Air compressor: expected life?

[Joe Frickin' Friday]

I have an air compressor that I use for sandblasting:

 

 

The air flow rate (~10 CFM) is barely adequate, and lately it seems less than it used to, particularly once the compressor has warmed up - but it's difficult to determine whether I'm imagining this or not.

 

The label brags of a 5000-hour life, but I think this is referring to the motor and its bearings, and not to the compressor and its sealing parts. Based on the amount of sandblasting work I've done so far, I'd estimate this compressor has about 100-125 hours of run time on it. I've changed the oil in the crankcase as recommended by the manual. Is this enough hours of use to compromise the piston rings? Should I be ordering a parts pack from Campbell-Hausfield?

[Danny caddyshack Noonan]

I've had mine for 20 years with little or no loss of pumping action. I did break the glaze on the cylinder a couple years ago to the detriment of it not wanting to crank unless already warm.

 

I'd be very concerned about either the piston seal or the flapper valves. If you have flappers, they can easily trap debris and get stuck and cause a loss of pressurization. You might take a look there first. I've never had that happen but one never knows.

 

If your cfm is low make sure you aren't choking the flow with too small an orifice on an adapter or fitting. Stranger things have happened.

[4wheeldog]

In my experience with air compressors (Admittedly industrial, rather than light duty) the rings are probably fine......The valves may have some deposits on them, allowing them to leak. If I were you, I would get some gaskets and take the head off. Probably any easy (And periodically needed) maintenance chore.

Good Luck!

 

ps: You are sure the air filter is not restricted, right?

[hANNAbONE]

i hAD a $250 portable C & H -- prolly didn't have 40 hours on the freekin' Home Depot purchased thang...

 

Gave up the Ghost in Sept. out of warranty of course.

 

Bought the cheapest replacement I could find.

[Shaman97]

Husky is owned by Home Depot. Don't think they have replacement parts at the store.

[kmac]

I have had my CH 6hp 60Gal AC for 16 yrs and have used the snot out of it with no issues. I would say it 1000 hrs on it at least and hard hours, Auto body long sanders are tough on AC. They burn alot of cfm and for long periods of time. I used to do some body work and she has always held up so far.

[Huzband]

Forget rebuilding it, put the 1100 RT motor on it.

 

And don't forget to post pics.

[Skywagon]

20+ years on mine works as new.

[ESokoloff]

Besides possibly wear of the valves, how do the sheaves (primarily the motor) & belt look like?

If the motor sheave is adjustable perhaps it could be adjusted in/larger dia. to increase CFM(tho that is not a compensation solution for worn component(s))

 

Also check the unloader valve & piping for leaks.

Amperage will increase with pressure.

Check RLA (Running Load Amperage) vs FLA (Full Load Amperage) just before the PE (Pressure Electric) switch opens.

If you had measured RLA when new you would have had a base line for performance.

[Joe Frickin' Friday]

If you had measured RLA when new you would have had a base line for performance.

 

Aw jeez, where were you five years ago when I bought this thing?

[CarrotNC]

Just some crazy simple questions here, and assuming the seat-of-the-pants measurement is how long it takes to clean something:

 

1) Is the tank routinely drained of condensate so capacity is preserved

2) Is the abrasive new or has it worn down

3) Is the nozzle worn down and scattering the point of aim

4) Has a feed line inside the cabinet developed a hole between gun and foot pedal

5) Did your metal supplier change sources and now it's dirtier

6) Are the air filters and dryer compenents clean and functional

7) Did a pipe fitting develop scale inside that's now broken loose and blocking flow

 

My guess would #4 as you'd really never know until it busts wide open, and those internal lines have a lot of "sanding" while feeding media to the gun.

[jrcarpenter]

If you use it mostly for sandblasting, nothing else to compare it to, you might check the nozzle for wear. If it is barely enough CFM to run the blaster, a slightly worn nozzle will make a big difference.

[kmac]

Is there any other air power tools you used the compressor with when it was new? Like an air ratchet or impact that you could use now to see if it is still similar, which may narrow down your dimished air supply to the gun or the pressure pot system.

