Duty Cycle????

[JMLangford]

Will someone please explain Duty Cycle to me in layman terms (as simple as possible with no formula please....they make my head hurt)

Duty cycle as it pertains to air compressors.....I'm looking to get a larger compressor......a 60 gal vertical tank model specificity

two choices:
3.7 HP with a 50% duty cycle
5 HP with a 100% duty cycle

What does this mean in terms of operating performance in a home shop environment?.....I know bigger is better of course but at 50% duty cycle does that mean I'd be waiting on the the compressor to catch up under light to moderate use or will I be working it harder...????

If horse power (and CFM) were the same, how does the two different duty cycles affect doing the same task like using an impact (?)
Can like spec. compressors even have different duty cycles????

Will the fact that I'll be going from a 2 HP 20 gal compressor to a 60 gal tank for light to moderate use mean that duty cycle will be a moot point?

I'm sooooo corn-fused


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[sberry]

It basically needs some rest. The better one at 100 percent can run continuous.

 

[nine4gmc]

50% means if you use it for 5 mins, you better let it rest for 5 mins. 100% means you can use it non-stop.

 

[Fedwrench]

The amount of time on compared to total time.

 

[CrashmanS]

A 100% duty cycle piece of equipment will be built of higher grade and better components. This will usually come at higher price. If you only forsee yourself using a piece of equipment occasionally a lower duty cycle might suffice. I run a body shop at my house and have a 100% duty cycle 7 hp 60 gallon compressor installed to run everything I have. Could I use a 50% or less duty cycle? Yes but it wouldn't last long running on a continuous basis. That percentage is based on the number of minutes out of 10 that a machine can run at a given power output. So a 50% duty cycle compressor needs to cool down 5 minutes out of 10 or will cause damage after a while. A 100% duty cycle compressor can run continuously without much fear of overheating the motor or other items. But this always comes with proper maintainance of course.

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[L.Cheapo]

I believe duty cycle is the percentage of a 10 minute period the unit can run without needing to rest for the rest of the 10 minutes.

For instance, 50% duty cycle would run for 5 minutes (half of 10) and need to rest for the next 5.

100% duty cycle can run nonstop. 10% means it can run for 1 minute out of a 10 minute period.

 

[Strouty]

He said duty!

 

[Strouty]

I know some people think that 60% duty cycle means that if you go to work for 10 hours, you can use the compressor non-stop for 6 hours.

 

[JMLangford]

When I use my 2HP 20gal compressor.....lets say I pick up an item thats covered in sawdust and I want to clear it off.....

I have in the past just started to spray the item off and if the compressor would kick on while I was still cleaning it.......I would continued and it would eventually catch up and shut off.
Usually when that would happen I'd stop and let the compressor "rest" a bit to cool off if I wasn't finished.....

Does duty cycle have anything to do with how quick you deplete the tank to were it starts back up?



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[md21722]

For compressors it is based on an hour & for welders 10 minutes.

So a 50% duty cycle compressor you can run for 30 minutes out of 60 minutes.

Whether or not you need the duty cycle depends on how you plan on using air. Standing at a sand blast cabinet for 2 hours?

There are some reciprocating compressors that say 100% like Quincy and others like Jenny/Emglo or Champion say 80%. The inexpensive big box stores ones are probably 50%.

 

[md21722]

Duty cycle relates to the pump. How often is the pump running in a 60 minute period?

 

[CrashmanS]

When I use my 2HP 20gal compressor.....lets say I pick up an item thats covered in sawdust and I want to clear it off.....

I have in the past just started to spray the item off and if the compressor would kick on while I was still cleaning it.......I would continued and it would eventually catch up and shut off.
Usually when that would happen I'd stop and let the compressor "rest" a bit to cool off if I wasn't finished.....

Does duty cycle have anything to do with how quick you deplete the tank to were it starts back up?



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That has more to do with tank size or air reserve. But cfm is how fast the tank fills back up.


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[Strouty]

That is good to know they use an hour on compressors, I knew about the 10 minutes for welders.

