Some air compressor questions.

[xjbmx]

Should this be in tools?

Anyway, I have a 60g 6hp DeVibliss Pro airII compressor. Now I typically try to avoid using air tools since even with a 60g tank the thing seems to never shut off when it gets any real use whitch is typically just a 90 grinder or a cut off wheel.

Yesterday I was doing alot of wire wheeling and the damn thing stayed on the whole time whitch got me thinking, why the hell I have this big *** thing taking up room when its going to run anytime I'm using it? I could just sell it for a pancake?

Anywho my question is, am I missing something? I know grinders are air hungry but sheesh! Can hose be to long? Too short? too narrow? Is my 60g really a Chinese fake and really has a 10g inside? (Yes i drain the water)

 

[lilscorpion]

High air demand tools makes even the big boys run more. I don't use air grinders and barely use cut-off wheels. I use electric grinders and always have.

Mines a huge tank but 175 psi. The high PSI rating does make a difference and allows me to unplug and run it from max to about 90 before I plug it back in. Specs of the compressor mean everything. It's possible yours can't handle the drag you put oni t unless it just runs.

To comment on the pancake comment - I have one and I assure you that you don't want one instead of your big one unless you like grinding for 2 minutes and waiting for 5.

 

[xjbmx]

Yeah, thats the reason I try to avoid air tools and usually prefer their electric counterparts. I always thought I had issues with them because I had my Dads old busted 60g Craftsman that he had ran without oil most of the time, and usually just put trans fluid in until it finally blew the motor. Now I have this and it's no different. The anoying thing is other than grinders it's only other task is filling tires. More specifically my bike tires since they need 120psi. Hmm, maybe I have to buy a second 60g tank.

 

[Heavymetalmechanic]

What is the CFM output of the compressor? At what pressure?

 

[Kaizen]

my 60gal 12.5 cfm won't keep up with a cut off wheel for more then ten minutes. I have to stop working so you're lucky if it keeps up with you. is it more about the sound that's bothering you? maybe some quieting will help

 

[Streetbu]

It;s also possible the cut off tool and grinder you're using are cheap models that use much more air than the more expensive versions. I have a 60gal compressor and it has no problems keeping up with my air tools. Even a HF blast cabinet.

 

[sberry]

Air isn't cheap, this is normal.

 

[Cyberbear]

Not all air compressors are created equal. When buying a compressor one needs to know it's capabilities relating to cfm, tank size and duty cycle. Many average a/c units are only designed to operate at a 50% duty cycle, meaning 1/2 hour on and 1/2 hour off. This doesn't mean half a day on and half a day off, because if you don't follow the manufacturer's recommendations the warranty may be voided. No one should expect a light home use a/c to perform like the commercial units, which explains the major price differences. You still only get what you pay for, and should take your larger items to a commercial sand blasting company. Always check the tool cfm usage ratings and determine before hand whether your a/c is equal to the intended job.

 

[cashishift]

Quincy or a comparable IR

another brand that people don't mention much is CastAir

 

[redmondjp]

my 60gal 12.5 cfm won't keep up with a cut off wheel for more then ten minutes. I have to stop working so you're lucky if it keeps up with you. is it more about the sound that's bothering you? maybe some quieting will help

Same here with my Rand 4000. And also agree that the air tools (esp. the imported discount ones) use far more air than is claimed on the box. The situation described by the OP is completely normal for the consumer-grade "5HP" (actual 3.3HP approx.) 60-gallon single-stage box store compressors.

I've got some 2-stage true 5HP compressors waiting in the wings (going to be keeping one of them and selling the other two - yes, I have a tool addiction problem). Then I won't have any issues with keeping up with the air die grinder or cutoff tool.

 

[sberry]

A 5 hp wil work a man continuous but keeping up with a cut wheel for 10 minutes is pretty substantial and the duty cycle may be extended with operator skill and recovery timing. Backing the pressure off a pinch helps conserve.
I painted a few cars trucks, couple semi and cement trucks with a 3 hp comp. It was 2 stage which helps some.
But how long does a guy need to cut?