[Calvin (no socks)]

We have a couple of commercial compressors at work....remnants of the industrial revouloution, eg. cast iron, real bearings,heavily finned. when americans made stuff...that are 60+ years old. I have an old craftsman that is 40ish...cast iron..home owner type...hobbyist...

[Joe Frickin' Friday]

1) Is the tank routinely drained of condensate so capacity is preserved

Ayup.

 

2) Is the abrasive new or has it worn down

3) Is the nozzle worn down and scattering the point of aim

4) Has a feed line inside the cabinet developed a hole between gun and foot pedal

The blaster is pretty new; I just finished it this spring, and I've probably only got a few hours of blasting time on it so far.

 

5) Did your metal supplier change sources and now it's dirtier

Nope, stock is pretty much the same as it ever was.

 

6) Are the air filters and dryer compenents clean and functional

Swapped out coalescing filter and element this summer, replaced the desiccant. All in good shape.

 

7) Did a pipe fitting develop scale inside that's now broken loose and blocking flow

Possible. About 50' of black iron pipe from compressor (in garage) to the dryer system.

 

When I use the blaster, it's for about 20 minutes at a time. When I start, the compressor's tank is full, maybe 135 psi. I get good blasting action then, but of course the tank quickly runs down, and the compressor starts; this typically happens within the first minute or two. Then it's a battle between the blasting gun and the compressor, with supply pressure decreasing until the flow through the gun has decreased enough that the compressor can keep up. But instead of quickly settling to a low-but-steady supply pressure, it seems like the equilibrium supply pressure slowly decreases over the course of my blasting session. It is as if the compressor loses CFM capacity as it warms up. So basically the first half of the blasting session goes pretty well, and the second half kind of drags on; I have to move the gun more slowly to get surfaces good and clean.

 

Maybe I just need to ugprade the compressor so that it can stay ahead of the gun?

[kmac]

But you say it worked fine when it was new? or were you just happy with it over your previous compressor? Could it be that you were happy when new, but have begun noticing its short comings over time, and that they may have been there since the begining?

[CarrotNC]

Darn it -- like you I was hoping for a cheaper & easier solution! Based on your symptoms it seems to be pointing toward the compressor unit, and if motor RPM is unchamged and the belt drive isn't slipping then that leaves just the head unit.

 

If it's worn rings then the blow-by would be fairly high, crankcase vent would be very active as the compressor warms up. So if you fit a manometer (I know you know, but for those who don't: clear vinyl tube in a U-shape filled with a bit of oil) into the oil fill plug and mark the column displacement when cold and then check it after a session of blasting to see if there's an appreciable difference. If so, then rings/bore are the likely culprit -- unless the head is cracked and then all bets are off!

 

Otherwise, the valves are the last moving part. But a broken reed would normally reduce the overall operating pressure regardless of crankcase temp.

 

Might seem expensive now, but upgrading the compressor could be cheaper in the long run in terms of time and repair bills, as well as satisfaction when using it. I finally upgraded mine this year and am stunned at the difference, really wish I'd taken that step years ago.

[Joe Frickin' Friday]

Might seem expensive now, but upgrading the compressor could be cheaper in the long run in terms of time and repair bills, as well as satisfaction when using it. I finally upgraded mine this year and am stunned at the difference, really wish I'd taken that step years ago.

 

Given how marginal it is to begin with, I've been debating whether to upgrade instead attempting to fix the existing compressor (which, as we're discussing, might not even be broken).

 

The problem is that buying a high-CFM compressor invariably means an 80-gallon tank, for which my garage does not have room. The perfect solution would be a high-CFM compressor pump attached to a 60-gallon tank, but since they don't make that, I'd have to buy a pump and attach it to my existing 60-gallon tank.

 

Candidate: NorthStar Air Compressor Pump, 22.9 CFM

 

Although it's a two-stage pump, the high CFM output still requires a lot of power - 7.5 hp, more than the existing motor can put out. That means a new big-ass motor. North Tool offers this Leeson 7.5hp motor. I've looked around at other motors on the web, and this price doesn't seem out of line.

