Hello all,
Is it true that a compressor with a tank does not require a water trap? Or do all compressors require one?

Thanks,
Sean

What you mean is moisture trap right? IMO, all compressors need it. As for the one in tanks, you may or may not depending on the usage. If you use it too much in a single work, the tank will cool and lose pressure so moisture can come out.

I don't know if you need a moisture trap on a compressor with a tank or not....I have one on mine, just basically acts as a general purpose filter....not only will it stop any moisture...but also any oils in your line and compressor...as well as any dirt I would imagine. Most compressors with tanks have a relief valve on the tank itself....this is to drain any water or moisture out of the tank to prevent it from rusting out. Personally I release this valve every time when I am finished airbrushing for the night, takes a little longer to get going when you first start airbrushing, as I have to wait for the tank to fill up (about 2 mins), but better than having your tank rust out.

What really is a pain is turning the compressor on to pressurize the tank...and it goes and goes, but doesn't change the pressure reading on the tank.....then you realize that you forgot to close the water relief valve and all the air has been going out there.....just a minor goof!!

I think all compressors should have one. The trick with them is....... to put them as CLOSE to the end of the line as possible.

So the end of the line is closest to the airbrush or the compressor?

Sean

Hi Sean

As close to airbrush as possible...

I actually have two... a glass one on the compressor and a second barrel-type on the air-hose near the airbrush. Depending on the weather, I still get occasional spatters of moisture...

Quite often, moisture traps fitted to the compressor double up as air-pressure regulators.

All the best

Rowan

Hi Sean,

Yes, you need a water trap with a compressor, well actually you need one with every air source.
Why? well a compressor doesn't create air, it just gets it from the room where it stands and compresses (hence the name compressor) to the preset pressure. So if you have humid conditions in the room there will be a lot of water vapour present in your compressed air. A soon as it leaves the compressor it expands reducing its temperature, the water vapour then condenses (like steam that hits a cold surface). A water trap will aid in this proces.

The best solution is a pressure regulator/water trap solution, in this case the function of the regulator helps in condensing the water. If you work in very humid conditions it's not a bad idea to place a second in-line water trap as close to the airbrush as possible (like Rowan did).

Have fun,

Kris

Alright! That answers all my questions, thanks for the help guys!

Sean

I had been in the air compressor business for several years. The only real water traps are ones with refrigeration to drop the temperature and draw off the moisture before reheating the temperature, or ones with a dessicant to suck up the water. Any time you let compressed air expand, it cools and moisture wants to condense. So, many "water traps" are just filters. When the air expands in the chamber, moisture collects and you might think "bingo"...water gone. But, when it expands throught the next place, like your airbrush nozzle, the moisture again comes out.
Now, if the compressed air sits in the tank a while, it will cool and moisture will drop out. That's why tanks need to be drained periodically, or they'll rust.
A real air dryer would cost several hundreds of dollars or the cheaper ones probably have the same dessicant that comes in little bags to keep things dry. But, once they are saturated with water, they do not replenish themselves. There are air dryers that do. They are twin towers (sorry). When one is in line, the other is being heated to dry out the dessicant. Then they switch and again and again.
More than you ever wanted to know.

Sealhead (Kansas sunflower)

We have a couple of "air dryers" like to ones Seal mentioned at the foundry. They are huge, and expensive. I don't have a moisture trap on my compressor but I only shoot water base paint so I think I am okay. (Someone correct me if I am wrong) Whether you have a moisture trap or not, you need to drain the tank on your compressor to keep the bottom from rusting through, like Viper mentioned. A thin walled compressor is an explosion hazard. I like you guys and don't want anyone to lose a limb...

Shaun