Compressor moisture example

[AndyH]

Hi all,

It was time to change the output filter on my compressor so I was able to measure how much moisture has resulted over about ten months of use.

During this time I have topped off a 6.8 liter tank from ~170 to 300 bar eleven times. There is a dehumidifier in the basement near the compressor which should be holding the input air at 50% humidity. The white liquid in the beaker is from the accumulated output from the separator tower and is about 60ml. The weight of the output filter increased by 8 grams which I estimated to represent about 8 more ml. So a total of 68ml (~2oz) over the eleven fills. Good or bad I don’t know but it’s what I got. Hope this helps put the moisture issue in perspective. Edit: Based on initial replies I will add that each fill took about 10 minutes and I did purge the separator after each fill and left 80 bar in the compressor to keep moisture out when not in use. The point I was trying to make is if you compress this volume of 50% humidity air you will produce this amount of moisture. If you can’t account for this it is in your tank or in your gun.

 

[Eaglebeak]

I'm surprised that it's only that much if that's the first time you've drained it after all that use. The separator tower should be purged at least after every fill and more ideally during each fill as well. Maybe you now have a better understanding of what it is there for.

 

[Rodeo]

Agree with Eaglebeak. Purge every use. You might want to drain your tank, remove the valve and take a look inside.

 

[ackuric]

Just further solidifies the fact that, it doesn't matter how you compress air..moisture will always be an issue one must face...and the more steps taken to reduce and remove it, the better.



Also goes to show how shorter cycles/run times are not only beneficial for the compressor or equipment itself (keeping o-rings and other parts cool), but also greatly beneficial in the reduction of producing so much moister...

 

[AndyH]

I did purge after every fill and each fill took about 10 minutes. I saved the moisture from each fill in a water bottle until now.

 

[Rodeo]

Ok. I was scratching my head pondering that much moisture accumulated in a filter/separator. As Paul Harvey said "And now you know the rest of the story". 

 

[Yo]

Installing an a/c unit in that room will help and keep things cool and dry including you and your compressor.

 

[wyshadow]

50% humidity seems really high. I would first work on figuring out how to get that down. I would try cooling down the room with a window ac.

 

[Yo]

Good answer...SURVEY SAID!

 

[Eaglebeak]

Just further solidifies the fact that, it doesn't matter how you compress air..moisture will always be an issue one must face...and the more steps taken to reduce and remove it, the better.



Also goes to show how shorter cycles/run times are not only beneficial for the compressor or equipment itself (keeping o-rings and other parts cool), but also greatly beneficial in the reduction of producing so much moister...

Shorter run times and the temperature of the compressor have absolutely no influence on the amount of output moisture. All the compressor does is compress air at atmospheric pressure to the required high pressure. Any moisture carried as humidity on the input side will pass to the output side. None is produced. Air is compressible, water is not. Compressing air to 300 times normal atmospheric pressure (300bar) squeezes that moisture out of suspension into liquid. What goes in must come out. That is why it is far more efficient to remove the moisture on the output side when it is in liquid form than from the input side when it is gaseous. Heat is not part of the equation. I could go on about short run times causing more wear and tear than long times but that is a different subject.

 

[AndyH]

Recommended humidity levels for a comfortable home environment range from 30 to 60%. The humidity outside right now is 91%.

Check your local weather report. I think the amount of moisture in my example is probably typical and not a problem to be solved just a reality to deal with.

 

[ackuric]

Just further solidifies the fact that, it doesn't matter how you compress air..moisture will always be an issue one must face...and the more steps taken to reduce and remove it, the better.



Also goes to show how shorter cycles/run times are not only beneficial for the compressor or equipment itself (keeping o-rings and other parts cool), but also greatly beneficial in the reduction of producing so much moister...

Shorter run times and the temperature of the compressor have absolutely no influence on the amount of output moisture. All the compressor does is compress air at atmospheric pressure to the required high pressure. Any moisture carried as humidity on the input side will pass to the output side. None is produced. Air is compressible, water is not. Compressing air to 300 times normal atmospheric pressure (300bar) squeezes that moisture out of suspension into liquid. What goes in must come out. That is why it is far more efficient to remove the moisture on the output side when it is in liquid form than from the input side when it is gaseous. Heat is not part of the equation. I could go on about short run times causing more wear and tear than long times but that is a different subject.

LOL. Shorter run times and temperature of compressor have absolute influence on the amount of output moisture. Do you need a simple science lesson here in condensation? How about adiabatic heating and cooling? Do you know the formula that goes into calculating how much water will be generated based on conditions the compressor is within? You know that formula includes temperature (which run time effects)? Please enlighten me with that formula, ill wait patiently...for eternity because you will never come forth with such being it will prove you entirely wrong...

 

[ackuric]

For those that would like to both reduce wear and moisture output, keep your compressor cool when you run it, and not hot. Simple...and reduce your run time if needed to achieve this.