 

[sberry]

I start grinding at 175, grind till air is low and break till air is back up at 160 or so and resume work and have an additional tank and can go a long time. More than any one stretch I wanna be running a tool for.

 

[sberry]

I used cut off wheels, a lot of them before we saw a plasma and a battery powered sawzall. I learned to work around that kind of thing where back in the day whizzed everything in sight. It used a lot of air and wheels and is slow and dangerous. I really stick with that as more of a problem solver than as a primary means of fabrication.

 

[sberry]

Same here with my Rand 4000. And also agree that the air tools (esp. the imported discount ones) use far more air than is claimed on the box.

Yes, 4 x and a bare minimum from the best of 3. An actual is different than a plant engineering number. In todays world it makes some sense to trade up a little bigger comp for better tools. It would be cheaper to get a 5 than upgrade a half a dozen tools.

 

[larry_g]

Should this be in tools?

Anyway, I have a 60g 6hp DeVibliss Pro airII compressor. Now I typically try to avoid using air tools since even with a 60g tank the thing seems to never shut off when it gets any real use whitch is typically just a 90 grinder or a cut off wheel.

Yesterday I was doing alot of wire wheeling and the damn thing stayed on the whole time whitch got me thinking, why the hell I have this big *** thing taking up room when its going to run anytime I'm using it? I could just sell it for a pancake?

Anywho my question is, am I missing something? I know grinders are air hungry but sheesh! Can hose be to long? Too short? too narrow? Is my 60g really a Chinese fake and really has a 10g inside? (Yes i drain the water)

Your confusing tank size with air delivery. Once the compressor turns the tank is little more than a large diameter pipe. You need to understand that the motor/compressor is what makes the pressurized air and in your situation your motor/compressor is not able to keep up with the tool your trying to run.

I'm curious what the amp draw of your motor is?

Judging a compressor by its tank size is like saying my cars gas tank is bigger so there fore I have more power.

lg
no neat sig line

 

[ronr80]

Just reading all the comment I also have an Ingersol 60g and always use air tools , what is the limit switch set at you may be too high or too low, mine only runs for 2 -3 minutes . Ron

 

[Denwood]

I had the same issue..so rather than replacing the compressor with a 220V, I just added a 2nd compressor and adjusted the pressure switch so both kick in/out at the same pressures. It's not exact but doesn't matter as when demand is high and pressure drops, both are running anyway.

 

[sberry]

Despite a common misconception the object isn't to see how much air a guy can whiz thru but to get the work done quickly. You can throttle air tools. We have done this with wire wheels, turned them down a little so wide open isn't screaming, dial it back up to the maximum power the operator needs.

 

[sberry]

The trick is to resume work just prior to shut off. In a normal cycle the pump doesn't start working till it hits kick in, you are pretty much out of air at that point.

why the hell I have this big *** thing taking up room when its going to run anytime I'm using it? I could just sell it for a pancake?

It would take 3 pancakes to do the same work.

 

[redmondjp]

The trick is to resume work just prior to shut off. In a normal cycle the pump doesn't start working till it hits kick in, you are pretty much out of air at that point.

It would take 3 pancakes to do the same work.

And they would all burn out in a couple of days as well. They are not designed for continuous duty. Forget about trying to operate any high-volume air tool with one for more than a few seconds at a time.

 

[Jere]

I can't justify running a multi horsepower compressor motor to do the same job as a 10 dollar HF plug in grinder. It is just a waste of energy that adds up slowly. The exception being hard to reach spots, or specialty air tools that don't have a corded counterpart but those are uncommon situations.

 

[xjbmx]

What is the CFM output of the compressor? At what pressure?

That I do not know, I'll have to look when I get home.

my 60gal 12.5 cfm won't keep up with a cut off wheel for more then ten minutes. I have to stop working so you're lucky if it keeps up with you. is it more about the sound that's bothering you? maybe some quieting will help

It does keep up, I can't say there is enough of a pressure drop to hinder the performance of the tool, it's just more of a question of if this is normal. Quieting would really be nice though, how would one go about that?