 

Anyone have anything good or bad to say about NorthStar compressors or Leeson motors?

[g_frey]

Compressors can last over 20 years of rough use in a school setting. The loss of compression is fairly linear and the rate of loss is low (~20 to 30 PSI in 20 years). That said, the compressor/tank is probably too small for sandblasting. One fixit possibility is to make your outgoing air line a 6" or 8" schedule 40 pipe as long as can be fit into a corner of the shop. Essentially an extra air tank. These pipes can be found used at steel recyclers and need to have plate ends welded on with couplings threaded in. Proof Test: charge it up outside to max and let it sit in the sun all day. I usually plug the ends after welding (don't weld the ends completely airtight-- think about that does to the last weld! "very embarassing") and put a quart of enamel inside then roll the pipe to coat the interior, then put in the pipe fittings after drying in the sun. This helps sandblasting quite a bit depending on the final capacity. Now if your compressor was made in China, anything is possible!!!

[CarrotNC]

...The problem is that buying a high-CFM compressor invariably means an 80-gallon tank, for which my garage does not have room. The perfect solution would be a high-CFM compressor pump attached to a 60-gallon tank, but since they don't make that, I'd have to buy a pump and attach it to my existing 60-gallon tank.

 

Candidate: NorthStar Air Compressor Pump, 22.9 CFM

 

Although it's a two-stage pump, the high CFM output still requires a lot of power - 7.5 hp, more than the existing motor can put out. That means a new big-ass motor. North Tool offers this Leeson 7.5hp motor. I've looked around at other motors on the web, and this price doesn't seem out of line...

 

Thinking on the cheap here, and hoping the logic is valid, what if you kept your existing motor and put a larger pulley on the NorthStar pump you found? That'd run the head at a lower speed which your current motor should be able to handle. Heck, even if you dropped it down to 700rpm that should get you close to 14cfm at 90psi, that'd be about 30% more flow than current. And whenever the old motor finally kicks the bucket a larger one can be installed with the original pulleys.

 

Cost of a new pulley plus the pump head might be too high; perhaps a set of reduction pulleys between the motor and pump would lower the cost. One last option is to find a used 80 gallon unit and remotely mount the tank somewhere else (attic) and keep just the motor and pump in the garage. Have to build your own mounting plate but your fab skills are definitely up to a MojoMotorMount!

 

One last odd-ball option is to buy another compressor and hook them both up to the same system, perhaps trigger both motors off the same pressure switch...

[Joe Frickin' Friday]

Thinking on the cheap here, and hoping the logic is valid, what if you kept your existing motor and put a larger pulley on the NorthStar pump you found? That'd run the head at a lower speed which your current motor should be able to handle. Heck, even if you dropped it down to 700rpm that should get you close to 14cfm at 90psi, that'd be about 30% more flow than current. And whenever the old motor finally kicks the bucket a larger one can be installed with the original pulleys.

 

Sir, you are brilliant. Why didn't I think of that?

 

Your logic is indeed valid: power requirement is proportional to the product of tank pressure and flow rate. Lowering the flow rate lowers the power requirement accordingly.

 

Also, the existing pressure switch kills the motor when the tank reaches 150 psi. The Northstar compressor specs a 7.5-hp motor in order to achieve its rated 175 psi. So right off the bat, the existing pressure switch lowers the max power requirement to 6.5 hp.

 

Existing motor is rated for 4 hp, so I would only need to lower the flow rate (compressor RPM) to 60% of its rated value. That would be almost 16 CFM at 90 PSI.

 

I like it. I owe you a beer at the Un.

[ESokoloff]

Aw jeez, where were you five years ago when I bought this thing?

 

Not sure but I might have been out riding my bike at that moment but thats not important right now (in my finest Leslie Nielsen)

 

Is the Leeson motor internally protected? If not you will need a mag starter or some other type of over current protection.

