[hinkley]

I didn't realize that air compression hardware has to deal with water removal but apparently it does. One article I found is suggesting that air at 7 bar can hold about 1/3 as much water. What confused me is that the a wing stall (low pressure above a wing) causes cloud formation, due to vapor condensing out of the air.

But 7 bar is ~7 times as much air per cubic centimeter, so that's 14% as much space containing 33% as much water. The partial pressure doesn't drop at a 1:1 ratio.

As a former owner of many water management devices from pet fountains to humidifiers to dehumidifiers, I'm more concerned about the fact that air is full of particulates, and you're going to wash the particulates through a fluid that stays in the pump permanently, so how quickly is the funk going to make that compressor unpleasant to be around?

[DannyBee]

Most industrial compressors (IE rotary screw, scroll, rotary vane, etc) have aftercoolers, because the temperature of compression is pretty high. The aftercooler causes most of the water to condense out.

So what you lose is efficiency, because it will take compressing more intake air to get the same yield of compressed air at a certain pressure/dewpoint.

(this is why you often see a lot of wet storage tanks for air - leaving it in the tank lets a lot of the intake air water condense at the bottom)

Aftercoolers remove a ton of of the water, and so you often get an 20 degree approach temperature.

Removing more than that requires some form of air dryer.

[breischl]

>you're going to wash the particulates through a fluid that stays in the pump permanently, so how quickly is the funk going to make that compressor unpleasant to be around?

Yeah, I was wondering about that too. But is the water going to be there permanently?

If the input air is quite dry, presumably (total guess) it would pick up some extra water. So you'd need to supply more. And probably not just tap water because of dissolved minerals and so forth - distilled seems like a better idea.

Conversely if the input air is humid, you might end up condensing water out of it, and need to bleed water from the system.

And then you're dissolving particulates in it either way...

All sounds like maintenance work, but maybe not a prohibitive amount of it.

[ska]

Looks like there is a filter on the air intake, probably partially for that latter reason (larger particulates could be a problem mechanically also).

[dusted]

When you compress air, the moisture falls out, the amount that falls out depends on pressure and temperature. pretty much all normal compressors simply have a, I don't know the right english word, but.. a valve at the bottom and once in a while (like, once a year or less, depending how much you use it) you take the pressure mostly off the compressor and open this, then the water is blown out.

[extrapickles]

Fancy air compression systems (eg: not consumer) will have a drain valve that automatically opens when the pressure falls from turning system off for night/weekend/other maintenance so people don't forget to drain it.

Its also not just water that is collected at the bottom of the air tank, compressor oil also collects. Oil can also be deliberately added by either as a byproduct of compressor design or from separate equipment, into the airstream help lubricate and protect equipment from the moisture, reducing the need to remove the moisture through other means.

[aj7]

About the only thing practical thing that valve does is perhaps lengthen the time fir the tank to rust out. Any serious industrial installation winds up with a refrigerated water removal unit.

[extrapickles]

It also helps keep a slug of water from entering the air lines if employees (and management) puts off draining the accumulated water for too long. You can also get ones that are triggered by a float if the system is for 24/7 operation.

[TheSpiceIsLife]

Any serious industrial installation will have multiple mitigation approaches.

[TheSpiceIsLife]

Ours are on a timer to blow off a small amount of air at a few low spots in the system every five minutes, even though having a refrigeratant type demudifier.

One of the devices stopped working between services and the bottom reciever tank half filled with water.

Edit: they're call bleed valves

[bluGill]

All I know is any compressed air tank you have needs water drained from it regularly. Air pipes count as a tank (just a small diameter) so you have to consider where the water will go.