It;s also possible the cutoff tool and grinder you're using are cheap models that use much more air than the more expensive versions. I have a 60gal compressor and it has no problems keeping up with my air tools. Even a HF blast cabinet.

The grinder in question is a husky from HD, not sure where that sits in the quality range, probably rather low, but hopefully not in the HF rang haha. How is that blast cabinet Buy the way? I'm starting to consider one if my shop won't sell me one of our spairs.

I'm curious what the amp draw of your motor is?

Judging a compressor by its tank size is like saying my cars gas tank is bigger so there fore I have more power.

lg
no neat sig line

Not sure on that either, I'll look into it.

Just reading all the comment I also have an Ingersol 60g and always use air tools , what is the limit switch set at you may be too high or too low, mine only runs for 2 -3 minutes . Ron

The switch is set from 85psi to 120psi


Would a pressure regulator help to keep the tank from dumping it's guts as quick? It has been a long time since I've read about pressure vs flow so forgive me if it's a simple answer.

As I said, it isn't that the compressor can't keep up, but more of it seems to dump from 120 down to 85 real quick.

 

[dougf]

This is why im getting rid of my huge Husky Pro 60g. Being in the military I move a lot, and its just not practical to drag it around the country, and for what? It runs continuously when I try to do anything with it. Im getting a 30 gallon unit, selling this one, and taking any extra money and going electric, and I would recommend most people (in a casual home shop) to do the same unless the sand blast.

 

[soj]

The switch is set from 85psi to 120psi


Would a pressure regulator help to keep the tank from dumping it's guts as quick? It has been a long time since I've read about pressure vs flow so forgive me if it's a simple answer.

As I said, it isn't that the compressor can't keep up, but more of it seems to dump from 120 down to 85 real quick.

There's your problem. If you are using full tank pressure, yes, you will easily use more air that the pump can deliver. Notice that a couple of answers have suggested lowering the pressure to just what is necessary to do the work. And you can't do that without a regulator. It is a necessary part of any air system.
-jp

 

[cattoon]

As a rule i keep my shop air at 100 psi, and turn down to 80-90 when using angle grinder or inline grinder. What are you grinding that takes that length of time? I most often just use a grinder for quick clean up or to prep for welding. If I have to grind for any length of time for a mower blade or multiple blades I use an electric angle grinder, I have 3 electrics, cut off wheel, grinding disc, cupped wire brush.

 

[redmondjp]

There's your problem. If you are using full tank pressure, yes, you will easily use more air that the pump can deliver. Notice that a couple of answers have suggested lowering the pressure to just what is necessary to do the work. And you can't do that without a regulator. It is a necessary part of any air system.
-jp

I'm not sure I can agree with what you are saying - sure, the tool will use slightly more flow at a higher pressure, but it will also spin faster and deliver more power. If the pump on the compressor can't deliver the necessary CFMs that the air tool demands, it matters not what the tank size is, whether a regulator is there, how long the hose is, whether you have high-flow fittings - the compressor will simply not keep up, period.

When I am using an air die grinder or cutoff tool with my "small" compressor (same size as OP's) on a continuous basis, the pressure usually drops to 80psi or less and stays there until I let the compressor recover. The loss of power at this lower pressure is noticeable and it's much easier to stall the cutting disc.

Adding a regulator to this situation changes nothing! At most, all a regulator would do is make the reserve air in the tank last for a few more minutes of tool operation before the pressure STILL would drop to the same point and stay there.

The root-cause problem is the compressor pump is producing insufficient airflow to run the tool. There is no other way to fix that beyond delivering more air (spin pump faster or get bigger pump). I like the concept by one poster of adding a second, portable compressor to the system if needed.

With my Curtis 2-stage 5HP compressor, it simply laughs at the same air tool, shutting off for several minutes at a time during the same continuous tool use. It's all about the flow.

