Compressor problems?

[BrokeEF]

I got a Kobalt 60 gallon 2 stage compressor a few weeks back. I finally got it all hooked up and ran the break in. Once that was done I ran it up to full pressure and I thought it seemed to take a very long time to get there. I didn't time it or anything, but it was quite a while. Anyway I needed to actually use it, so I did. I was running a needle scaler which should be ~5 to 6 SCFM at 90 psi. The compressor should shut off at 175, but I think it was 180. Regardless it should supply 7.6 SCFM at 90 psi, and after a few minutes running it would be down below 90 for sure. I think I got it as low at 60 psi even.

I am 99% sure it is wired correctly and the motor is spinning the correct direction. Nothing seems to be leaking that I know of. Not sure what else I can check. The only other thing I could think of would be to put an ammeter on it which I haven't yet. Basically I am not sure if something is wrong, or if I have too high of expectations for this compressor?

Thanks,
Sean

 

[Jswain]

First have some warm soapy water in a spray bottle ready and run compressor when it's cold so you can check the discharge tube/around the pressure switch/check valve etc. For leaks, once it shuts off continue to check & fix any leaks in your hoses/fittings etc

Then time what it takes to go from 0-175psi and report back or use an online CFM calculator to see if it's outputting what it should be.

Also you never mentioned but I'm assuming you are regulator the air pressure down to 90psi at the tool when its running?

 

[Don1357]

Is that 5~6 CFM requirement for the scaler from the vendor? That's your problem right there, they blatantly lie. Your device is more likely consuming 2~3 times that amount. The rating they advertise is the consumption you should expect if you never actually put the tool to use; the second it faces the resistance of the job at hand the air required doubles if not triples.

 

[B_Bimmer]

Most 60 gallon consumer compressors will run constantly with a needle scaler being heavily used. Generally if it keeps me going without feeling I'm lacking power I'm more than happy.

 

[atomicpunk]

A needle scaler is an air hog like an air sander.

 

[BolognaBlake]

I would expect 10-12cfm under normal use for a needle scaler.

 

[Citation]

If you search the web you can find some compressor fill/flow calculators. Based on 11cfm, 60 gal and a 175 psi cut off I would guess you need about 9 minutes to fill that tank from empty.

As for the scaler, remember that the rated flow rate is something that is used to estimate overall compressor load in a multi user environment like a factory or garage. So the mfr looks at the actual flow rate and then assumes a % of time you will actually use the tool. This is like the assumption that just because all the electrical circuits in your house adds up to over 200A doesn't mean you need more than a 200A main into your house. Anyway, based on what others say it's typically a 25-50% duty cycle. Thus you can assume the actual flow rate when you are pulling the trigger is 2-4x as much as the number quoted on the box. If it's just 2x then you are right at the limit of your pump. It can barely keep up with the tool. It sounds like it may be closer to 3-4x since it seems like you can't keep up with a continuous run. Crazy how much power (17A*230V) that needle scaler is effectively consuming.

 

[BrokeEF]

First have some warm soapy water in a spray bottle ready and run compressor when it's cold so you can check the discharge tube/around the pressure switch/check valve etc. For leaks, once it shuts off continue to check & fix any leaks in your hoses/fittings etc

Then time what it takes to go from 0-175psi and report back or use an online CFM calculator to see if it's outputting what it should be.

Also you never mentioned but I'm assuming you are regulator the air pressure down to 90psi at the tool when its running?

It doesn't have any significant leaks. It must have a small one somewhere as it drained down over a day with it all closed off (I have a shutoff valve at the discharge).

I have timed it, and it was 10 minutes 26 seconds from 0 to 175. According to the calculators I found that puts it right about 9 CFM?

Yes, it is regulated down to 90 PSI. Probably a touch lower actually.

Is that 5~6 CFM requirement for the scaler from the vendor? That's your problem right there, they blatantly lie. Your device is more likely consuming 2~3 times that amount. The rating they advertise is the consumption you should expect if you never actually put the tool to use; the second it faces the resistance of the job at hand the air required doubles if not triples.

I should have known better than to trust any specs from a manufacturer. I have been around long enough to know they are all BS!

Most 60 gallon consumer compressors will run constantly with a needle scaler being heavily used. Generally if it keeps me going without feeling I'm lacking power I'm more than happy.