This applies to both oil cooled, and non-oil cooled



And to be clear, not all compressors are born equal...certainly not their ability to control moisture production...the majority of people aren't running filtration that cost more than the cheapest of compressors out there...

 

[Guest]

Andy, thank you for this post. I live in the South East and it's "Swamp a$$" season here. 50% RH inside is doing it right especially when it's 100% outside

I am very glad to see that your compressor is properly functioning and expelling water as it should. That's neat to measure the moisture output like that as the air compresses. I've never thought to do it because I was never sure what it would actually indicate -- a problem, a well designed system working properly, entropy exchange and thermodynamics, etc?

You mentioned you serviced your additional output filter (I assume an in-line filter?); how much moisture was in the additional filter? Were you able to measure the effectiveness of the output filter versus the effectiveness of the compressor moisture removal system?

Thank you!

 

[miamiguy2017]

I'm surprised that it's only that much if that's the first time you've drained it after all that use. The separator tower should be purged at least after every fill and more ideally during each fill as well. Maybe you now have a better understanding of what it is there for.

I see that you own a bauer compressor based on that blue filter. I too own a bauer junior, can you send me a couple pics of your setup? id like to see it thanks. 

 

[AndyH]

 

Hi,

The filter is inline but is part of the compressor,not an add on. I weighed the filter before and after use and it gained about 8 grams which I estimate to be about 8ml. So the separator took out 60ml and the the filter caught 8 more.

I posted this so folks could see what they are dealing with and the risk of not filtering.

 

[AndyH]

 

[Guest]

Thanks Andy! Is 8mL bad over the air volume and time period specified? I'm kind of worried now about taking my air gun outside to plink targets versus indoors. For example, if indoors I know it's 50% RH but what happens if I take it ouside to go plinking and it's 60% RH. Even worse, should I only take my air rifle outside six times even of nine?

All very careful information to consider... especially when a graduated cylinder is involved!

Thanks again for your post and all the best!

 

[Eaglebeak]

Just further solidifies the fact that, it doesn't matter how you compress air..moisture will always be an issue one must face...and the more steps taken to reduce and remove it, the better.



Also goes to show how shorter cycles/run times are not only beneficial for the compressor or equipment itself (keeping o-rings and other parts cool), but also greatly beneficial in the reduction of producing so much moister...

Shorter run times and the temperature of the compressor have absolutely no influence on the amount of output moisture. All the compressor does is compress air at atmospheric pressure to the required high pressure. Any moisture carried as humidity on the input side will pass to the output side. None is produced. Air is compressible, water is not. Compressing air to 300 times normal atmospheric pressure (300bar) squeezes that moisture out of suspension into liquid. What goes in must come out. That is why it is far more efficient to remove the moisture on the output side when it is in liquid form than from the input side when it is gaseous. Heat is not part of the equation. I could go on about short run times causing more wear and tear than long times but that is a different subject.

LOL. Shorter run times and temperature of compressor have absolute influence on the amount of output moisture. Do you need a simple science lesson here in condensation? How about adiabatic heating and cooling? Do you know the formula that goes into calculating how much water will be generated based on conditions the compressor is within? You know that formula includes temperature (which run time effects)? Please enlighten me with that formula, ill wait patiently...for eternity because you will never come forth with such being it will prove you entirely wrong...

I won't be drawn into your trap of technical BS. I will and try to explain things in layman language. You ask how much water can be generated within the compressor. My answer is none as it is already present in the atmospheric input gas in the form of vapour. It just passes from input vapour to output liquid. When that gas is compressed, the air is squeezed and the water vapour portion condenses to liquid which can't be compressed. The smaller the space that the air portion displaces, the higher percentage of liquid occupies that space. Like ringing out a sponge. My argument is that it doesn't matter how hot or cold that combination is, the amount of liquid water doesn't change. You can't turn something into nothing or turn nothing into something by heating or cooling. You may be able to change the form but the elements stay the same. Don't give me any BS about splitting atoms, it's not relevant here. "How about adiabatic heating and cooling? Do you know the formula that goes into calculating how much water will be generated based on conditions the compressor is within? You know that formula includes temperature (which run-time effects)?"This is irrelevant, It doesn't explain what you are claiming which is if you keep your compressor cool it won't make as much water. My question is, if the input humidly doesn't change, how can the output water percentage change if the only thing that is different is the operating temperature of the compressor? If so, does that mean that the missing moisture has just magically disappeared? To put things even more simply, What goes in must come out otherwise it will remain in. LOL

 

[Guest]

Eaglebeak it sounds like you're describing Charles' Law, Boyles Law, and the Law of Conservation of Energy as it relates to Entropy Exchange.

None of this will summon the legendary moisture boogeyman though. Filters must be sold and emotions must be pacified. We should be fearful of moisture for there are many a fallen air rifle subjected to the woes and sufferings of this boogeyman. And by many I mean none except for the purposely and/or excessively neglected and abused? Many espouse lack of warranty, or functionality, but yet... the evidence is sparse.