. The pump feels hot anytime we use it. I am wondering if having it against the wall as it is that the pulley is not generating enough through wind into the pump to help keep it cool.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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dahenley

125 posts in 690 days


#3 posted 353 days ago

naturally they are hot…. (just from the friction/compression of the air)

if your fishing around the 1000$ mark, you might just look into a whole new unit, and keep the 7.5 motor as a spare/sell it and hook your tank to the new one for 2x the volume. (which might help prevent it from running all the time. (although with 2x the volume, it might take a little longer to fill, but there is more time between filling)

i see your in the san/antonio area. in dallas/tyler east texas. there are some rotary air compressors used for 1200$ last time i looked. which would be less noise and more air faster. just something to look into.
and you could sell your old compressor and motor to help re-coop some money?

good luck!

-- David Henley

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Jerry

2163 posts in 2144 days


#4 posted 352 days ago

That is something to think about. I am going to think and sleep on it. Our biggest air hog is the dynabrades we use. We often will run 2 DA sanders at a time. We spray a lot also but that is not the huge air hog.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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TopamaxSurvivor

14587 posts in 2273 days


#5 posted 352 days ago

That is a 33% overload for the 7.5 hp motor. I would expect electrical problems next ;-(( Tripping overloads or over heating and burning up motor if they are not properly sized.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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Jerry

2163 posts in 2144 days


#6 posted 352 days ago

I have been researching this all day. No decision as of yet. I analyze things like this probably more than the average.

The air compressors sold on that web site are Puma air compressors and they have that same pump on their 7.5 hp 80 gallon compressors. The article they include with the pump gives a lot of details and in the article it does state this 10 hp pump can work with a 7.5 hp motor. I don’t think there will be any issues with the pump. If anything the pump might be an issue for the motor causing my motor to work harder with a larger pump and therefore killing off the motor prematurely. I can still go with the smaller pump which states has 26 cfm, still enough for what we do.

I am at this time a bit on the fence with options. In my research I found this exact same pump, no brand name is on the pump but for comparison sake, it is the same pump as far as I can tell. I spoke with them and they told me these pumps are mgf overseas (not a huge issue since most things are now) and advised me some dealers will choose to brand the pump and some don’t, so they do not brand the pump. They are selling the exact same pump for 650.00 with free shipping where as the site claiming it is an Eaton pump is selling it for 599.00 plus 215.00 freight charge. The Eaton pump web site claims the pump has an Eaton Mfg. warranty of 5 years on parts. The other site claims only a 1 year parts warranty. Both pumps look identical and both are built with cast iron.

The other site I found the pump on is compressorworld at http://www.compressorworld.com/10-hp-Air-Compressor-Pump-2105-p/2105.htm

I said I analyze all of my options. I looked on CL in Houston, Dallas and San Antonio. I did not find a Rotary Screw compressor inside my budget. The closest deal I found that I might be willing to entertain is a decent 80 gallon 5 hp compressor, the guy says he bought it at Snap On but stated it is not a Snap on. He told me the maker but I forget. He only wants 425.00 for the compressor. If I bought it, I could use my 7.5 hp motor on it, and tie both 80 gallon tanks together giving us 160 gallons and hope with might that the pump on that used compressor keeps up. He stated the pump is speced at 21 CFM which would handle our DA requirement. But then if the used/older pump fails, then I am back in the same boat.

We only own 2 compressors, the Speedaire and a small PC pancake compressor. This week we are building 73 doors and have sanding and spraying tasks that should take us into the beginning of next week. So my decision needs to be wise and quick.

Thanks, Jerry

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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dahenley

125 posts in 690 days


#7 posted 352 days ago

the eaton you listed is a ton of air (compared to most retail compressors)
you might be able to get the 4 stage and just upsize the 7.5 compressor pulley.

you will get less CFM, but the 7.5 will be able to handle the extra load
and if the 7.5 ever goes out… just upgrade to a 10HP pump with the right pulley and your back to 34/38CFM

-- David Henley

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Jerry

2163 posts in 2144 days


#8 posted 352 days ago

James I wish I had more experience with these things. I have not taken it apart yet. I think I will take it apart tomorrow just to be sure before I order a new pump.