 

[md21722]

There is some science behind all of it, but it mostly applies to industry where the equipment is used in production non-stop. For example, many will tell you not to start a single phase motor more than 6 times an hour, with 3 phase you can go more. They are saying this to get reasonable life out of the equipment. Single phase motors have wear parts inside related to the need for a separate starting coil.

 

[JMLangford]

Here are the two compressors:

http://www.tractorsupply.com/tsc/product/porter-cable-stationary-belt-drive-air-compressor-60-gal

http://www.tractorsupply.com/tsc/product/ingersoll-rand-5-hp-air-compressor-60-gal?cm_vc=IOPDP2

I know the IR is the superior compressor but for the $270 difference I think I can live with the 50% duty cycle in my shop! (and reduced CFM)

I was just curious about the difference in the duty cycles and what it meant and how it would mater in light to moderate use......I bet I'd never get to test the duty cycle

Thanks for all the replies!


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[Strouty]

Compressors are one of those things that I would say buy the best one you can, it will probably be around a lot longer than you think.

 

[md21722]

If you are using automotive air tools you will be far happier with a more expensive 5 HP dual stage. To get the full power out of air tools you need a compressor that cycles on around 125 PSI to account for pressure drop across hoses, couplers & swivels. The HF 5 HP dual stage is one of the few electrical tools in the store I would suggest. If you're just blowing sawdust you don't need that.

 

[JMLangford]

If you are using automotive air tools you will be far happier with a more expensive 5 HP dual stage. To get the full power out of air tools you need a compressor that cycles on around 125 PSI to account for pressure drop across hoses, couplers & swivels. The HF 5 HP dual stage is one of the few electrical tools in the store I would suggest. If you're just blowing sawdust you don't need that.

I have impacts and air ratchets which rarely see use nowdays......even if I did use them it would be sporadic......nothing like a full fledged mechanic.

My shop is mostly a woodworking shop.....I have pin, nail, and staple guns but even those see limited use and the 2 horse 20 gal compressor (and even a couple of portables) can handle them.
Spraying off items and the occasional tire fill/repair, etc.

I question whether or not I really need a bigger compressor......wtf: did I say that?)....but the PC is at an attractive price point and I thought maybe one day I might want to get one of those HF table top blast cabinets and you can never have enough air in the shop.......

Is it need or impulse?



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[CrashmanS]

That is good to know they use an hour on compressors, I knew about the 10 minutes for welders.

I learned this as well today. Mine is 100% so I guess it doesn't matter in my case.

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[Strouty]

I learned this as well today. Mine is 100% so I guess it doesn't matter in my case.

It absolutely matters, it means you can't use it for more than 60 minutes in an hour.

 

[honcho]

It absolutely matters, it means you can't use it for more than 60 minutes in an hour.

If you're a skilled flat rate mechanic and you can book more than a billable hour in an hour then do you need a compressor with a duty cycle greater than 100%?

 

[flushcut]

The PC will fit you needs just fine as long as the blast cabinet uses less air than you can supply.

 

[WWheeler]

A 100% duty cycle piece of equipment will be built of higher grade and better components. This will usually come at higher price. If you only forsee yourself using a piece of equipment occasionally a lower duty cycle might suffice. I run a body shop at my house and have a 100% duty cycle 7 hp 60 gallon compressor installed to run everything I have. Could I use a 50% or less duty cycle? Yes but it wouldn't last long running on a continuous basis. That percentage is based on the number of minutes out of 10 that a machine can run at a given power output. So a 50% duty cycle compressor needs to cool down 5 minutes out of 10 or will cause damage after a while. A 100% duty cycle compressor can run continuously without much fear of overheating the motor or other items. But this always comes with proper maintainance of course.

Exactly

I believe duty cycle is the percentage of a 10 minute period the unit can run without needing to rest for the rest of the 10 minutes.

For instance, 50% duty cycle would run for 5 minutes (half of 10) and need to rest for the next 5.

100% duty cycle can run nonstop. 10% means it can run for 1 minute out of a 10 minute period.

Yep!!

For compressors it is based on an hour & for welders 10 minutes.
So a 50% duty cycle compressor you can run for 30 minutes out of 60 minutes.


Whether or not you need the duty cycle depends on how you plan on using air. Standing at a sand blast cabinet for 2 hours?