[StuGotz]

Aw jeez, where were you five years ago when I bought this thing?

 

Not sure but I might have been out riding my bike at that moment but thats not important right now (in my finest Leslie Nielsen)

 

Is the Leeson motor thermally protected? If not you will need a mag starter or some other type of over current protection.

 

Fixed it for ya...

[Joe Frickin' Friday]

Aw jeez, where were you five years ago when I bought this thing?

 

Not sure but I might have been out riding my bike at that moment but thats not important right now (in my finest Leslie Nielsen)

 

Is the Leeson motor thermally protected? If not you will need a mag starter or some other type of over current protection.

 

Fixed it for ya...

 

 

I'm assuming the two big lumps are capacitors for starting, meaning no external equipment would be needed to start it. Of course I would end up confirming this before I buy it, but at this point it looks like I might not buy it at all, thanks to CarrotNC's towering, beer-worthy intellect.

[CarrotNC]

...I might not buy it at all, thanks to CarrotNC's towering, beer-worthy intellect. ...

 

Hold on there hoss! Thanks for the kind words but I can't take credit for the idea -- my compressor (Quincy QT5) uses the same pump head with different motors to achieve several distinct ratings, all based on RPM changes depending on what the motor can handle. Faster motor uses more HP but generates higher flow at pressure.

[StuGotz]

Mr. Boo

 

Check the motor nameplate for these words " thermally protected"..

 

If so, no external or additional protection is needed.

 

If not, then you MUST add this yourself, based on nameplate FLC

 

Now of course, you have to decide how to start it.

 

If manually, a HP rated switch would suffice. If automatically, then usually a mag starter is in order.

 

PM me if you need further details for your particular installation.

 

Happy compressing!

 

MB>

[kmac]

Don't be a woosy...its only money, go all out, get one of these and call it good.

 

http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6-5-125.230-3-Air-Compressor/p838.html

 

[ESokoloff]

Thinking on the cheap here, and hoping the logic is valid, what if you kept your existing motor and put a larger pulley on the NorthStar pump you found? That'd run the head at a lower speed which your current motor should be able to handle. Heck, even if you dropped it down to 700rpm that should get you close to 14cfm at 90psi, that'd be about 30% more flow than current. And whenever the old motor finally kicks the bucket a larger one can be installed with the original pulleys.

 

Sir, you are brilliant. Why didn't I think of that?

 

Your logic is indeed valid: power requirement is proportional to the product of tank pressure and flow rate. Lowering the flow rate lowers the power requirement accordingly.

 

Also, the existing pressure switch kills the motor when the tank reaches 150 psi. The Northstar compressor specs a 7.5-hp motor in order to achieve its rated 175 psi. So right off the bat, the existing pressure switch lowers the max power requirement to 6.5 hp.

 

Existing motor is rated for 4 hp, so I would only need to lower the flow rate (compressor RPM) to 60% of its rated value. That would be almost 16 CFM at 90 PSI.

 

I like it. I owe you a beer at the Un.

 

Upon re-reading all of this,

(1) Much easier to change the sheave of the motor (as apposed to the pump).

(2) Lowering the PE switch cut-out (tank pressure) will lower RLA of the motor & should allow a pump speed increase with out over amping the motor.

 

So you MIGHT be able to tweak your existing setup to achieve greater cfm output.

 

I would suggest discussing this with someone who knows their "stuff". Find a compressor sales & service shop & give them a call.

 

Here in SoCal, I use CPR Ind. (626) 444-4521

 

Many years back I was in the market for an Airless paint sprayer & was told to stay away from C-H. I would suspect & avoid any product they offer based on that.

Likely OK for light duty but not for what your asking of it.

What ever setup you end up with, put a fan nearby to help cool things off when you run it for extended periods.

 

As far as starting components needed for a replacement motor, as long as the existing PE switch is up to the task (rating) of the new motor & that motor is internally protected as is the case with the existing motor (red reset button on the end plate opposite the shaft & between the two humps) then your good to go.