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Compressors comparable to Viair 400p


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Way to take a part of my statement out of context.  There was a lead-in to the sentence that you quoted and it makes it correct:  With a tankless inflator, the air is compressed, goes through a regulator, and is discharged all in one process. I then went on to say:  In that case (emphasis added) it is highly unlikely (impossible I think?) to discharge the air at lower temperature than the ambient temperature that it went in at, so condensation shouldn't occur. 

What I described has nothing to do with the air conditioning or refrigerators. AC's and refrigerators work because they have condensers and evaporators that allow heat to be shed or gained in different sections of their mechanism.  

Without such devices a single pass tankless air compressor can do nothing but heat the air up as it compresses it, with some (but not complete) cooling occurring as it is discharged.  In that case it is impossible do discharge the air at a lower temperature than it entered the compressor, so no condensation.   

This is the reason that supercharged engines use an intercooler to drop the temperature of the air after compression but before entering the engine. But I haven't seen an intercooler on a tire inflator. 

I understand this just fine, thanks. 

Mark & Teri

2021 Grand Designs Imagine 2500RL, 2019 Ford F-350

Mark & Teri's Travels

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Whether it was out of context doesn't matter.  It's still wrong. When the pressure drops, the temp also drops, possibly far below ambient.  No matter whether there's a tank involved.  There's no tank in your a/c or refrigerator.  As to the part about an engine utilizing an aftercooler / intercooler/ heat exchanger, or charge air cooler, it's there because there is no pressure drop to cool the charge.

KW T-680, POPEMOBILE
Newmar X-Aire, VATICAN
Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row
Young enough to play in the dirt as a retired farmer.
contact me at rickeieio1@comcast.net

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3 hours ago, Darryl&Rita said:

Rick, that's how air conditioning and refrigeration works. The pressure drop causes a temperature drop, resulting in ahh! Cool. 

Thank you Darryl.  I learned about a/c many years ago.when I had a tractor with a cab and the a/c didn't work.

Pressure differential, combined with orifice size to control the speed of escaping gas determines temperature drop. Go to your nearest ski area and watch them make snow for a dramatic demo of dropping compressed air to below ambient, without tanks in the system.  Oh wait.  You're in southern AZ aren't you?😜

KW T-680, POPEMOBILE
Newmar X-Aire, VATICAN
Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row
Young enough to play in the dirt as a retired farmer.
contact me at rickeieio1@comcast.net

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My won ton with aftermarket rear air suspension (not add on “bags”) had a just like a Viair 400 but cheeper compressor which lasted a couple years. Now it has had a Viair 400 for over 6 years, mounted inside the frame out in the wind and mud and cold. The air intake and filter is inside the cab. 

I added a second frame mounted tank downstream from the first tank std with the system. 

The first tank has moisture in it when you drain it once in a while, the second one is dry. The system is limited to 100psi so I can only haul 5000lbs then the air spring pressure is at 100. It never tows tires higher than 80psi’sz.

rickeieio - it’s almost like that water in tank 1 falls out of the compressed air when it hits that volume of the tank vs the little braided compressor line.. 

My Viair handy dandy portable bag inflator has no tank so any moisture drop out would be inside the flat tire by my dumb logic. 

Edited by noteven

"Are we there yet?" asked no motorcycle rider, ever. 

 

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Here's how my Viair 400 is mounted in my Jeep.  It has survived tens of thousands of miles in that environment, in the heat of AZ summer, no filter, no special care given.  And I bought it used, the guy before me had it for many years too.  Every time I go off road, I air down, and then refill afterward using a T hose arrangement I made myself so I can air up all four tires at the same time, to the same pressure.

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This is the same minature water/oil filter I use on my pancake compressor in the MH.  I use another on my Harbor Freight 150#, 12V compressor, which required a bit of reworking the supply hose.  It catches more moisture from the Harbor Freight unit simply because there is no storage tank to condense water vapor prior to entering  water filter in the supply hose. https://www.ebay.com/itm/1-4-Mini-Water-Filter-Oil-Water-Separator-Filter-For-Air-Compressor-Spray-Tool-/153661825407

 

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Edited by Ray,IN

 

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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If a filter is attached to the output of a tank, it seems like it would catch more moisture since the air is already cooled, and the RH is therefore high.  Attaching it to a compressor directly seems like it would do little, because the RH of the hot air is much lower.  This is just my view of it thinking through the physics, and not something I know for sure.

 

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25 minutes ago, Carlos said:

If a filter is attached to the output of a tank, it seems like it would catch more moisture since the air is already cooled, and the RH is therefore high.  Attaching it to a compressor directly seems like it would do little, because the RH of the hot air is much lower.  This is just my view of it thinking through the physics, and not something I know for sure.

 

Your thinking is correct, until you factor in, as compressed hot air enters the tank it cools, which condenses most of humidity/ water vapor, which falls out as liquid and settles on the bottom of the tank, waiting to be drained away. The water filter catches all but a tiny bit of the rest

As someone said back a  bit, the humidity level of air entering the compressor  is simultaneously compressed, making the tank of compressed air have a corresponding higher level of humidity.

I wish I was more eloquent, but that's the best I can explain the results.

 

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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