But here are the symptoms: Started last week. The motor will run the pump and then the pump will get very hard to spin (like it is beginning to sieze up) and the motor begins to overwork, the big guy begins to run very rough and the breaker trips under extreme load. Honestly, I don’t get as much shop time as I would like. My wife is in the shop more than I am. She reported to me this morning that it went out and the lights in the shop flickered. I diagnosed it myself after coming to the shop. I ran the motor/pump and after 20 seconds it began to struggle visibly, I noticed it and right away killed the breaker. I then turned the flywheel by hand at that time and found the flywheel nearly impossible to turn as if it were seizing up. So I drained the tank, no pressure in the tank at all. Now I can turn the pump freely.

Could it just be something so simple that a couple bucks and it is fixed. That would be great :)

One reason I did not dismount it was fear of weight. I was by myself with my wife who is 90 lbs. This pump is mounted over my head in height and I am guessing the weight at maybe a couple hundred lbs. Not sure of the weight but I did not want it to crush me and my wife. It is a tall compressor and it sets on a cart making it that much taller.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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Jerry

2163 posts in 2144 days


#9 posted 352 days ago

Oh yeah, so when I removed the belt, I ran the motor free of restriction and it just hummed as nice as could be. I sniffed around the motor and everything seems in like new condition.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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dahenley

125 posts in 690 days


#10 posted 352 days ago

i read further on the eaton pump…. and found this!

This pump runs COUNTER CLOCKWISE rotation as you are looking at the compressor fan or flywheel. This pump runs at a SUPER slow RPM of 800. It can be slowed down to 600 RPMs and run with a TRUE 7.5 HP motor. Minimum RPM on this pump is 550.

guess my assumption is correct and in line with what they are saying

its going to be hard to compare the high CFM of this compressor compared to anything you will see on CL. (most CL compressors are home store compressors with less then 20 CFM MAX 0 PSI and probably in the 15CFM 100PSI and most home store compressors max out at 100/125 PSI

-- David Henley

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dahenley

125 posts in 690 days


#11 posted 352 days ago

when was the last time you changed the oil in your compressor case?
and did you use a “Non Detergent” motor oil? approx 30 weight

-- David Henley

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Jerry

2163 posts in 2144 days


#12 posted 352 days ago

I don’t know how many out there are listening. But I am thinking through this and trying to analyze the problem. If the pump seems to work just fine when little pressure is on the tank, but then struggles when pressure builds to say 140 lbs, then maybe it is something completely different than the pump itself. It would seem if the pump is broken, it would not pump even when there is no pressure in the tank. I just remember after relieving the air from the tank I found that I could turn the pump freely. I also remember when I turned the compressor on, it had about 100 lbs pressure in the tank and it ran like a champ for about 20 seconds, or until pressure built to around 140 lbs. Right now it is shut off and 0 lbs in the tank.

Maybe there is a 1 way valve that only lets air to transport from the pump to the tank and as pressure builds the pump struggles with a failed 1 way valve. Not sure….....

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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Jerry

2163 posts in 2144 days


#13 posted 352 days ago

We changed the oil approximately 30 days ago. As for it being “non detergent”. I am not sure of that but I get that stuff from Grainger and they gouge me at the tune of 10.00 per qt. It is their compressor, surely they know what to give me.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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Jerry

2163 posts in 2144 days


#14 posted 352 days ago

dahenley, what you quoted from their cite I have read. In my analyzing, I have probably read their write up 3 or so times. I am almost talking myself into going with their pump. The extra CFM will be very welcomed in our shop. We run 2 DA at one time in our shop which usually will give our 25.1 CFM we currently have a run for it’s money. Well, when we run 2 DA sanders, we might have another guy spraying or maybe another guy running a nail gun.

And in the future I dream of adding a CNC, and hopefully a wide belt sander (I think these two would use compressed air in some capacity)

I have decided not to buy any pump at this time until I have at least removed the current pump for a closer look.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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dahenley

125 posts in 690 days


#15 posted 352 days ago

there is usually a 1 way valve. and a pressure release.
when it hits peak pressure. the pump shuts off, and you will hear a hiss (releases the pressure on the compressor pump)

if a compressor is old and wore out, then sometimes when the pump is under load, it can tweak a bearing/piston/what not. (its slight, but it can happen)

look where the air line from the compressor enters the tank. thats usually where a valve will be. (mainly because air coming right off the the compressors is hot, so they usually put it further down the line for the air to cool before entering the tank.) (i know that because thats how we did on air compressors on heavy equipment.) you can melt a hose or valve off a pump if its not cooled. seen it haha

-- David Henley

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