This isnt a tool I normally use. I actually bought it for this specific project, and I know its a massive air hog of a tool. It did the job just fine really. I only stopped a couple times, but that wasn't so bad really. I was just doing a sanity check since according to specs (I should have known better) it uses 6.3 CFM @ 90 PSI, and the compressor does 7.6 SCFM @ 90 PSI which to me means the compressor should at worst hold at somewhere above 90 if not run and shut back down. Like I said I should have known better, and I wasn't exactly pissed or disappointed, just wanted to make sure its all working like it should.

A needle scaler is an air hog like an air sander.

I knew that going in, but I didn't quite realize how bad.

I would expect 10-12cfm under normal use for a needle scaler.

That checks out with the above calculator numbers I got.

If you search the web you can find some compressor fill/flow calculators. Based on 11cfm, 60 gal and a 175 psi cut off I would guess you need about 9 minutes to fill that tank from empty.

As for the scaler, remember that the rated flow rate is something that is used to estimate overall compressor load in a multi user environment like a factory or garage. So the mfr looks at the actual flow rate and then assumes a % of time you will actually use the tool. This is like the assumption that just because all the electrical circuits in your house adds up to over 200A doesn't mean you need more than a 200A main into your house. Anyway, based on what others say it's typically a 25-50% duty cycle. Thus you can assume the actual flow rate when you are pulling the trigger is 2-4x as much as the number quoted on the box. If it's just 2x then you are right at the limit of your pump. It can barely keep up with the tool. It sounds like it may be closer to 3-4x since it seems like you can't keep up with a continuous run. Crazy how much power (17A*230V) that needle scaler is effectively consuming.

See above where I ran the calc. I didn't really think about duty cycle, I assume balls to the wall Lesson learned (again) on just blindly following manufacturer specs.


So long story short it seems like everything is working just as it should. I may have been asking a bit much out of this thing for the scaler, but honestly it ran it pretty good I would say. If I had to run it all day every day, I wouldn't have bought this compressor in the first place. I only had a small pancake compressor, so this was a big step up. I also got this thing for really cheap so I can't really complain about it not being as good as a compressor that cost 3+ times as much.

 

[Citation]

It doesn't have any significant leaks. It must have a small one somewhere as it drained down over a day with it all closed off (I have a shutoff valve at the discharge).

I have timed it, and it was 10 minutes 26 seconds from 0 to 175. According to the calculators I found that puts it right about 9 CFM?

Yes, it is regulated down to 90 PSI. Probably a touch lower actually.



I should have known better than to trust any specs from a manufacturer. I have been around long enough to know they are all BS!



This isnt a tool I normally use. I actually bought it for this specific project, and I know its a massive air hog of a tool. It did the job just fine really. I only stopped a couple times, but that wasn't so bad really. I was just doing a sanity check since according to specs (I should have known better) it uses 6.3 CFM @ 90 PSI, and the compressor does 7.6 SCFM @ 90 PSI which to me means the compressor should at worst hold at somewhere above 90 if not run and shut back down. Like I said I should have known better, and I wasn't exactly pissed or disappointed, just wanted to make sure its all working like it should.



I knew that going in, but I didn't quite realize how bad.



That checks out with the above calculator numbers I got.



See above where I ran the calc. I didn't really think about duty cycle, I assume balls to the wall Lesson learned (again) on just blindly following manufacturer specs.


So long story short it seems like everything is working just as it should. I may have been asking a bit much out of this thing for the scaler, but honestly it ran it pretty good I would say. If I had to run it all day every day, I wouldn't have bought this compressor in the first place. I only had a small pancake compressor, so this was a big step up. I also got this thing for really cheap so I can't really complain about it not being as good as a compressor that cost 3+ times as much.

My fill calculation basically assumed you get 11cfm the whole time. I would be surprised if the compressor didn't slow down as you get towards 175 psi. You could always repeate the calculation with an assumption you would stop at say 140 psi then time the compressor from 0 to 140 psi. See if you get closer to 11 or about the same as last time.

The tool rating is probably valid but just not the way most people would think. If you are sizing a compressor for a factory it is assumed you can 100% supply a single tool but you need to think about average load. This is why I have no issue running an impact wrench even on a 4 gallon compressor. My duty cycle is low enough so the average load doesn't exceed the compressor.