[Malibucdl]

My Uncle is giving me a compressor. Looks to be about either a 60 or 80 gallon tank on it. It has a 230V Chichago Electric single stage motor and what I believe is a Sanborn 5HP twin cylinder pump. From what is remaining of the stickers on it, it says it is 12.7 CFm@40 PSI. Any idea what that CFM would be @90PSI?

I also think one of the bearings is going out in it, anyone know where I could get a rebuld kit for the pump?

Here are a couple pics I took with my phone while I was out there today. He should be delivering it to me sometime tomorrow.





Chris

[Danny G.]

My 60 gal single stage has some pretty close numbers. 14.55cfm@40psi, 12.85@90, 12.35@100. So I'm thinkin' you might be close to 10.5-11 cfm @ 90 psi.

[home brew]

Master tool repair has parts, all you need is a model number.

http://www.mastertoolrepair.com/stat...5_173_176.html

[oldred]

It would be far better (and probably cheaper) to just replace the pump with a Harbor Freight replacement pump. I think Danny is right on target with that 10-11 CFM@90 PSI figure but with the wear you describe the performance will be severely degraded. Simply replacing piston rings, bearings and valves is seldom satisfactory and can cost as much, or nearly so than the economy replacement pumps. As has been pointed out many times already those motor HP numbers are usually exaggerated "peak" numbers and going from the CFM numbers you have it is certainly the case here. Look at the AMP rating on the motor tag (running not start up) a real 5 HP would be at least 24 AMPS and if it says 15 AMPs then it is about 3HP, anything less than that and it will be less than 3. All this will mean nothing to you if you repair the old pump but my point is a replacement pump needs to be matched to the real power output and not the overrated "peak" numbers. I truly don't want to be discouraging here but that tank looks to be in terrible shape with what appears to be a lot of rust and if that is what we are seeing I can only imagine what the inside looks like. An exploding tank is no laughing matter and in fact many tragic accidents have been attributed to old rusty tanks, Two I have seen personally-At a mine in Ky in 1988 a 40 gal tank with about 175 PSI exploded and destroyed the cab of the Mack truck it was mounted on and another one of about the same size tank blew a hole in a garage wall big enough to drive a car through and this one had a single stage pump so I doubt if the pressure was anywhere near the one on that truck. Both these tanks had minor rusting on the outside but were rusted badly on the inside and this was determined to be the cause of the rupture, at least in the case of the one on the truck as this was investigated as a mine accident due to injuries involved. I know free may seem like a good deal but when you weigh the cost of repairs against an economy model compressor of the same or better performance and then consider what you will have with the old compressor I would have to wonder if it is worth it after taking an HONEST look at all the pros and cons of this situation. Sorry if I have been discouraging but I have been working with air systems for many years and based on what I have seen the fact is old rusty tanks just plain scare the heck out of me.

[cboy]

Originally Posted by oldred

An exploding tank is no laughing matter and in fact many tragic accidents have been attributed to old rusty tanks, Two I have seen personally-

True, an exploding tank could be a fatal event. But I wrestle in my own head with the second part of that statement. That these explosions are primarily due to rust. I don't profess any knowledge of metallurgy, so I'll just throw out the following for the sake of discussion.

I've had air tanks rust out in the past, in fact one went on me just this past year. And far from exploding, every one I've seen just starts to pathetically wheeze air out through tiny pin holes and the tank will no longer hold pressure for any length of time. From my experience rusting creates a non-uniform pattern of pits in the metal, sort of like birdshot. Lots and lots of tiny little craters of various depths. And eventually one or two of those tiny craters begins to leak air. And as it leaks air, it becomes it's own safety relief valve, bleeding off pressure from the tank and thereby preventing the sort of explosions described above. I'm open to counter theories here, but it just seems to me the natural action of rusting actually might prevent explosions rather than causing them.

[schnitz]

Actually, I'd be really worried about a relief valve failing. Mine shuts off at 130psi, any higher and the valve opens. If it doesn't work, replace it.

Just my $.02


In a while, Chet.

[oldred]

Cboy, You are right about the rust damage and fortunately this is all that happens most of the time. I have seen exactly what you describe happen many times on rusty tanks, a common occurrence around mining areas, but I have seen the two tanks I mentioned plus I have read and heard about several more so it does happen and when it does it can be devastating. There is no doubt about what caused the one on the truck as this was investigated by MSHA as a mine accident and I have no doubt about the one in the garage after examining what was left of the tank, no one was hurt that time. My point is that sometimes it just makes more sense to retire an old worn out piece of equipment because unless you spend what it will take to fix it right you will just lose what you do spend and if you spend the amount necessary then you could very well have as much in it as a new one plus there is still the safety concern of the old tank to contend with.

