Hi, you know those compressed air we can get at a gas station (to fill our tires), how "clean" are those air?

Someone told me they might have trace amount of oil (lubrication of piston).

I wonder if there are filters out there that can remove the oil so the air is clean. If so, how do such filters work and how long do they last until replacement?

I need to know this for an application I'm doing.

Thanks

 

Most of the 25 cent compressors are just cheap little buzzy piston compressors with NO storage tank. They take forever to fill a big tire and do not have the pressure range for a heavy truck tire. They usually have oil free pistons in the cheapies.

A more commercial style compressor has a storage tank and usually an oiled piston system, but some are oiless, so you have to look at the compressor to be sure.

A very tiny amount of oil may get past the piston rings and into the air supply. There are Oil capturing filters available, there are also oil Injectors. You might look into the McMaster and Carr catalogs or similar for decent oil filters etc. How long they last depends on how dirty the air is. But we have filters around our plant that have lasted several years.

Depending on how much money you want to spend you can filter most of the oil or ALL of it. Depends $$.

Usually oil is an issue with systems that might contact food products and paint sprayers and chemical processing equipment.

A bigger and more common problem is how much water is in the air? Sometimes when we start up a pipe that has been idle for a long time, it will spray out water like a garden hose, and this is even after we have a water filter at the compressor. So water is more likely to be your problem. It makes things wet, it gets funky and may be full of bacteria and it carries any contamination from inside the hose right onto what ever you are spraying. Contaminants, like crumbled rubber and OIL.

Good Luck,

Jim Henderson

 

Are you saying the compressors at gas station cannot deliver 100 psi air?

By the way, how much would a filter that virtually removes all the oil cost? For a very small air flow rate. The device is also very small, so a filter need to be small. It's really a tiny scale application but it does require clean source of compressed air.

Thanks

 

Yea,,, they can put out up to 100psi. BUT,,, got a few days to kill???

 

OT, but does anyone remember the compressed air car from France discussed here last year

I lost the link

 

Rough ballpark cost for an OIl filter is about $20-$0 for average types. For laboratory clean you can go $70 and way way up. Most commercial filters are 1/8" NPT(National Pipe Thread?) and bigger. The 1/8" In McMaster Carr fits in a closed hand and costs something like $30, but it is not laboratory grade. Most of these flow several CFM at least.

If you are into laboratory small flow applications you might look into Spectrum Chemical supply. They have all sorts of lab gear including filters. But they are VERY expensive.

Good Luck,

Jim Henderson

 

How small, unclehan? You can get compressed air in an aerosol can at a hardware store or office supply store. They use it all the time on computers and electronic gear.

 

The compressed air in those aerosol cans aren't really "air" but rather chemical gas that cannot be breathed.

The gas need to be safe to breath. That's why I initially asked if the compressed air from a gas station can work. But obviously there are traces of oil that makes it undesirable to breath directly off the bat.

I just wonder if the oil can be filtered to a low enough level so that the air willl be safe to be breathed (for 30 seconds). Do I need a lab grade filter or can a common one do just fine? I mean, the "normal" air we breath today aren't perfectly clean either.

Can the cost of filter be bought down if the quantity is large?

 

Wait, I just thought of something. How about a bicycle pump? Does that provide clean, breathable air?

But the device requires 80 psi air. I wonder if the bike pump (manual) can pump it to that much.

See, the problem that make it hard is that the air need to be breathably clean, yet easily refillable (air tank) to 80 psi by the general public.

Thanks for the help guys.

 

I think I figured out what you're after. It's for one of those 007 superspy underwater mini cigar sized shiny metallic anti-shark breathing tubes, isn't it! I knew it! I knew one day someone would mass produce those things. Kudos to you, unclehan! BTW, I'm still waiting for the jet-pak I was promised back in the fifties.

 

What kind of application are you up to? That would help us out quite a bit.

You could get a 2 gallon compressor from Home Depot, or some place like that, which would probably have an oilless compressor, or could have an oiled compressor with a filter/dryer on it. You'd be able to air up a tire no problem, but you'd be waiting a while. I used mine last week to gun some car tires off my mother in law's car, an 88 Sentra, and the compressor cycled 3 times to take two wheels off.

Maybe check into an autobody supply store, there are setups for painters wearing full suits to breathe air from a compressor. They have air filters, dryers, and regulators for the setup, and I'm sure you could adapt something out of that to store breathable compressed air in a tank.

 

If you need breathable air, go talk to a Scuba Diving shop that fills tanks.You might be able to rent a tank from them or they may be able to put 100 psi or so in a storage tank. If it does not need to be breathable look into using nitrogen.

 

I've work at a dive center and most, if not all, will not fill a tank that is not certified for scuba use. It must have a current inspection sticker and hydrostatic test. These are requirements to maintain certifications and insurance for liability. For that same reason, insurance and liability, most scuba centers will not rent a tank to someone with out a certification.

Scuba air fills are from a compressor that uses food grade oil. These compressors are made to supply breathable compressed air. They also have water and oil separators. Using air for breathing, from a non breathable air compressor, is VERY dangerous. There could be very high levels of toxins in regular compressed air.