# How long can I leave the air in compressor?



## norwei

Hi, I am a newbie. I can't find my manual for my porter cable CFNBNS kit. I bought it quite some time back and I think I threw away the manual. I can't even remember if it came with a manual but I have the break in instructions. Anyway, I finally used it today but now I don't know if I have to release the remaining air in the compressor after every use. Or can I just keep it there until next time I use it? If not, how long can I leave the air in without ruining the compressor or causing a safety issue the next time I use the air that has been left in the compressor?

I tried searching for this topic in the forum but I can't seem to find the answer. So I apologize if this question has been posted and answered before.

Thanks for your help in advance.


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## Bob Mariani

You should remove the air after using it every day. There is a relief valve at the bottom of the tank. Tilt the tank towards this valve while you open it to let the air out. This also lets all the water which is extracted from the air due to compression. Without letting the air out you leave the water in the tank. Water in the tank will rust out the tank.


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## bwalley

norwei said:


> Hi, I am a newbie. I can't find my manual for my porter cable CFNBNS kit. I bought it quite some time back and I think I threw away the manual. I can't even remember if it came with a manual but I have the break in instructions. Anyway, I finally used it today but now I don't know if I have to release the remaining air in the compressor after every use. Or can I just keep it there until next time I use it? If not, how long can I leave the air in without ruining the compressor or causing a safety issue the next time I use the air that has been left in the compressor?
> 
> I tried searching for this topic in the forum but I can't seem to find the answer. So I apologize if this question has been posted and answered before.
> 
> Thanks for your help in advance.


You are supposed to drain the compressor daily.

But I have been using compressor's for over 20 years and I rarely drain them.

The reason you are suposed to drain them daily is because you accumulate moisture in the tank and if the water stays in the tank it can cause rust and weaken the tank, possibly leading to a failure of the tank.


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## cobracdn

Well open the drain and release the water.. don't have to let all the air out  My big shop unit I drain the moisture every other day. In the winter time It's drawing cooler air from the Outside intake I'll drain it daily or if I'm using it all day (Air sanders & Tools) I'll drain it a couple times a day. Cheers


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## Scuba_Dave

One place I worked they had a sandblaster that ran all the time
It was drained on wekends
But that sucker was a heavy duty unit - not like what they make for the consumer. My friend's compressor that I use I drain every day


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## norwei

Thanks for all the reply. I appreciate it.


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## vsheetz

*unplug it...*

If storing and not using my Porter Cable pancake air compressor for some time, I open the botton valve and drain it. If I am doing a project on an ongoing basis, I don't drain it every day.

Do remember to unplug it at the end of the day - else it was kick on during the night - makes for a rude awakening!

Vince


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## clintb

I feel it should be mentioned that not only is draining the compressor tank everyday a good practice, but for those that may not follow that advice, the amount of moisture that accumulates could be heavily dependent on the relative humidity in your area. Higher humidity levels = more moisture in the air to condensate on the inner tank walls = puddle at the bottom. Use the compressor more and you have even more moisture inside.


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## n0c7

One thing I've been pondering about draining is do you leave the relief valve open or closed until next use?


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## AllanJ

Suggestion:

After turning off the compressor, leave the drain valve open so the last drops drip out except if the compressor is in a location that goes below freezing in which case close the drain valve after draining.

Otherwise the valve could be frozen in the open position when you come to use the compressor the next day.


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## johnnyboy

n0c7 said:


> One thing I've been pondering about draining is do you leave the relief valve open or closed until next use?


you're only draining it to release the condensed water so it doesn't rust the tank out and explode, 

it makes no difference whether you leave the valve open or closed, pressurized or unpressurized (although I never liked moving a charged tank, it is a bomb after all )


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## wrangler

I like to leave mine open and stay open for a minute or two after I go to use it the next time to force any remaining moisture out. Just make sure that it is in the grass or a place you don't mind rust exiting. You save very little by leaving air in the tank versus the risk of weakening the same by allowing moisture to accumulate.


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## Mr Chips

For what it's worth, I have a 33 gal craftsman that i bought about 10 years ago. I would drain it about once a month when i was using it a lot, but for the last 5 years it's seen very limited use, and hasn't been drained at all. Yesterday i noticed it has developed a leak in the bottom of the tank.

i think if i would have drained it even once every 6 months, it would still be going strong.

Anybody got a spare tank laying around they want to unload.......


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## md2lgyk

To address your other problem, try the internet. It took me all of 60 seconds to find and download the manual for a Craftsman compressor I bought at a yard sale.


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## AllanJ

When you turn it off at the end of the day, it'll have to be pumped up again the next day so you might as well drain the 100% humidity air out of it at the end of the day.

The process of compressing air wrings water vapor out and what water vapor remains in the air brings the relative humidity to 100%.

Still better is to run the compressor with the valve open for a few seconds after draining to bring new dry air (no actual compressing going on) into the tank.


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