To the OP: to quiet yours, try remote-mounting the air inlet.

 

[xjbmx]

Cattoon
As of now (reason for the thread) I am doing alot of wire wheeling and using a Scotch Brite pad on a 90 grinder for smaller intricate spots of some of my restorations that my electric is too big to get at.

RedmondJP.

Well depleting the tank so quickly is what I would like to avoid, basically for what I am currently working on, I get maybe 2 minutes of runtime and the compressor kicks in and stays on the rest of the time. As i've said it has no problems keeping up with my grinder when it is running staying at about 80-90psi, but it cant get back up to 120psi to shut off so it keeps running if i keep grinding. So I guess I would need a larger pump to keep up.

Here is what I have, also I looked into the intake mod, thats going to be a fun one as there are two intake holes uptop at aposing sides, but I will definitely work on that, if I cant keep the thing from running constantly, I will definitely try to shut it up some.

 

[redmondjp]

Cattoon
As of now (reason for the thread) I am doing alot of wire wheeling and using a Scotch Brite pad on a 90 grinder for smaller intricate spots of some of my restorations that my electric is too big to get at.

RedmondJP.

Well depleting the tank so quickly is what I would like to avoid, basically for what I am currently working on, I get maybe 2 minutes of runtime and the compressor kicks in and stays on the rest of the time. As i've said it has no problems keeping up with my grinder when it is running staying at about 80-90psi, but it cant get back up to 120psi to shut off so it keeps running if i keep grinding. So I guess I would need a larger pump to keep up.

Here is what I have, also I looked into the intake mod, thats going to be a fun one as there are two intake holes uptop at aposing sides, but I will definitely work on that, if I cant keep the thing from running constantly, I will definitely try to shut it up some.

Thanks for posting the picture - my friend had that exact same compressor until it threw a rod recently (he got it used with the house he bought so its runtime history is unknown).

Your oilless compressors is not designed for the type of use that you are subjecting it to. It has teflon piston rings and an air-cooled crankcase (or at least most of them do) in order to cool the pistons (which the oil helps to do in a conventional wet crankcase piston compressor).

Given your situation, yes, a regulator is a great idea, set as low as you can stand for effective tool operation. But this is key - you need to let the compressor cool down between running cycles. I don't know what the design duty cycle (how much on-time vs. off-time is required so it doesn't overheat) is for your unit, but I'd say let it cool down 10-15 minutes for every 10 minutes of operation.

If you run it continuously for too long, it is not going to be a happy camper. That is pretty much the case for any consumer-duty tool (esp. small MIG welders, 5 - 10% duty cycle there).

And you are right - those large oilless units are wicked loud - not much you can do about that - with the open aluminum crankcase, there is not much metal there to dampen or absorb the sound.

If you are going to do a lot of high-volume air tool work, you might consider getting another portable compressor (20-30 gal. tank) with a conventional oil-lubricated pump on it, and paralleling it with your existing unit. That will greatly reduce the load on your existing one. Depending upon where you are at, you may be able to find a decent used one for +/- $100. Or borrow one from a friend.

 

[ms fowler]

Do you drain the water out of the tank every day?
I was in an engineering lab that used compressed air for a number of tests. They had a 30 gallon horizontal tank. I noticed it cycled about every 2 or 3 minutes, and the flow required by the test equipment was not that high. I asked when they last drained the tank, and got a blank stare. Then we drained out about 25 gallons of the dirtiest, stinkiest water I ever saw/ smelled.
Don't mean to insult, but its not uncommon to ignore the simple solutions....

 

[Streetbu]

The pic of the compressor specs tells us all what the issue is. Oiless pumps are very light duty? You don't need a bigger bigger tank necessarily, you DO need a better pump though. Probably just as easy to sell that compressor and but a better one. reasonable quality unit should be about $600 roughly and do much better for you. A larger one, (bigger tank, motor, and pump) would be even better but isn't a must.