[oldred]

Malibu, I thought I remembered a sale item at HF recently so I looked it up and sure enough they have this.
http://www.harborfreight.com/cpi/cta...temnumber=9592

This would be a cheap easy replacement for your old pump if you decide to go that route. It probably would be cheaper than trying to repair the old one since, if as you said, it might have a bearing out and you would need to replace the crankshaft along with the bearing (probably the whole connecting rod) plus dealing with worn out cylinders. Schnitz is right about that pop-off valve it will cost very little and should be replaced, cheap insurance

[oldred]

Sorry, wrong pump

http://www.harborfreight.com/cpi/cta...emnumber=91982

This pump is on sale most of the time for $99.99

[Toyman]

I have that same Sanborn compressor. They were purchased by Coleman a few years back, so I'm not sure about the parts availability. According to my owners manual, it puts out 11.7cfm at 90 psi. (as new) Good Luck.

[Malibucdl]

Thanks alot for the information. Deffinatly opened my eyes to what I am looking at here. My uncle delivered the compressor to me lastnight and I was able to get a much better look at it. A lot of the surface rust is mainly on the front side of the tank by the stickers. The bottom of the tank has a fair amount of rust as well. The drain valve that was on bottom of the tank ( I hade to take it off to stand it up in my garage since it is not on blcoks) was full of mud, so I don't know how long it has been since the tank itself was purged. My uncle told me that there is a small pin hole in the bottom of the tank from rush, so I do know there is rust inside the tank, how bad is it, I don't know. I need to find a 1" docket so I can remove the 2 plugs that are on the tank so I can somehow look inside to see how bad it is rusted. If it is too far gone I might have to toss it out, unless I can figure out another way to restore it.

Random thought: Is it possible to cut the tank in half, repair the rust damage, then weld it back together?

Oldred: Thanks alot for the 2 links, the first pump looks like it would bolt up with out a problem, but doesn;t look to put out enough air. The second one looks like it puts out enough air, but doesn't look like it bolts on correctly. Ofcourse, I might not need either one of thoe pumps if the tank is no good.

Any suggestions on how to determine the condition of the inside of the tank, and maybe on how to repair it?

I took some pictures today and uploaded them to my photbucket account. The pictures can be seen here.

Chris

[oldred]

I knew the pump in the first link was too small and posted it by mistake, I meant to post the second one. Even similar appearing pumps usually require some modification unless they are an exact replacement and odd as it may seem the V type can most times replace the inline type fairly easily and the V type pumps seem to have better efficiency I think due to better cooling but from what you are telling us I think your biggest problem is that tank. The rust sounds really bad and if it has already rusted through, no matter how small an area, then it is clearly time to be replaced. There is no practical safe way to cut and weld a tank and this is considered a MAJOR no-no! The link below is what can happen to a rusted tank and although this tank was not ASME certified it makes little difference since the damage is due to rust and this is clearly stated. I truly wish I had a good suggestion for you but the fact is a badly rusted tank just should not be used since unfortunately they can and do explode, sometimes with devastating results.

www.doli.state.mn.us/airtank.html

[Malibucdl]

I really appreciate your input. I have yet to presurize the tank for a couple reasons: #1: I really don't want to have to put a new wall on the garage, and #2: I don't have a 230V outlet in the garage.

I am wondering if I could get a new tank and pump and build a new compressor out of what I already have, which would be the motor, regulator, and filters. Is this feasable and affordable? Or would it just be a lot easier and cheaper to buy a whole new set up?

Is there anyplace I could take the tank to get it ultrasonic tested? Maybe a dive shop?

Chris

[Toyman]

I picked up a used Speedaire 2 stage 80 gallon compressor a year or so ago. The Champion pump & 5hp GE motor work flawlessly, but the tank has seen its' better days. The only place I've found replacement tanks is Grainger. They cost more than a new compressor. I emailed Eaton, since they make/assemble their own compressors, but they don't sell the tanks by themselves. You will have to come up with $300-$400 to purchase a new unit similar to the Sanborn.

[oldred]

Toy, It just don't make sense but you are right, a replacement tank costs more than an economy compressor wih the same size tank. But did you ever price a lawn mower engine? A couple of years ago I needed a small vertical shaft gas engine and I discovered it was about 25$ dollars cheaper to buy a lawn mower with the engine I needed than it was to buy the EXACT same engine by itself It seems that the sum of the individual parts, be it compressor or what ever, is many times the cost of a complete unit but I just cannot understand how a company can justify one part costing more than all the parts as a unit.