There are some reciprocating compressors that say 100% like Quincy and others like Jenny/Emglo or Champion say 80%. The inexpensive big box stores ones are probably 50%.

No! Duty cycle for compressors is 10 minutes, not an hour. You can't let a compressor (or welder) for more than the duty cycle percentage in a 10 minute period without risking damage to the unit.

Edit: I will say that there is not an industry standard, like there should be, and that at least one company that I know of, Viair, does use a 1 hr time frame for figuring the duty cycle on their portable 12v compressors. There may be other exceptions I'm unaware of, but I've been through this with customer support at Ingersoll Rand and Porter Cable/Dewalt and their duty cycle ratings are based on 10 minute intervals.

 

[Strouty]

It does look like it is an hour, not ten minutes for a compressor.

 

[CrashmanS]

It absolutely matters, it means you can't use it for more than 60 minutes in an hour.

You just blew my mind. So as long as I don't use it more than 60 minutes in an hour the fabric of space time will remain undamaged?

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[sberry]

For 270 juice the better one is a real deal, the bigger one will also run less and 2 stage is way better. Whoops, not 2 stage. No, won't make so much difference, it's got a little better pump but only makes a little less power.

 

[American Locomotive]

It does look like it is an hour, not ten minutes for a compressor.

It's best to send an e-mail to Northern Tool or IR and ask them what time frame the duty cycle is based on.

If the compressor duty cycle is really on a 10 minute cycle - then 60% is really poor. By the time it finishes filling the tank from empty, it will probably have hit the duty cycle limit and need to rest for at least 4 minutes.

An air hogging tool like a blast cabinet will probably drain that whole tank in a lot less than 4 minutes of use.

 

[md21722]

Edit: I will say that there is not an industry standard, like there should be, and that at least one company that I know of, Viair, does use a 1 hr time frame for figuring the duty cycle on their portable 12v compressors. There may be other exceptions I'm unaware of, but I've been through this with customer support at Ingersoll Rand and Porter Cable/Dewalt and their duty cycle ratings are based on 10 minute intervals.

Thanks for the edit, you beat me to it. I was typing a response to your challenge when I saw this. I was thinking more of industrial grade compressor pumps since that's what I normally deal with.

In welding the time is an industry standard. "10 minutes is 10 minutes". It's printed in manuals. In air compressors there is no set standard. All you get is a %.

Consider that the big box store 3.x HP air compressors are 20-35 pound pumps and hold 1/2 quart of oil. They are rated 50%. Then compare to a Champion R10/R15 which is nearly 3X the weight and holds 4X more oil and its rated 80%. A 7.5/10 HP Champion R30 holds a gallon of oil.

I would say your lower end compressors rated like 5000 hours pump life mean 5 minutes on and 5 minutes off (10 minute duty cycle) whereas your higher end industrial pumps which don't even bother with pump life ratings are more like an hour duty cycle. I don't think the oil in R15's even warms up in 8 minutes.

I've also heard, though I have no direct ties to the manufacturers themselves, that the higher speed Quincy QT & IR compressors are rated 100% because they spin so fast that they get
"better" lubrication.

Quincy QT / IR T30 spin close to or more than 1000 RPM. Champion likes to spin them slower, around 730-740 RPM. The IR T30 dual stage are probably the quietest of the fast spinning dual stage I've heard.

 

[redmondjp]

I have impacts and air ratchets which rarely see use nowdays......even if I did use them it would be sporadic......nothing like a full fledged mechanic.

My shop is mostly a woodworking shop.....I have pin, nail, and staple guns but even those see limited use and the 2 horse 20 gal compressor (and even a couple of portables) can handle them.
Spraying off items and the occasional tire fill/repair, etc.

I question whether or not I really need a bigger compressor......wtf: did I say that?)....but the PC is at an attractive price point and I thought maybe one day I might want to get one of those HF table top blast cabinets and you can never have enough air in the shop.......

Is it need or impulse? .

Based upon your needs, the less-expensive compressor should serve your needs just fine (at $429 on sale, you really can't go wrong buying that unit - most used equivalent units on CrazedList are priced higher than this). And if you do need to use it for periods of heavier use, buy a $20 box fan and mount it to blow over the motor and pump.